The Human Story

Standing Upright

Some time after seven million years ago, an African ape began doing something odd: getting up off its knuckles and walking on two legs. It was not a sudden switch. Early hominins such as Sahelanthropus in Chad and Ardipithecus in Ethiopia seem to have walked upright on the ground while still climbing trees, and bipedalism was well established by around four million years ago, long before big brains or stone tools.

We know because bones and footprints record it. In 1974 Donald Johanson's team at Hadar, Ethiopia, found Lucy, a 3.2-million-year-old Australopithecus afarensis whose thigh bones angle inward to the knee, just like ours. A few years later Mary Leakey's team at Laetoli, Tanzania, uncovered a trail of footprints pressed into damp volcanic ash around 3.66 million years ago: two or more individuals walking the same way, with arched feet and big toes in line with the rest.

Standing up rebuilt the body. The skull came to balance on top of the spine, which bent into an S-curve; the pelvis shortened into a bowl; the foot traded grip for spring. Walking on two legs costs far less energy than a chimpanzee's knuckle-walk, which let hominins cover long distances across a drying, patchy landscape, and an upright body catches less of the midday sun. The hands, freed from walking, could carry food, infants and, eventually, tools. Popular stories get the order wrong, though: the oldest known stone tools, from Lomekwi in Kenya, are about 3.3 million years old, so walking came first and tool-making followed much later.

There was a bill to pay. A narrower birth canal combined with ever larger heads made human birth slow and risky, and in almost every culture mothers are helped by others when they give birth. Our backs, knees and arches carry loads they were never fully redesigned for, which is why lower-back pain, slipped discs and flat feet are so common. Every toddler retraces the journey, wobbling from crawling to walking around their first birthday.

Did you know? The Laetoli site came to light in 1976 after the palaeontologist Andrew Hill, diving to dodge a lump of dried elephant dung thrown by a colleague, noticed animal tracks fossilised in the ash.

We still live inside that ancient compromise. We walk to school and work, sit far more than our bodies expect and pay for it in sore backs, and doctors still prescribe a daily walk as medicine. Everything that followed, from carrying fire to writing books, began with an ape that stood up and kept going.

Mastering Fire

No other animal cooks. At some point our ancestors stopped fleeing wildfires and started keeping them, and the control of fire became one of the great turning points for the human body. Exactly when is fiercely debated, because a smear of charcoal can come from lightning as easily as from a hearth.

The best clues come from careful digging. In Wonderwerk Cave in South Africa, burnt bone and plant ash around one million years old lie deep inside the cave, far from any natural blaze. At Gesher Benot Ya'aqov in Israel, burnt flint and seeds clustered in patches suggest hearths about 780,000 years ago. By around 400,000 years ago, at sites such as Qesem Cave near Tel Aviv, fire use was routine, and Neanderthals later used it to make birch-bark tar, one of the first known glues. No single site settles the question; each pushes the story a little further back.

Cooking changed what a meal could do. Heat softens meat, bursts starch grains and kills many parasites, so the body extracts more energy with less chewing. The primatologist Richard Wrangham argues in Catching Fire that cooking helped shrink our teeth and guts and pay for a bigger brain, an organ that is about 2 per cent of body weight yet burns around a fifth of our resting energy. Not everyone agrees on his timing, but every human society on record cooks.

Fire reshaped the day as well as the diet. It kept leopards and hyenas at bay, warmed sleepers on cold nights and stretched waking hours after dark. When the anthropologist Polly Wiessner recorded conversations among Ju/'hoan people in Namibia and Botswana, she found that daytime talk was mostly about work, land and grumbles, while talk around the night-time fire was dominated by stories. The hearth may have been the first living room.

Did you know? The burnt remains in Wonderwerk Cave lie about 30 metres from the entrance, too deep for lightning or a bush fire to have reached them.

The flame still shapes us. Smoke from cooking fires damaged lungs in the Stone Age and still does: the World Health Organization estimates that around 2.3 billion people today cook with open fires or polluting fuels. Yet the same urge to gather round heat explains the barbecue, the campfire and the kitchen table. We are the species that tamed a wildfire and then sat down to eat beside it.

The Gift of Speech

Spoken words leave no fossils, which makes language the hardest of all human milestones to date. Most researchers think fully modern language existed by at least 100,000 years ago, and some argue that earlier humans, including Neanderthals, could speak in some form. What is certain is that it transformed what one human mind could share with another.

The evidence is indirect but telling. In 1983 a Neanderthal skeleton at Kebara Cave in Israel yielded a delicate hyoid bone, the anchor of the tongue, almost identical to ours. In the 1990s, researchers studying a London family, known as the KE family, traced a severe speech and grammar disorder to a single gene, FOXP2; ancient DNA later showed that Neanderthals carried the same version as living people. Genes and bones do not prove speech, but they show the machinery was old.

The most striking sign that language is built into us comes from Nicaragua. When new schools for deaf children opened in Managua in the late 1970s and 1980s, pupils with no shared language began inventing one in the playground and on the buses. Within a generation, younger children had given Nicaraguan Sign Language a full grammar that no teacher had taught them. Children do not just learn language; given the chance, they create it, and linguists were able to watch a new language being born.

Speech changed daily life in countless ways. It let a band plan tomorrow's hunt, warn of a snake by the river, name a cousin three valleys away and teach a child which mushrooms kill. The psychologist Robin Dunbar argues that talk, including gossip, let humans keep track of far bigger social groups than grooming ever could. Above all, words let knowledge outlive the person who first had it.

Did you know? The low larynx that lets us make so many vowel sounds also means adult humans choke on food more easily than other apes, a risk Charles Darwin himself remarked upon.

Around 7,000 languages are spoken today, from the click languages of southern Africa to the tonal languages of China and West Africa, and linguists warn that perhaps 40 per cent are endangered. Each one is a different way of carving up the world. When we chat, text or tell a bedtime story, we are using the oldest technology our species has, and still the most powerful.

Out of Africa

Every person alive today descends from people who lived in Africa. Our species, Homo sapiens, took shape there over hundreds of thousands of years: fossils from Jebel Irhoud in Morocco are around 300,000 years old, and a skull from Omo Kibish in Ethiopia is at least 230,000. Small groups ventured into the Levant, and perhaps Greece, well before 100,000 years ago, but most of those early outposts left little trace in living people.

The great dispersal that peopled the rest of the world began around 60,000 to 50,000 years ago. Genetics tells the story most clearly. In 1987 a study of mitochondrial DNA traced every living person's maternal line back to Africa, and whole genomes have since confirmed the pattern: Africa holds more human genetic diversity than any other continent, and non-Africans descend largely from one small population that crossed into Asia.

The newcomers moved fast. By around 50,000 years ago people had crossed open sea to reach Sahul, the joined landmass of Australia and New Guinea, a voyage that needed boats and planning. At Lake Mungo in New South Wales, a man buried around 42,000 years ago was laid out and sprinkled with red ochre, while a woman nearby had been cremated, one of the oldest known cremations. Teeth and bone from Bacho Kiro Cave in Bulgaria show modern humans in Europe about 45,000 years ago, and the Tianyuan man near Beijing lived around 40,000 years ago.

Each new land demanded new skills. Coastal shellfish, tropical forest, open steppe and frozen tundra required different tools, clothes and knowledge, and people adapted through culture long before their bodies changed. Over many thousands of years, populations in sunny regions kept darker skin as a shield against ultraviolet light, while lighter skin spread in some northern groups, helping the body make vitamin D in weak sunshine.

Did you know? Two people from different parts of Africa can be more genetically different from each other than a person from Norway is from a person from Japan.

Out of Africa is why humanity is one family with shallow differences. Skin colour, height and face shape vary, but beneath them every population carries the same deep African inheritance, and the old idea of sharply separate human races does not fit the genetic evidence. The map of where people live today began as a walk out of one continent.

Meeting Other Humans

For most of our history we were not alone. When modern humans left Africa, Eurasia already belonged to other kinds of people: Neanderthals from Spain to Siberia, and their eastern cousins, the Denisovans. On islands lived smaller relatives, such as Homo floresensis in Indonesia, nicknamed the hobbit. In South Africa, the small-brained Homo naledi was still alive around 250,000 years ago. For thousands of years, different humans shared the same valleys.

We know what happened when they met because their DNA is in us. In 2010 Svante Pääbo's team in Leipzig published a draft Neanderthal genome, pieced together from bones found in a Croatian cave, and showed that people outside Africa carry around 2 per cent Neanderthal DNA. Pääbo received the 2022 Nobel Prize in Physiology or Medicine for this work. Also in 2010, a tiny finger bone from Denisova Cave in Siberia revealed a whole human population known almost entirely from its genome.

Interbreeding was not a one-off. A jawbone from Peștera cu Oase in Romania, about 40,000 years old, belonged to a man who had a Neanderthal ancestor only four to six generations back. In 2018 researchers sequenced a bone fragment from a girl, nicknamed Denny, who lived in Denisova Cave around 90,000 years ago: her mother was a Neanderthal and her father a Denisovan. People in Papua New Guinea and many Aboriginal Australians carry several per cent Denisovan DNA, the highest share anywhere.

Those inherited genes still shape bodies. Many Tibetans carry a version of the EPAS1 gene, inherited from Denisovans, that helps them thrive at high altitude without their blood thickening dangerously. Neanderthal variants influence skin, hair and immunity: in 2020 Pääbo and Hugo Zeberg showed that a stretch of DNA inherited from Neanderthals raises the risk of severe COVID-19, while another Neanderthal variant appears to offer some protection.

Did you know? Even many Africans carry a little Neanderthal DNA, brought back by modern humans who returned to Africa from Eurasia thousands of years ago.

By around 40,000 years ago the Neanderthals had disappeared, and the Denisovans' trail fades too; researchers still debate why, pointing to climate swings, competition and small, scattered populations. They did not vanish completely. They live on in our cells, a reminder that the human family tree is really a tangled bush, and that Homo sapiens is the last of many ways of being human.

The First Art

At some point humans began making marks with no obvious practical use, and in doing so revealed an inner world. Some of the oldest firm evidence comes from Blombos Cave on South Africa's southern coast, where pieces of red ochre about 75,000 years old are engraved with crosshatched lines, alongside shell beads drilled for stringing. A stone flake from the same cave carries a small crosshatch drawn with an ochre crayon around 73,000 years ago.

Painting on rock appears across the world, not just in Europe. On the Indonesian island of Sulawesi, a scene of human-like figures beside a wild pig in Leang Karampuang cave has been dated to at least 51,000 years ago, using uranium-series dating of the mineral crust that formed over the paint. In the Swabian Jura of southern Germany, people carved the ivory Lion Man of Hohlenstein-Stadel and played flutes made from bird bone around 40,000 years ago.

The great painted caves of France followed. The horses, lions and rhinos of Chauvet are about 36,000 years old; those of Lascaux, found in 1940 by four teenagers exploring a hole on a hillside, are around 17,000. Hand stencils, made by blowing pigment around a hand pressed to the wall, appear from Spain to Borneo to Cueva de las Manos in Argentina, where hundreds of hands date to roughly 9,000 years ago. Studies of finger proportions suggest many stencils in Europe were made by women, though this is debated.

Why did people paint? Ideas range from hunting magic to shamans' trance visions to plain storytelling, and researchers still argue. What is clear is that art is evidence of the symbolic mind: the ability to let one thing stand for another, to picture an animal that is not there and to share that picture with others. Beads and pigments also signalled identity, telling strangers who you were and where you belonged.

Did you know? Lascaux was closed to the public in 1963 because the breath and warmth of crowds of visitors were damaging the paintings; today people tour a full-size replica nearby.

The urge has never left us. Children draw before they write, teenagers spray walls, and we decorate our bodies, homes and phones as eagerly as anyone at Chauvet. The first art was the first proof that humans live as much in imagination as in the world.

The First Friend

The dog was the first animal humans domesticated, and it happened while everyone on Earth was still a hunter-gatherer. Genetic studies agree that dogs descend from an ancient population of wolves, not from any wolf alive today, but disagree about where and when: estimates run from around 15,000 to more than 30,000 years ago, with Siberia and East Asia among the leading candidates.

How a predator became a partner is debated too. One idea is that bolder, calmer wolves scavenged around camps and gradually tamed themselves. Another, published in 2021, suggests that Ice Age hunters had more lean meat than they could safely eat in winter, since humans cannot live on protein alone, and fed the surplus to wolves. Over generations the friendliest animals bred, and domestication reshaped their skulls, coats and temperaments.

The bond shows up vividly in graves. At Bonn-Oberkassel in Germany, a man and a woman were buried around 14,000 years ago with a dog. A 2018 study found that the puppy had suffered from canine distemper and could only have survived as long as it did with weeks of nursing, care that brought no practical return. At Ain Mallaha in Israel, around 12,000 years ago, an elderly person was buried with a hand resting on a puppy. In North America, dogs were buried with care at Koster in Illinois around 10,000 years ago.

Dogs changed human life in practical ways too. They tracked and cornered game, guarded camps at night, warned of strangers and later hauled sledges across the Arctic and herded flocks. In the Arctic, the Thule people, ancestors of today's Inuit, crossed from Alaska to Greenland within the last thousand years with the help of dog-drawn sledges. When people became farmers, dogs adapted again: many breeds carry extra copies of the AMY2B gene, which helps digest starch, a genetic trace of life on the scraps of farming households.

Did you know? Dogs follow a human's pointing finger to find hidden food better than chimpanzees, our closest living relatives, usually do.

The partnership still runs both ways. In 2015 Japanese researchers found that when dogs and their owners gazed at each other, levels of oxytocin, a hormone linked to bonding, rose in both. Hundreds of millions of dogs share human lives today, guiding blind people, sniffing out drugs and disease, and keeping their owners walking. Long before we tamed wheat or cattle, we made a friend.

Surviving the Ice

Modern humans spread across the world during an ice age. At the Last Glacial Maximum, around 26,000 to 19,000 years ago, ice sheets kilometres thick covered much of northern Europe and North America, sea levels were about 120 metres lower than today, and the steppes of Eurasia were cold, dry and windy. Humans are tropical animals, so surviving there was a feat of invention rather than fur.

Clothing was the key. Bone needles with eyes appear by around 40,000 years ago in Siberia and later across Europe and China, a sign that people were sewing close-fitting, layered garments from hides and furs. Even lice tell the story: the body louse, which lives in clothing, split from the head louse at least 83,000 years ago, a hint that clothes are older still. At Sungir, near Vladimir in Russia, a man and two children buried around 34,000 years ago wore garments sewn with thousands of mammoth-ivory beads.

Shelter mattered as much. On the almost treeless plains of Ukraine, people built domed huts from mammoth bones. At Mezhyrich, around 15,000 years ago, hut walls were built from stacked jaws, skulls and leg bones, probably roofed with hides stretched over tusks and branches, with hearths inside and pits outside for storing meat in the frozen ground. Across the ice age world, people timed their moves to the migrations of reindeer, horses and bison.

Survival also depended on other people. As the ice advanced, populations in Europe shrank and retreated into milder refuges such as southern France, Iberia and Italy, then spread north again as it melted. Shells and stones carried hundreds of kilometres show that bands kept in contact, so that in a bad year a family could call on friends far away. Ancient DNA confirms that groups mixed, dwindled and replaced one another.

Did you know? Archaeologists estimate the beads on the Sungir burials took thousands of hours to make, each one carved and drilled by hand from mammoth ivory.

The same toolkit of tailored clothes, insulated shelter and long-distance friendship later carried people into the high Arctic, where the Inuit refined it into caribou-skin parkas and snow houses. Our bodies never grew a coat, and we still rely on what our ancestors learned: dress in layers, share the warmth and keep in touch. Culture, not fur, carried humans through the ice.

Reaching the Americas

The Americas were the last continents to be settled on foot. During the last ice age, so much water was locked in ice that a broad plain, Beringia, joined Siberia to Alaska. Genetic studies suggest that the ancestors of Native Americans lived in or near Beringia for several thousand years, partly cut off by ice, before moving south. Exactly when they did so is one of archaeology's liveliest debates.

For much of the twentieth century, textbooks taught Clovis first: that the makers of elegant fluted spear points, around 13,000 years ago, were the first Americans. That idea has fallen. At Monte Verde in southern Chile, Tom Dillehay's team found a camp around 14,500 years old with wooden huts, seaweed, wild potatoes and even a child's footprint. Preserved human droppings from Paisley Caves in Oregon carry human DNA over 14,000 years old. Most strikingly, footprints at White Sands in New Mexico have been dated to around 21,000 to 23,000 years ago, a date still argued over but supported by several dating methods.

How did they travel? Two routes are proposed. One followed an ice-free corridor that opened between the great ice sheets east of the Rockies. The other, increasingly favoured, ran down the Pacific coast by boat, along a "kelp highway" rich in fish, shellfish and seals. Either way, people reached the far south of South America by around 12,000 years ago, adapting along the way to tundra, prairie, rainforest and desert.

Ancient genomes have filled in the people behind the tools. The Anzick child, a boy buried in Montana with Clovis tools around 12,800 years ago, is closely related to many living Native Americans, especially in Central and South America. A teenage girl nicknamed Naia, who fell into a cave at Hoyo Negro in Mexico about 13,000 years ago, has the same Beringian ancestry. The arrival coincided with the disappearance of mammoths, giant ground sloths and American horses, though how far hunters rather than climate were to blame is debated.

Did you know? One trackway at White Sands shows a person carrying a toddler for more than a kilometre, setting the child down now and then before walking on.

Within a few thousand years the newcomers had filled two continents, and their descendants would go on to domesticate maize in Mexico and potatoes in the Andes. Today hundreds of Indigenous nations from Alaska to Patagonia trace their ancestry to that walk out of Beringia. It was the last great migration made on foot, and some of the footprints are still there.

The Cultural Animal

By the end of the last ice age, around 12,000 years ago, humans lived on every habitable continent with much the same bodies their ancestors had in Africa. What had changed was what they knew. Our real edge is cumulative culture: each generation inherits tools, skills and ideas, improves a few of them and passes the lot on. The psychologist Michael Tomasello called it a ratchet, because gains are kept rather than slipping back.

Other animals have culture, but it rarely builds up. Chimpanzees in West Africa crack nuts with stone hammers, and different groups keep different traditions, yet there is little sign their techniques have grown more complex over thousands of years. Human children are different: experiments show they copy adults faithfully, even steps that look pointless, which is exactly what you need to learn something too complicated to reinvent.

The power of inherited knowledge is clearest when it is missing. In 1861 the explorers Robert O'Hara Burke and William Wills died near Cooper Creek in Australia, in country where the Yandruwandha people lived well. The explorers ate nardoo, a fern seed the locals had shown them, but without the careful grinding and washing that made it safe, and they wasted away. Clever individuals could not out-think generations of accumulated local know-how.

Culture also depends on numbers and connections. When rising seas cut Tasmania off from mainland Australia around 10,000 years ago, its small population appears to have given up some technologies, such as bone tools, a case the anthropologist Joseph Henrich uses to argue that isolated groups can forget, though archaeologists debate how much was lost. By contrast, the Inuit of north-west Greenland, who had lost the kayak and bow, regained them in the 1860s when migrants arrived from Baffin Island led by Qitdlarssuaq.

Did you know? In experiments, young children copy unnecessary steps shown by an adult, such as tapping a box with a stick before opening it, far more faithfully than chimpanzees, who skip straight to the reward.

We are now the most culture-dependent animal that has ever lived. No one person could build a smartphone, or even a pencil, from scratch, yet billions of us use both. Schools, libraries and the internet are simply bigger ratchets. The species that walked out of Africa with stone tools ended the Ice Age with needles, boats, art, dogs and stories, and that shared inheritance, more than any single brain, set the stage for everything that followed.

The First Farmers

Around 11,500 years ago, as the last Ice Age gave way to a warmer and steadier climate, people in the hills of south-west Asia began doing something odd: putting good food back into the ground. The Neolithic Revolution was less a revolution than a slow drift, and it happened independently in at least seven places. Wheat, barley, lentils, sheep and goats in the Fertile Crescent; millet beside the Yellow River and rice along the Yangtze; taro and bananas in the New Guinea highlands; squash and maize in Mexico; potatoes and llamas in the Andes; sorghum on the southern edge of the Sahara. Nobody copied anybody. Different peoples, facing the same warming world, struck the same bargain.

The evidence is scrappy but eloquent. Archaeologists float charred seeds out of ancient hearths and measure them, and they count the bones of herds: when a site's goats are mostly young males, someone was managing them. At Kuk Swamp in Papua New Guinea, drainage ditches dug thousands of years ago still show in the soil. Ancient DNA tells the boldest story of all. Europe's first farmers were not local foragers who learned a new trick but newcomers whose ancestors came from Anatolia, reaching Greece by around 6500 BC and Britain around 4000 BC.

The skeletons also show what farming cost. In many regions early farmers were shorter than the hunter-gatherers before them. Their teeth are pitted with cavities from sticky starch, and their enamel carries faint bands where childhood hunger interrupted growth. At Abu Hureyra in Syria, the anthropologist Theya Molleson found women whose toes, knees and lower backs were deformed by hours a day kneeling at stone querns, grinding grain. Living beside animals and their dung, villagers caught diseases foragers rarely met.

Did you know? The great carved pillars of Göbekli Tepe in Turkey were raised around 9500 BC by people who, as far as excavators can tell, still lived largely by hunting and gathering wild food.

Yet farming won, because it fed more mouths from the same patch of land. Settled mothers could wean babies earlier and have a child every two or three years instead of every four, so numbers climbed. The world's population, perhaps a few million at the end of the Ice Age, reached tens of millions by around 3000 BC, though every estimate is rough. Foragers did not vanish, but they were steadily pushed to deserts, forests and the Arctic. The writer Jared Diamond famously called agriculture "the worst mistake in the history of the human race"; historians still debate how fair that verdict is.

Almost everything about modern life follows from the deal: fixed homes, calendars set by harvests, diets narrowed to a few starches, and the diseases of crowds. We are still living inside the bargain those first farmers struck: more food, more people, and far more to lose.

Taming Wild Grains

A wild wheat ear is built to fall apart. When it ripens, its rachis, the little stem that holds the grains in place, turns brittle and shatters, scattering seed for next year. For a harvester this is a nuisance: by the time you arrive with a flint sickle, much of the crop is already on the ground. A few mutant plants, though, held on to their grains. Every time people cut ripe stalks, carried them home and sowed some of the seed the following spring, they quietly favoured those mutants. Over many generations a self-sowing grass became a crop that cannot survive without us.

The evidence lies in tiny broken stalks. Under the microscope, a wild spikelet snaps off at a smooth scar, while a domestic one is torn away, and archaeobotanists count the two kinds in charred samples from site after site. In Syria and Turkey the switch to tough-stalked wheat and barley took perhaps a thousand years or more, far slower than once imagined. Genetic studies trace einkorn wheat to wild stands in the Karacadağ mountains of south-east Turkey. At Ohalo II, on the shore of the Sea of Galilee, a camp some 23,000 years old held wild barley and wheat alongside the weeds of tilled ground: the oldest known hint of people trying cultivation.

Other continents tamed other grasses. In Mexico, people of the Balsas River valley turned teosinte, a bushy plant whose few kernels sit in stone-hard cases, into maize; starch grains on grinding stones show maize there about 8,700 years ago. A handful of genes did much of the work, including one, tga1, that freed the kernel from its shell. Early cobs from Guilá Naquitz cave in Oaxaca are only a few centimetres long. In China, wild rice along the Yangtze was slowly selected for grains that stayed on the plant; at Tianluoshan, near Hangzhou, the change can be watched over the centuries around 5000 BC. In West Africa, pearl millet and African rice were tamed in the same patient way.

Did you know? Bread wheat carries six sets of chromosomes, inherited from three different wild grasses, and its genome is roughly five times the size of a human's.

The grasses changed us too. Peoples with long histories of starchy diets tend to carry extra copies of AMY1, the gene for the enzyme in saliva that begins digesting starch. Grain demanded new tools and habits: querns, ovens, storage pots, bread, porridge and beer. It also set the rhythm of the year, with every family's fortunes riding on sowing and harvest.

Today rice, wheat and maize together supply roughly half of all the calories humans eat. Each is as domestic as a dairy cow: a maize cob left in a field cannot sow itself, because its kernels never fall free. We tamed the grasses, and in return the grasses tied us to the field.

Living in Villages

For most of human history, if you disliked your neighbours you could simply walk away. Villages ended that. From around 9000 BC people in south-west Asia, and later in China, South Asia and Europe, began living year-round in the same houses, rebuilding on the same spot for generations. The most famous example is Çatalhöyük, on the Konya plain of central Turkey, occupied from about 7100 to 5950 BC by perhaps three thousand to eight thousand people at a time.

Çatalhöyük had no streets. Mud-brick houses were packed wall to wall like cells in a honeycomb, and people walked across the flat roofs, entering their homes through a hole by the smoke vent and climbing down a ladder. Inside was a single main room with an oven, a hearth, raised plastered platforms for sitting and sleeping, and storage bins for grain and lentils. Walls were replastered in white again and again, some painted with hunting scenes, and many rooms held the horns of wild bulls set into benches and pillars. James Mellaart first excavated the site in the early 1960s; Ian Hodder's team has studied it since 1993, sifting floors for seeds, hair and microscopic traces of daily life.

How do we know how villagers felt about one another? Partly from their dead. Families buried relatives beneath the floors where they slept, sometimes beneath the very platform. A study of skeletons led by Clark Spencer Larsen found that about a quarter of the skulls examined carried healed injuries, many on the back or top of the head. Crowding brought other troubles too: middens heaped against walls, mice in the grain stores, and the steady spread of infections between people and animals.

Did you know? Çatalhöyük had no front doors at street level: everyone came and went across the rooftops, which served as the town's pavements, workshops and meeting places.

Villages appeared across the world in their own forms. At Jericho, in the Jordan Valley, people built a stone tower more than eight metres high around 8000 BC, whose purpose is still argued over. At Banpo, near Xi'an in China, around 4500 BC, round and square houses clustered inside a defensive ditch, with a cemetery and pottery kilns outside. At Skara Brae on Orkney, from about 3100 BC, families furnished stone houses with stone dressers, box beds and hearths, all linked by covered passages against the wind.

Settled life invented ideas we now take for granted: the house that belongs to a family, the fence, the inheritance, the quarrel over a boundary, and the customs that keep hundreds of people from fighting every day. Every street, lease and noisy neighbour today descends from those first packed villages, where humans learned the difficult art of staying put together.

The Invention of Writing

Writing was not invented by poets. In the Sumerian city of Uruk, in what is now southern Iraq, the first tablets of around 3300 to 3200 BC are almost all accounts: sheep and goats, barley rations, beer, workers and fields. Temple administrators needed to remember who owed what to whom, and memory alone could not keep up with a city of tens of thousands. So they pressed marks into soft clay with a reed, and a new technology was born.

Its roots probably reach back further. Across the Near East, archaeologists have found thousands of small clay tokens, cones, spheres and discs, from as early as 8000 BC. The archaeologist Denise Schmandt-Besserat argued that each stood for a measure of goods, and that sealed clay envelopes called bullae, with tokens inside and their shapes impressed on the outside, led to tablets bearing the impressions alone. Not every scholar accepts the whole story, but the step from counting to writing is clear. Over centuries the pictures for "barley" or "ox" became wedge-shaped strokes, the script we call cuneiform, and signs came to stand for sounds as well as things, so that names, verbs and finally stories could be written down.

The evidence is unusually durable: baked clay survives fire, and tens of thousands of tablets fill the world's museums. One early Uruk tablet records barley over a period of 37 months and is signed "Kushim", possibly the oldest recorded name of a person, though some scholars read it as a title. A few centuries later, Enheduanna, high priestess of the moon god at Ur and daughter of King Sargon of Akkad, composed hymns around 2300 BC that survive under her name. Scribes trained for years in schools the Sumerians called "tablet houses", copying sign lists, and their practice tablets, complete with mistakes, still survive.

Did you know? Writing was invented independently at least three times: in Mesopotamia, in China, where Shang kings asked questions on oracle bones around 1250 BC, and in Mesoamerica, where scripts appear by around 600 BC.

Egypt's hieroglyphs emerged around 3200 BC, perhaps inspired by the idea from Mesopotamia, perhaps not; the ivory labels from tomb U-j at Abydos are among the oldest. Each script was a tool of a small elite. For thousands of years most people could not read, and a scribe was a powerful figure, because whoever kept the records decided what was remembered.

Writing let knowledge outlive the person who held it. Laws could be checked, debts proved, prayers repeated word for word and stories, such as the Epic of Gilgamesh, carried across a thousand years. Every receipt, contract, email and book descends from a Sumerian clerk counting barley. Writing began as bookkeeping and became the memory of the species.

The Wheel Turns

The wheel seems so obvious that it is surprising how late it came. Humans had painted caves, tamed dogs and farmed for thousands of years before anyone set a disc on an axle. Its first job was not transport at all. In Mesopotamia, from around 4500 to 3500 BC, potters began turning clay on a slow wheel, the tournette, and later on fast wheels that let one craftsman throw dozens of identical bowls a day.

Then, around 3500 to 3300 BC, wheeled vehicles appear almost at once across a huge area, from Mesopotamia to the Caucasus and central Europe. Archaeologists still debate where the idea began. A clay pot from Bronocice in Poland, dated to about 3500 BC, bears one of the oldest pictures of a four-wheeled wagon. Early Uruk tablets include a sign showing a sledge on wheels. In the marshes near Ljubljana, Slovenia, archaeologists found an actual wheel of ash planks, about 5,150 years old, with an oak axle whose square ends turned with it. Model wagons and wagon burials on the Pontic steppe show that herding peoples there used heavy carts as moving homes.

Early wheels were solid and heavy, and the wagons were pulled by oxen at walking pace. Even so, they changed lives. A cart could move harvests, manure, building stone and household goods that once travelled on human backs. The bones of cattle from this period show wear in the joints from pulling. Ancient DNA reveals that steppe herders called the Yamnaya, equipped with wagons and horses, spread far into Europe around 3000 BC and left their genetic mark on most living Europeans.

Did you know? Wheeled toys made by people in Mexico's Gulf Coast show that Mesoamericans knew the wheel, but with no horses or oxen to pull carts, they never used it for transport.

Around 2000 BC, at Sintashta in the steppes of southern Russia, people buried their dead with light chariots on wheels with spokes, fast enough for war and display. Within a few centuries chariots raced across Egypt, Anatolia, India and China; Tutankhamun was buried with several. War, prestige and long-distance trade began to move at the speed of horses. Later still, the wheel turned into machinery: the waterwheel, recorded in the Greek world by the 3rd century BC, the spinning wheel, gears, pulleys and the turbine.

Today wheels carry cars, trains and aircraft, turn every generator in a power station and spin inside watches and hard drives. One rotating idea, first used to shape a pot, still drives most of the machines that make modern life move.

Bronze and Iron

Metal began as a curiosity. Lumps of pure copper can be found lying in the ground, and people in Anatolia and North America hammered them into beads and awls thousands of years before anyone melted ore. The real breakthrough was smelting: heating green copper minerals with charcoal in a furnace until metal ran out of the rock. At Belovode in Serbia, slag shows people doing this around 5000 BC, and the art arose in several places.

Copper is soft, but mixed with about one part tin to nine parts copper it becomes bronze, hard enough to hold a keen edge and fluid enough to cast in moulds. Tin was rare, found in places such as Cornwall, Brittany and Central Asia, so bronze tied distant peoples together in long trading chains. The Uluburun shipwreck, which sank off southern Turkey around 1300 BC, carried about ten tonnes of copper ingots and around one tonne of tin, the exact proportions needed for bronze. In Shang China, foundries cast enormous ritual vessels; the Houmuwu cauldron weighs over 800 kilograms.

Metal changed bodies and societies. Ötzi, the Iceman who died in the Alps around 3300 BC, carried a copper axe, and high levels of arsenic in his hair hint that he may have worked near copper smelting. Miners at the Great Orme in Wales, around 1700 BC, dug kilometres of tunnels with bone and stone tools. Metal made weapons sharper and wealth easier to hoard. At Tollense in northern Germany, around 1250 BC, a battle along a river valley left the remains of well over a hundred people, many with arrowheads lodged in bone; it is the earliest large battlefield yet found in Europe.

Did you know? One of the daggers buried with Tutankhamun has a blade of iron that came from a meteorite, as chemical analysis published in 2016 confirmed.

Iron ore lies almost everywhere, but iron melts at a far higher temperature than copper. Smiths learned instead to heat ore in a clay bloomery furnace until a spongy lump formed, then hammer out the slag. Iron working spread through Anatolia and the Near East from around 1200 BC, and by around 500 BC smiths in West Africa, including the Nok culture of Nigeria, were smelting it too. Cheap iron sickles, axes and ploughshares reached ordinary farmers in a way costly bronze never had.

The neat labels Stone Age, Bronze Age and Iron Age were coined by the Danish curator Christian Jürgensen Thomsen in the 1830s to sort his museum's collections; real life was messier, and the ages began at different times in different places. Yet the idea holds a truth: control of materials shapes who holds power. We still name eras after what we can make, from the Steam Age to the silicon chip.

Taming the Rivers

The first great farming societies grew up beside rivers that were both generous and dangerous. Every summer the Nile rose, spread across its floodplain and drew back in autumn, leaving a layer of black silt and soaked ground ready for sowing. The Tigris and Euphrates, the Indus, and the Yellow River in China fed similar plains. Taming them meant digging channels, raising banks and storing water, and that work, done year after year, reshaped how people lived and who gave the orders.

Egyptians divided their year into three seasons set by the river: Akhet, the inundation; Peret, the season of growth when fields emerged; and Shemu, the harvest. Farmers built earth banks to trap the flood in basins, and officials measured the river's height on nilometers, stone stairways and shafts marked with a scale, because a good flood meant a good harvest and higher taxes. Too low, and people starved; too high, and villages washed away. The shaduf, a bucket on a counterweighted pole, let one person lift water to higher ground, as tomb paintings show.

In Mesopotamia the rivers flooded at the wrong time of year, just as crops ripened, so farmers dug canals and dykes to hold water back and release it later. Thousands of tablets record canal work, water rights and quarrels over both. There was a hidden cost: evaporation left salt in the soil, and records suggest farmers in the south grew more salt-tolerant barley and less wheat over time. Along the Indus, cities such as Harappa relied on the river's flood, while in China, legends of Yu the Great, who tamed floods by dredging channels rather than building walls, made water control the mark of a good ruler.

Rivers shaped bodies too. Eggs of the parasite that causes schistosomiasis, spread by snails in irrigation water, have been found in Egyptian mummies. Labour on canals and banks was often owed to the state, a duty that fell on farmers in the slack months.

Did you know? The Dujiangyan irrigation system, built in China's Sichuan province around 256 BC under the governor Li Bing, still waters the farmland of the Chengdu plain today.

In the 1950s the historian Karl Wittfogel argued that big irrigation projects created powerful, despotic states. Historians now debate this: many early systems were run by villages and temples, and the state often came first. But water certainly made planners, record keepers and tax collectors indispensable.

Irrigated land today is around a fifth of the world's farmland yet grows around two-fifths of its food, while dams and canals still decide who prospers along the Nile, the Indus and the Yellow River. The rivers made the first great farming civilisations possible, and sharing their water remains one of the oldest arguments in politics.

Written Law

Around 1754 BC, near the end of his long reign, King Hammurabi of Babylon had his laws carved on tall stone pillars and set up in public. The best preserved, a black diorite stele over two metres high, shows the king standing before Shamash, the sun god of justice. Below, in tightly packed cuneiform, run some 282 rulings, framed by a prologue declaring that the king was appointed "so that the strong might not oppress the weak". The stele was later carried off as war booty to Susa, in Iran, where French excavators found it in 1901. It now stands in the Louvre.

Hammurabi was not the first lawgiver. The code of Ur-Nammu, from the city of Ur around 2100 BC, is some three centuries older, and other Mesopotamian collections followed. But Hammurabi's is the fullest to survive, and it reads like a portrait of everyday life. It covers rented fields and flooded neighbours, unpaid debts, wages for ox drivers, fees for surgeons, faulty boats, and a builder whose badly built house collapses and kills its owner: the builder is to be put to death.

The laws were not equal. Babylonian society had three main ranks: the awīlum, a free person of standing; the muškēnum, a lower rank of free commoner; and the wardum, the enslaved. Punishment depended on who harmed whom. Knock out the eye of an awīlum and lose your own eye; harm a commoner and pay silver; harm someone else's slave and pay their owner. Women appear often: laws set out dowries and inheritance, and a wife whose husband neglected her could, in some cases, return to her father's house with her dowry. Debt slavery for a wife or child was limited to three years.

Did you know? Historians debate whether Hammurabi's laws were ever used as a working code: thousands of Babylonian court records survive, but they almost never cite the stele.

Other peoples arrived at the same idea in their own way. In Rome, around 450 BC, the Twelve Tables were displayed in the Forum after ordinary citizens demanded to know the rules being applied to them. In China in 536 BC, Zichan, chief minister of the state of Zheng, had laws cast on bronze cauldrons, to the dismay of critics who thought rulers should keep the law flexible and private. In India, the emperor Ashoka carved edicts on rocks and pillars across his realm around 260 BC.

Publishing law changed the relationship between ruler and ruled. A rule that everyone can read can be quoted back at the powerful, compared, argued over and reformed. When we expect laws to be printed, searchable and the same tomorrow as today, we are drawing on an idea carved in stone almost four thousand years ago: justice works best when the rules are visible.

The Power of Surplus

A harvest that feeds a family for a year is survival. A harvest that feeds a family and someone else is a revolution. Once farmers could reliably grow more than they ate, and store it safely, some people no longer needed to farm at all. That spare food, the surplus, quietly paid for potters, weavers, smiths, priests, scribes, soldiers and kings.

Storage came first. At Dhra', near the Dead Sea in Jordan, people built raised granaries with suspended floors around 9300 BC, before fully domestic crops existed. Later villages had bins, pits and jars sealed with clay and stamped with seals to show who had the right to open them. In Uruk, around 3300 BC, workers received their rations in mass-produced bevelled-rim bowls, crude mould-made vessels found by the hundred thousand, which many archaeologists think held standard measures of grain.

Surplus made new kinds of lives possible, and the evidence is in bones as well as buildings. At Giza, Mark Lehner and Zahi Hawass excavated the town and cemeteries of the workers who built the pyramids around 2500 BC. Their skeletons show the strain of hauling stone, with worn joints and crushed vertebrae, but also healed fractures and surgery, signs that they were fed, housed and cared for by a state that ran on grain. Bakeries and breweries turned out bread and beer by the thousands of loaves and jars. In Peru, the monumental city of Caral rose around 2600 BC on a surplus of a different kind: cotton for fishing nets, traded to coastal villages for anchovies and shellfish.

Did you know? Some of the Giza pyramid builders were buried in tombs near the pyramids with offerings of bread and beer, a sign they were respected workers rather than the slaves of popular legend.

Surplus also made inequality possible. Grain can be taxed, hoarded, stolen and inherited in a way that wild food never could. At Varna in Bulgaria, around 4500 BC, one man was buried with more gold than had been found at any earlier site in the world, while most graves held little. Studies comparing house sizes across ancient sites suggest that gaps between rich and poor widened after farming, especially in Eurasia, where ploughs and draught animals let some households farm far more land than others. Elites often grew taller than the people who fed them.

Everything that came after rests on this arrangement. In Britain today only around one worker in a hundred works on a farm, yet everyone eats, because each farmer's surplus feeds many others: teachers, nurses, coders and writers. Surplus is the hidden seed of every civilisation, and of every job that is not growing food.

The Birth of Cities

Sometime after 4000 BC, a few villages kept growing until they became something new. Uruk, in southern Mesopotamia, may have held 40,000 people or more by around 3100 BC, behind walls later credited to its legendary king Gilgamesh. Cities soon rose along the Nile at Memphis, along the Indus at Harappa and Mohenjo-daro, and in China at Erlitou. In Peru, Caral built pyramids and plazas around 2600 BC. A city was not just a big village: it was a place where most people did not farm, where strangers lived side by side, and where temples, palaces, workshops and markets packed into one dense space.

Mohenjo-daro, in today's Pakistan, flourished around 2500 BC and shows how carefully a city could be planned. On a raised citadel stood the Great Bath, a watertight brick pool sealed with bitumen. Below spread a lower town of straight streets on a rough grid, lined with houses of fired bricks made in a standard ratio of one to two to four. Many homes had a bathing area and a toilet draining into covered sewers along the street, and archaeologists estimate the city had hundreds of wells. Strangely, no grand palace or royal tomb has been found, and the Indus script remains undeciphered.

Cities transformed daily life. People bought food rather than grew it, learned trades, met speakers of other languages and could, for the first time, disappear into a crowd. Seals from the Indus have been found in Mesopotamia, evidence of merchants travelling thousands of kilometres. In Uruk, tablets list professions in order, from the chief of the city down through priests, potters and gardeners.

Did you know? For most of history, cities had more deaths than births and only kept growing by drawing in a steady stream of migrants from the countryside.

That grim fact, sometimes called the urban graveyard effect, comes from comparing burial records and later parish registers. Crowds, shared water and rubbish spread disease, and skeletons from early cities often show more signs of infection and malnutrition than those of village farmers. Cities were dangerous, yet people kept coming, drawn by work, opportunity, temples and the excitement of other people.

That pull has never stopped. Since around 2007, more than half of all humans have lived in towns and cities, and the share is still rising. The city concentrates people, and with them ideas, trade, art, disease and power, which is why so many inventions in this book began in one. Of all the things humans have built, the city is the one we have never stopped improving, and never stopped moving to.

The Gift of the Nile

Around 3100 BC the farming villages strung along the lower Nile were drawn into a single kingdom, and for roughly three thousand years, until Cleopatra's death in 30 BC, Egypt remained one of the most durable states humans have ever built. The Greek historian Herodotus called the country "the gift of the river", and he meant it literally. Each summer, monsoon rains over the Ethiopian highlands swelled the Nile, which spilled over its banks from about July to September and left behind a fresh layer of black silt. Egyptians called their land Kemet, "the black land", after that mud.

The flood set the calendar. The year had three seasons: Akhet, the inundation; Peret, when the water fell back and seed went in; and Shemu, the harvest. Officials read the river on nilometers, stone stairways marked in cubits, such as the one on Elephantine Island at Aswan, and fixed taxes by the height of the flood. A good year meant full granaries. A run of low ones, as in the troubled decades after about 2200 BC, meant hunger and political collapse.

How do we know how ordinary people lived? Largely from their bodies and their rubbish. Excavations at Giza since the late 1980s have uncovered a workers' town beside the pyramids, with bakeries, breweries and the bones of thousands of cattle, sheep and goats, and a cemetery of the builders themselves. Those tombs demolished the old myth that slaves built the pyramids: the crews were organised, rotating teams of labourers and craftsmen, fed on bread, beer and meat. Their skeletons show the price, with worn spines, crushed fingers and healed fractures, some set by physicians. Mummies reveal teeth ground down by sand and stone grit in bread, and the eggs of blood flukes caught while wading in irrigation canals.

At Deir el-Medina, the village of the craftsmen who cut the royal tombs in the Valley of the Kings, thousands of inscribed potsherds survive: shopping lists, love poems, lawsuits and work registers. Here, in about 1157 BC under Ramesses III, the workmen downed tools and sat outside the temples because their grain rations were weeks late, the first strike in recorded history.

Did you know? A Deir el-Medina register of absences records men missing work for brewing beer, being stung by a scorpion, and "embalming his brother".

Egypt's stability rested on a bargain. Farmers handed over grain and labour; the pharaoh and the priests promised maat, cosmic order, and a river that kept rising on time. The bargain outlasted every dynasty and only truly ended in 1970, when the Aswan High Dam stopped the annual flood. Today around 95 per cent of Egypt's more than 100 million people still live on the narrow green ribbon the river made, now watered by pumps and canals rather than the summer surge. The river no longer floods, but Egypt still lives exactly where the flood once reached.

Land Between Rivers

Between the Tigris and the Euphrates, in what is now southern Iraq, people tried something genuinely new around 3500 BC: living by the tens of thousands in one place. By about 2900 BC Uruk sprawled across some five square kilometres inside its walls and may have held 40,000 people or more, a scale no settlement had reached before. Its neighbours, Ur, Lagash, Kish and others, grew into rival city-states of the land the Sumerians called Kiengi.

Crowding demanded bookkeeping. Temple administrators pressed tokens and marks into clay to track barley, sheep and beer, and by about 3200 BC this had become proto-cuneiform, the earliest known writing. Most of the first tablets are accounts, not poetry, and one recurring name, Kushim, is a candidate for the first person whose name we can read. Workers were paid in barley and beer, probably measured out in crude, mass-produced bevelled-rim bowls that litter Uruk-period sites by the thousand. Writing soon found a voice of its own. Enheduanna, daughter of Sargon of Akkad and high priestess of the moon god Nanna at Ur around 2300 BC, composed hymns under her own name, which makes her the earliest named author we know.

City life had costs that bones and soils still record. Dense settlements sharing canal water bred infections, and centuries of irrigation slowly salted the fields of the south; temple records show barley, which tolerates salt, steadily replacing wheat, though historians debate how far salinisation drove political decline. Law tried to keep order among strangers. The black stone stele of Hammurabi of Babylon, set up around 1754 BC, lists 282 laws, and its famous "eye for an eye" applied mainly between equals. Injure a commoner or a slave and you paid in silver instead.

Ordinary voices survive because clay does not rot. Around 1750 BC a man named Nanni wrote to the merchant Ea-nasir in Ur, furious that he had been sold poor-quality copper and that his messenger had been treated with contempt. Babylonian astronomers, meanwhile, kept night-by-night "astronomical diaries" for centuries from about 650 BC, logging planets, eclipses, river levels and the price of barley. They counted in base 60, a system that divides neatly into halves, thirds, quarters, fifths and sixths.

Did you know? Nanni's angry tablet to Ea-nasir, now in the British Museum, is often called the oldest customer complaint in the world.

That sexagesimal habit outlived every Mesopotamian empire, including the Babylon that Cyrus of Persia took in 539 BC. Each time you book a meeting for 60 minutes, or measure a circle in 360 degrees, you are using Sumerian arithmetic. So, in a sense, is anyone who signs a contract, reads a written law or lives in a city: since around 2007 more than half of humanity has been urban. The plains between the rivers are quiet now, but we still keep their hours.

The Middle Kingdom

Around 1250 BC, at Anyang on the Yellow River plain, diviners of the Shang dynasty heated ox shoulder blades and turtle shells until they cracked, read the cracks as answers from the royal ancestors, and carved the questions alongside. Will the millet harvest be good? Will the king's toothache pass? Will the queen's childbirth go well? Around 150,000 fragments of these oracle bones have been recovered, and their script is the direct ancestor of the characters read in China today.

The bones name real people. One is Fu Hao, a consort of King Wu Ding who led armies in the field and conducted rituals in her own right. Her tomb, found intact in 1976, held hundreds of bronzes and jades, weapons among them, and the bones of sacrificed servants and dogs. Shang society rested on millet farmers whose skeletons show hard labour and frequent childhood stress, and on captives killed in their hundreds at royal funerals.

From then on, Chinese history swung between unity and division. The Zhou kings who overthrew the Shang claimed a Mandate of Heaven that could be withdrawn from bad rulers, a theory that justified both loyalty and rebellion. After centuries of war between rival states, the king of Qin unified the country in 221 BC as Qin Shi Huang, the First Emperor. His chancellor Li Si standardised the script, weights, measures, coinage and even cart axle widths, while hundreds of thousands of conscripts laboured on walls, roads and the emperor's tomb. Its guard of terracotta soldiers, perhaps 8,000 strong, each with an individual face, was found by farmers digging a well in 1974.

People lived inside this machine as entries in a register. Bamboo slips buried with a minor Qin official named Xi, found at Shuihudi in 1975, set out laws on theft, forced labour, granaries and the duties of local clerks. The Han dynasty, which followed in 206 BC and lasted four centuries, counted its subjects household by household: a census of AD 2 recorded around 57.7 million people, one of the oldest surviving population counts on Earth. The Han founded an imperial academy in 124 BC to train officials in the Confucian classics, and the scholar Ban Zhao, one of the first women historians known anywhere, completed her brother's Book of Han. Paper, credited to the court official Cai Lun in AD 105, though older fragments exist, made records cheaper still.

Did you know? Qin law punished granary officials if inspectors found three or more rat holes in their storehouse.

When the Han collapsed in AD 220, the pattern repeated: fragmentation, then reunification under the Sui and Tang. A famous novel opens with the line "The empire, long divided, must unite; long united, must divide." Yet the culture held. More than 90 per cent of China's people today call themselves Han, educated readers can still make sense of texts two thousand years old, and the idea that officials should be chosen by examination, formalised from the early 600s, echoes in civil-service tests worldwide. Dynasties fell; the paperwork, and the people it counted, carried on.

The Indus and Beyond

Around 2600 BC, along the Indus and its tributaries in today's Pakistan and north-west India, farming villages grew into planned cities. At its height the Indus or Harappan civilisation spread over an area larger than Egypt and Mesopotamia combined, and its greatest city, Mohenjo-daro, may have housed around 40,000 people. It had no obvious palaces, royal tombs or grand temples, which has made archaeologists argue for a century about who was in charge.

What it did have was plumbing. Houses were built of fired bricks in standard proportions of 1:2:4, many with a bathing platform and a toilet, and wastewater ran down chutes into covered brick drains beneath the streets, with soak pits and removable covers for cleaning. Mohenjo-daro may have had around 700 wells. The Great Bath, a watertight tank about 12 metres long sealed with bitumen, was probably used for ritual washing. Public sanitation on this scale would not appear again for many centuries.

The Indus people remain strangely quiet, because their script, found on thousands of small stamp seals, is still undeciphered; most inscriptions are only a few signs long. So their lives are read in objects and bodies. Identical cube-shaped stone weights turn up from Afghanistan to Gujarat. Mesopotamian texts mention ships from a land called Meluhha, almost certainly the Indus. In 2019 geneticists published the genome of a woman buried at Rakhigarhi: her mixed ancestry, from an Iranian-related population and South Asian hunter-gatherers, is still the largest component in most South Asians today. Skeletons from Harappa show that after about 1900 BC, as monsoons weakened and rivers shifted, injuries and diseases such as leprosy became more common, and people drifted from the cities into villages.

The subcontinent's later gifts grew from those populations. By around the 5th century BC the Buddha was teaching in the Ganges plain, and after the slaughter of the Kalinga war around 260 BC the emperor Ashoka had edicts carved on rocks and pillars urging non-violence, tolerance and medical care for people and animals. Indian mathematicians perfected decimal place value: in AD 628 Brahmagupta set out rules for calculating with zero, and an inscription at Gwalior dated AD 876 shows a round zero still recognisable today. The board game chaturanga, played by the 6th century AD, travelled west through Persia and became chess.

Did you know? Snakes and ladders began in India as moksha patam, a game in which virtues lifted players towards liberation and vices dragged them down.

Every number you write with the digits 0 to 9 descends from Indian numerals carried west by Arab scholars. Hindu, Buddhist, Jain and Sikh traditions together guide nearly two billion people. And the drains still make a point: millions of people today lack the kind of safe sanitation that Mohenjo-daro's builders gave ordinary households four and a half thousand years ago. Clean water, it turns out, is less an invention than a choice.

The Greek Experiment

Ancient Greece was never a country. It was a scatter of more than a thousand small, independent city-states, each a polis, strung from Spain to the Black Sea; Plato said the Greeks lived around their sea "like frogs around a pond". Most were small enough to walk across in a day, which meant arguments about who should decide could be tested face to face.

Athens ran the boldest test. In 508/507 BC the aristocrat Cleisthenes reorganised the citizens into ten new tribes and gave real power to an Assembly of all adult male citizens, which met on the Pnyx hill about forty times a year. A Council of 500, chosen by lot, prepared its business, and juries of hundreds, also chosen by lot and paid a daily wage from the mid-400s BC, judged cases. Stone allotment machines called kleroteria, slotted with citizens' bronze tickets and fed random black and white balls, have been found in the Agora.

We know how this worked from speeches, inscriptions, plays and broken pottery. Each year Athenians could vote to exile one prominent man for ten years by ostracism, scratching his name on a potsherd. Thousands of these ostraka survive. One cache of 190 bearing the name of the general Themistocles was written in only a handful of hands, suggesting they were prepared in advance for voters, an early hint of a political campaign.

Yet "the people" was a narrow club. Only adult men with Athenian parents could vote, perhaps 30,000 to 60,000 at different times, in a population of Attica that historians estimate at a few hundred thousand. Women, resident foreigners called metics, and tens of thousands of enslaved people, including miners worked to exhaustion in the silver galleries of Laurion, had no vote at all. Sparta, the great rival, kept a small warrior elite fed by helots, a subject people bound to the land. And democracy could be harsh: in 399 BC a jury of 501 citizens sentenced the philosopher Socrates to death for impiety and corrupting the young.

Did you know? Athenian officials swept loiterers from the Agora towards the Assembly with a rope dipped in red paint, and anyone caught with red on their clothes risked a fine.

The same small, argumentative world produced theatre, history and philosophy. At the festival of Dionysus thousands watched tragedies, and Aeschylus' The Persians, staged in 472 BC, is the oldest play that survives. Herodotus and Thucydides tried to explain events by human causes rather than divine whim, and in medicine the Hippocratic writers looked for natural causes of disease.

Athenian democracy ended under Macedonian rule in 322 BC, but the experiment never quite stopped. The word democracy, juries of ordinary people and even selection by lot survive; Ireland's Citizens' Assembly, picked at random, helped shape referendums in 2015 and 2018. Universal suffrage, though, waited until women won the vote, first nationally in New Zealand in 1893. Athens did not invent fairness; it invented the argument about who counts, and we are still having it.

The First Superpower

In about 550 BC Cyrus II, king of a modest realm in Persis in south-western Iran, began a run of conquests that within thirty years built the largest empire the world had yet seen. The Achaemenid Persian Empire stretched from Egypt and the Aegean to the Indus, and its millions of subjects spoke dozens of languages and worshipped hundreds of gods.

Persian kings chose to rule that diversity rather than erase it. When Cyrus took Babylon in 539 BC he had a clay cylinder inscribed announcing that he had restored temples and let deported peoples return home; the Hebrew Bible remembers him for allowing exiles back to Jerusalem. The Cyrus Cylinder is often called the first charter of human rights, which overstates it: it is royal propaganda in an old Mesopotamian style. But the policy was real. Provinces called satrapies, about twenty in Herodotus' count, kept their own laws, languages and priests while paying tribute and sending troops. On the stairways of the Apadana at Persepolis, carved delegations from 23 lands bring gifts: Bactrians lead a camel, Lydians carry bowls and bracelets, Indians bring baskets that probably held gold dust.

Holding it together took roads. In Herodotus' account the Royal Road ran about 2,500 kilometres from Sardis near the Aegean to Susa, with 111 staging posts. A traveller on foot needed some 90 days; relays of royal couriers, changing horses at each station, could carry a message in perhaps a week. Herodotus admired them: "neither snow nor rain nor heat nor gloom of night stays these couriers from the swift completion of their appointed rounds". The words now run across the front of a post office in New York.

The Persians also left their own words. On a cliff at Behistun, Darius I carved his account of seizing the throne in three languages, Old Persian, Elamite and Babylonian, and in the 1830s and 1840s Henry Rawlinson's copies helped scholars crack cuneiform. More intimate still are the Persepolis Fortification Tablets, tens of thousands of clay records of food rations from around 500 BC. They list workers by name, trade and sex, many of them women; record travellers drawing flour and wine on the road with sealed passes; and show the royal woman Irtashduna running her own estates and workforce.

Did you know? The Persepolis ration tablets gave new mothers extra grain and wine, with a larger bonus for a boy than for a girl.

Persian engineers spread qanats, gently sloping tunnels that bring groundwater to the surface, across dry lands from Iran to Egypt; some still flow. Alexander of Macedon conquered the empire by 330 BC, then kept much of its machinery, including its satraps, roads and royal style. Its legacy is less a monument than a method: federal provinces, local law under a single crown, and a reliable post. Persia's lasting lesson was administrative, not military: let people keep their gods, and make sure the post arrives.

The Rise of Rome

Around 750 BC, on the Palatine Hill above a marshy bend of the Tiber, shepherds and farmers lived in oval huts of wattle and daub; archaeologists have excavated the postholes. Legend says Romulus founded Rome in 753 BC. The evidence says it grew from hilltop villages that merged, drained the valley below and built a market place where the Forum would stand.

Rome's genius was less invention than absorption. After expelling its kings, traditionally in 509 BC, the Republic published its laws on the Twelve Tables around 450 BC so that ordinary citizens, the plebeians, could see the rules. It borrowed arches and augury from the Etruscans, gods and philosophy from the Greeks, and warship designs from Carthage. Defeated Italian towns became allies and, after the Social War of 91–88 BC, Roman citizens. By 146 BC, when it destroyed both Carthage and Corinth, Rome dominated the Mediterranean, and under Augustus, ruling from 27 BC, the Republic became an empire in all but name. It reached its widest extent under Trajan in AD 117.

The city swelled to perhaps a million people by Augustus' day, fed by grain shipped from Egypt and North Africa; some 200,000 citizens received a free monthly grain ration. Ancient DNA from Roman-era skeletons, published in 2019, shows that imperial Rome's people drew much of their ancestry from the eastern Mediterranean and the Near East: the capital was a migrant city. Enslaved people did much of the work, in households, workshops and the vast farming estates of the south, and in 73 BC the gladiator Spartacus led a revolt that drew tens of thousands. Skeletons from Herculaneum, killed by Vesuvius in AD 79, show hard physical labour alongside a diet rich in seafood.

Rome's subjects still speak to us. At Vindolanda, near Hadrian's Wall, ink tablets from around AD 100 include a birthday invitation from Claudia Severa to her friend Sulpicia Lepidina, with a closing greeting in Severa's own hand, the oldest known Latin handwriting by a woman. At South Shields stands the tombstone of Regina, a woman of the Catuvellauni tribe of southern Britain, once enslaved, freed and married to Barates, a man from Palmyra in Syria.

Did you know? Beneath the Latin on Regina's tombstone, Barates added a line in his own Palmyrene Aramaic: "Regina, the freedwoman of Barates, alas."

In AD 212 the emperor Caracalla extended citizenship to almost every free person in the empire, from Britain to the Euphrates, partly, historians suspect, to widen the tax base. It was nonetheless a remarkable idea: being Roman had become a legal status, not an ancestry. Rome's language lives on in the Romance tongues spoken by hundreds of millions, its months in our calendar and its law in courts across the world. Rome's real invention was not the arch but the citizen who did not need to be born Roman.

Roads, Law, Aqueducts

In 312 BC the Roman censor Appius Claudius Caecus began two projects that would define his city: the Via Appia, a paved highway south towards Capua, and the Aqua Appia, Rome's first aqueduct. Over the next five centuries Rome laid some 80,000 kilometres of paved main roads, from Hadrian's Wall to the Euphrates. Engineering manuals describe them in layers: large foundation stones, a bed of rubble, a core of gravel and lime, and fitted paving cambered to shed rain, though real roads varied with terrain and budget. Milestones counted the distance, and soldiers, merchants, letters and diseases travelled them at walking pace, some 30 kilometres a day.

Water was the empire's other obsession. By the 3rd century AD eleven aqueducts supplied Rome, feeding public fountains, baths and latrines. The water commissioner Frontinus, appointed in AD 97, wrote a treatise on them and complained bitterly about illegal taps. In southern France the Pont du Gard carries the aqueduct of Nîmes across the river Gardon on three tiers of arches about 49 metres high, part of a channel some 50 kilometres long that drops only around 12 metres from source to city.

Much of this rested on Roman concrete, opus caementicium, made with lime and volcanic ash called pozzolana, which could set even under seawater. The harbour of Caesarea in Judaea was poured into the sea, and the dome of the Pantheon, finished around AD 125, is still the largest unreinforced concrete dome in the world. A 2023 study found that small lumps of lime in the mix let cracks heal themselves when water seeped in.

Did all this make people healthier? Less than you might think. A study of Roman-era latrines, sewers and burials by the archaeologist Piers Mitchell found that roundworm, whipworm and dysentery-causing parasites were no rarer than before Rome, while fish tapeworm spread, perhaps with garum, the popular fermented fish sauce. Warm, rarely changed bathwater may have helped infections along. The popular claim that lead pipes poisoned Rome into decline is exaggerated: hard water coated many pipes with mineral scale.

Did you know? The Trevi Fountain in Rome is still fed by the Aqua Virgo, an aqueduct first opened in 19 BC.

The most portable Roman structure was law. From the Twelve Tables through generations of jurists such as Ulpian, Roman law built up rules on contracts, property, inheritance and evidence. Between 529 and 534 the eastern emperor Justinian had it compiled into the Corpus Juris Civilis. Rediscovered in Bologna in the late 11th century, it became the basis of the civil law systems that govern most of continental Europe, Latin America, Quebec and Louisiana, and shaped codes from Japan to Turkey. Its principle that the burden of proof lies on the one who asserts, not the one who denies, still underpins every fair trial. Empires end; gradients, contracts and good concrete do not.

Pyramids of the Americas

People reached the Americas at least 15,000 years ago, and after that their societies developed with almost no contact with Eurasia. Yet they arrived at many of the same answers: farming, cities, monumental pyramids, writing and precise astronomy. At Caral in Peru's Supe valley, platform mounds and sunken plazas rose around 2600 BC, about when Egypt built its first pyramids. In Mexico the Olmec carved colossal basalt heads from about 1200 BC, and Teotihuacan, with its Pyramid of the Sun, housed perhaps 100,000 people around AD 500, including whole neighbourhoods of migrants from Oaxaca.

The Maya of southern Mexico and Central America built rival city-states such as Tikal, Calakmul, Copán and Palenque, at their height in the Classic period of about AD 250 to 900. Their script, mixing word signs with syllables, was cracked mainly between the 1950s and the 1980s, building on Yuri Knorozov's insight that it was partly phonetic and Tatiana Proskouriakoff's discovery that monuments recorded real rulers' lives. We can now read the career of K'inich Janaab' Pakal of Palenque, who took the throne aged 12 in AD 615 and was buried in 683 beneath the Temple of the Inscriptions, where Alberto Ruz found his jade-masked body in 1952. A laser survey from the air over Guatemala in 2018 revealed more than 60,000 structures under the forest, implying far denser populations than anyone had thought.

Maya scribes counted in base 20 and used a shell-shaped sign for zero in their Long Count calendar by the early centuries AD, independently of India. The Long Count cycle that ended on 21 December 2012 marked a calendar rollover, not a prophecy of doom. Astronomers at Chichén Itzá and elsewhere tracked Venus closely enough to forecast its appearances decades ahead.

Daily life was built on maize. Chemical signatures in bones show it made up most of the diet, and soaking it in lime, a process called nixtamalisation, released niacin and prevented the deficiency disease pellagra. Late Classic skeletons from Copán show widespread childhood illness and poor nutrition as the valley grew crowded. Cacao, whipped into a frothy drink, left residues in painted vessels. Later, the Mexica, or Aztecs, founded Tenochtitlan on an island in Lake Texcoco around 1325; by 1519 it may have held 200,000 people, fed partly from chinampas, raised garden plots built in the shallows.

Did you know? Mesoamericans made little wheeled toy animals but never used wheels for transport, having no horses or oxen to pull carts.

Spanish conquest and epidemics after 1519 devastated these societies, but they never vanished. Some six million people speak Mayan languages today, and maize, tomatoes, chillies and chocolate from Mesoamerica now feed the planet. The Americas prove that civilisation is no lucky accident: given fertile land, good crops and time, humans keep inventing it.

When Empires Fall

Every empire in this part of the story ended. In AD 476 the Germanic general Odoacer deposed the teenage emperor Romulus Augustulus and sent the imperial regalia to Constantinople, an event so quiet that few at the time thought the world had changed. Han China had already split into the Three Kingdoms in AD 220. In the 9th century the great Classic Maya cities of the southern lowlands emptied one by one. Historians debate whether "fall" is even the right word; many prefer "transformation", and the eastern Roman Empire endured for almost another thousand years, until 1453.

Overreach is part of the answer. Long frontiers cost money and soldiers, and when tax revenue fell short, rulers cheated. By the 270s the Roman silver coin, the antoninianus, contained only a few per cent of silver, and prices soared. In Han China, powerful landlords sheltered peasants from the tax register, court factions and eunuchs fought for control, and in AD 184 the Yellow Turban rebellion, led by the faith healer Zhang Jue, mobilised hundreds of thousands of desperate farmers.

Disease and climate, now read in genomes and ice, did the rest. The Antonine Plague, from AD 165, described by the physician Galen, was probably smallpox and may have killed millions. The Plague of Justinian, from 541, has been confirmed by ancient DNA from victims' teeth in Bavarian graves as Yersinia pestis, the bacterium of the Black Death. Volcanic eruptions in 536 and 540 dimmed the sun and chilled the northern hemisphere, leaving thin tree rings from Ireland to Mongolia. In the Maya lowlands, lake sediments record severe droughts between about 800 and 1000.

For ordinary people, collapse was measured in loss. The city of Rome, home to perhaps a million in Augustus' day, had shrunk to a few tens of thousands by the 6th century, its aqueducts cut. In post-Roman Britain, mass-produced pottery and coin use vanished within a generation or two, and the archaeologist Bryan Ward-Perkins has shown that cattle bones shrank back to pre-Roman sizes. In China, a census of AD 280 counted only about 16 million people against the Han's 57.7 million, though many had fled the tax rolls rather than died.

Did you know? The "Byzantines" never used that name: they called themselves Romans, and the label was popularised by Western scholars a century after their empire ended.

Yet much survived. Latin lived on in the Church, Roman law in Constantinople, Confucian learning in the courts of the Sui and Tang, and Maya communities in the northern Yucatán and the highlands. The forces that broke these empires, pandemics, climate shocks, debt and the strain of defending everything at once, are the same pressures governments manage today. No empire is permanent; what endures are the people who live through its end and the ideas they carry forward.

The Axial Age

Somewhere between about 800 and 200 BC, in places that knew little or nothing of one another, people began asking a new kind of question. Not only "which god must I feed?" but "how should I live, and what makes a person good?" In 1949 the German philosopher Karl Jaspers called this stretch the Axial Age, because so much of later human thought seems to turn on it like a wheel on its axle.

The cast is remarkable. In the kingdom of Judah, prophets such as Amos, Isaiah and Jeremiah thundered that God cared less about sacrifices than about how the poor were treated. On the Ganges plain, the Buddha and Mahavira, founder of Jainism, left comfortable homes to search for an end to suffering. In the small Chinese state of Lu, Confucius (551–479 BC) taught that kindness and good manners could hold a society together. In Athens, Socrates questioned everyone in the marketplace until the city put him to death in 399 BC.

How do we know them? Mostly through students. Socrates, the Buddha and Confucius wrote nothing that survives; we meet them in Plato's dialogues, in Buddhist scriptures first written down centuries later in Sri Lanka, and in the Analects, compiled by Confucius's followers. Historians debate how neat the "age" really was, and some argue Jaspers drew a tidy circle around untidy changes. Yet the overlap is real enough to need explaining.

The likeliest explanation lies in ordinary lives. Iron tools, coins and growing towns pulled people away from village kin and into crowds of strangers. Old local gods and blood loyalties no longer settled every quarrel. Merchants, scribes and townspeople needed rules that worked between people who were not family, and teachers who could explain why. Writing let arguments outlive their authors and travel.

Did you know? The Buddha, Confucius and Mahavira may well have been alive in the same decades of the fifth century BC, yet there is no evidence any of them ever heard of the others.

The answers differed, but they shared a turn inward. Each tradition asked people to examine their own minds and motives, to treat strangers with fairness and to see themselves as moral beings, not just members of a tribe. Ideas like the Golden Rule, inner self-control and the dignity of the questioner all date from these centuries.

Most of the world's people still live inside one of these frameworks, whether they pray, meditate, argue in a seminar or simply try to be decent to a stranger. The questions asked by a handful of teachers 2,500 years ago remain the ones we ask at three in the morning.

The Vedic Traditions

Around 1500 BC, poet-priests in north-west India began composing hymns in an early form of Sanskrit. Collected as the Rigveda, its 1,028 hymns praise fire, storm and dawn, and the god Indra, slayer of the serpent who held back the rivers. From these roots grew the family of traditions we now call Hinduism, a word outsiders first used for the people beyond the Indus. Many followers prefer Sanatana Dharma, the eternal way.

For a thousand years the Vedas were not read at all. They were learnt by heart, syllable by syllable, by boys trained in priestly families, using memory techniques such as reciting words forwards, backwards and in interlocking patterns. Linguists can compare the language with Old Persian and Greek, and the texts' hymns to horses and chariots fit what archaeologists know of the period. Historians still debate exactly how and when the Vedic peoples and the older cities of the Indus Valley met.

Then the questions deepened. In the Upanishads, written down from around 800 BC, teachers in forest retreats asked what lies beneath all the gods. Their answer was startling: Brahman, the single reality behind everything, is one with atman, the inner self. A student named Shvetaketu is told, in a famous line, tat tvam asi: "you are that." Ideas of karma and rebirth took shape in the same centuries.

Later came the great epics. In the Bhagavad Gita, part of the vast Mahabharata, the god Krishna counsels the warrior Arjuna on a battlefield and lays out three paths to the divine: selfless action, knowledge and loving devotion. Devotion swept India in the bhakti movements of the Middle Ages, when poets such as the Tamil saint Andal and the Rajput princess Mirabai sang to God in everyday languages, not priestly Sanskrit. Reformers from the Buddha to B. R. Ambedkar also challenged the hierarchy of caste that grew up alongside these texts.

Did you know? Vedic chanting was preserved so precisely by memory that UNESCO recognised it in 2003 as a masterpiece of the world's oral and intangible heritage.

What emerged was not one church with one creed but a vast conversation: thousands of gods understood by many as faces of one truth, and room for the philosopher, the farmer at a village shrine and the singer lost in devotion. Around 1.2 billion people live within this tradition today, and it gave the world yoga, the idea of karma and festivals such as Diwali. A Rigveda verse put it best: truth is one, though the wise call it by many names.

The Middle Way

Sometime in the fifth century BC, a young man named Siddhartha Gautama walked away from a life of comfort in the foothills of the Himalayas. Tradition says he had been sheltered in a palace until he saw, for the first time, an old man, a sick man and a corpse. He tried the opposite extreme, starving himself until, the stories say, he could feel his spine through his stomach. Neither worked. Sitting beneath a fig tree at Bodh Gaya, he found a path between indulgence and self-torture: the Middle Way. He became the Buddha, "the awakened one".

His first sermon, at Sarnath near Varanasi, set out Four Noble Truths with the clarity of a doctor's diagnosis. Life involves dukkha, suffering or dissatisfaction. Its cause is tanha, craving or thirst. It can cease. And there is a path to that cessation: the Noble Eightfold Path of right view, intention, speech, action, livelihood, effort, mindfulness and concentration. The goal is nirvana, literally "blowing out", like a flame that has no more fuel.

Our evidence is unusually layered. The teachings were memorised by monks and written down in Sri Lanka in the first century BC, on palm leaves. Scholars debate the Buddha's exact dates, but most now place his death around 400 BC. Hard evidence of the faith's spread comes from the rock edicts of the Indian emperor Ashoka, who, sickened by the slaughter of his war in Kalinga around 261 BC, carved messages of non-violence and tolerance across his empire.

The Buddha's practical genius was to found a community, the sangha, of monks and, unusually for the time, nuns. Monasteries became schools, libraries and hospitals. Missionaries and merchants carried the teaching to Sri Lanka, along the Silk Roads to China, then to Korea, Japan, Tibet and South-East Asia. The Chinese monk Xuanzang walked to India in 629 and returned sixteen years later with some 650 texts, which he spent the rest of his life translating.

Did you know? The oldest dated printed book in the world is a Buddhist scripture: a copy of the Diamond Sutra printed in China in 868, found in a sealed cave at Dunhuang.

Today around 500 million people are Buddhists, and many more borrow its tools. Mindfulness courses in hospitals, offices and schools grew from Buddhist meditation, adapted in the 1970s by the American doctor Jon Kabat-Zinn. The Buddha's core insight, that much of our misery comes from wanting and clinging, sounds as modern as a therapist's office. He did not promise a god to rescue us, only a method to change the mind that suffers.

One God

The ancient Near East was crowded with gods. Canaanites honoured Baal the storm god and El the father of gods; Babylon had Marduk; Egypt had Amun-Ra and hundreds more. The people of Israel and Judah, hill farmers on the edge of great empires, began much like their neighbours. Inscriptions found at Kuntillet Ajrud in Sinai, from around 800 BC, even bless travellers by "Yahweh and his Asherah", a goddess later condemned by the prophets.

Over several centuries, Israel's worship narrowed to one God, Yahweh, bound to his people by a covenant, a binding agreement with laws attached. Then came disaster. In 586 BC the Babylonians destroyed Jerusalem and its temple and carried much of its elite into exile. Many historians believe the shock helped turn worship of one god among many into true monotheism. A prophet of the exile, whose words are preserved in the Book of Isaiah, insisted there was no other god at all: the God of a defeated people ruled every nation, Babylon included.

This God was unusual in another way: he cared about ordinary behaviour. The Ten Commandments forbid murder, theft and lying in court. The weekly Sabbath gave a day of rest to everyone, including servants, foreigners and working animals, an astonishing idea in a world without weekends. Laws in Deuteronomy protect widows, orphans and strangers and leave the edges of fields unharvested for the poor. Kings were not gods, and prophets such as Nathan could rebuke King David for adultery and murder.

How do we know? Through the Hebrew Bible, assembled and edited over centuries, and through archaeology. Two tiny silver scrolls found in a tomb at Ketef Hinnom in Jerusalem, from around 600 BC, carry the priestly blessing still used in synagogues and churches. Papyri from a Jewish garrison on the island of Elephantine in Egypt show exiled families keeping the Passover in the fifth century BC.

Did you know? In 1947 a Bedouin shepherd searching for a stray goat near the Dead Sea found clay jars holding scrolls, including a complete Book of Isaiah about 1,000 years older than any Hebrew copy known before.

The idea proved explosive. Judaism survived exile, conquest and scattering, carried by families, the Sabbath table and the study of texts rather than an army. From it grew Christianity, and later Islam took up the same God of Abraham. Together these faiths count well over four billion followers. The notions that every person is made in God's image, that rulers answer to a higher law and that everyone deserves a day of rest began with a small, battered people who refused to share their God.

Reason as a Tool

In the Greek cities of the sixth century BC, a few people tried explaining the world without stories of the gods. Thales of Miletus suggested everything was made of water; Herodotus later credited him with predicting a solar eclipse, conventionally dated to 585 BC. The answers were often wrong, but the method was new: make a claim, give reasons, and let others pick holes in it.

In Athens, Socrates (c. 470–399 BC) turned the picking of holes into an art. A stonemason's son with a famously snub nose, he wandered the marketplace asking experts to define the things they claimed to know. In Plato's dialogue Euthyphro, a man confident about piety says it is what the gods love. Socrates asks: what if the gods disagree? Is something good because the gods love it, or do they love it because it is good? Most conversations end in aporia, honest puzzlement. This Socratic method, testing a claim against hard cases, is still how good teachers, lawyers and scientists work.

It cost him dearly. In 399 BC a jury of around 500 citizens convicted him of impiety and corrupting the young, and he drank hemlock in prison. In Plato's account of his defence, the Apology, he says that the unexamined life is not worth living.

His pupil Plato founded the Academy around 387 BC, a school in a grove outside Athens that lasted, in one form or another, for some three centuries. Plato's student Aristotle, a doctor's son from northern Greece, went further: he founded his own school, the Lyceum, in 335 BC, and set out the rules of logic, including the syllogism. He also looked hard at nature. On the island of Lesbos he studied sea creatures and described around 500 kinds of animal, noting correctly that dolphins breathe air and suckle their young.

Did you know? For a few years Aristotle was tutor to a teenage prince of Macedon, the future Alexander the Great.

Greek reason had blind spots. Aristotle defended slavery and thought women inferior to men, and Athens' democracy excluded women, slaves and foreigners. Yet the tools outlived the prejudices. Hypatia of Alexandria taught mathematics and philosophy until a Christian mob killed her in AD 415; centuries later Arabic and Latin scholars studied Aristotle so closely they simply called him "the Philosopher".

Every time a court cross-examines a witness, a scientist submits a paper for peer review or a student asks "how do you know?", the old Athenian habit is at work. Reason is not a creed but a tool, and its sharpest edge is turned on our own certainties.

The Christian Faith

Around AD 30, a Jewish teacher from Galilee named Jesus of Nazareth was crucified by the Roman authorities in Jerusalem. His followers, a few dozen fishermen, women and villagers, proclaimed that he had risen from the dead. Within three centuries their movement had reached every corner of the Roman Empire; today around 2.4 billion people, nearly a third of humanity, call themselves Christians.

Our earliest sources are letters. Paul, a Jewish tentmaker who had persecuted the movement, wrote to small congregations in the AD 50s, and his letters are older than any of the Gospels. Roman writers noticed too. Around AD 112 the governor Pliny the Younger wrote to the emperor Trajan asking what to do with Christians who met before dawn to sing hymns and would not worship the emperor's image.

The faith spread through ordinary homes. There were no church buildings at first: believers met in houses hosted by people such as Lydia, a dealer in purple cloth in Philippi, and Phoebe of Cenchreae, whom Paul commends as a deacon. Its message reached slaves, women and the poor. When plagues struck, Christians often nursed the sick, including non-Christians, while others fled, and many historians think this care, along with high birth rates, helped the movement grow.

Persecution came in waves. In 203 a young mother named Perpetua was executed in the arena at Carthage; her prison diary is one of the earliest surviving writings by a Christian woman. Then everything changed. The emperor Constantine backed the faith and, with his co-emperor, issued the Edict of Milan in 313 granting toleration, and by 380 Christianity was the empire's official religion. In Egypt's desert, Antony and others pioneered monasticism; around 530 Benedict wrote a Rule for monks that balanced prayer, work and study.

Did you know? Christianity reached the kingdom of Aksum in Ethiopia in the fourth century, earlier than most of northern Europe, and the Ethiopian church has kept its own ancient traditions ever since.

Missionaries carried it further: Patrick to Ireland in the fifth century, Cyril and Methodius to the Slavs, who invented an alphabet to write the Bible in their language. Christian ideas shaped hospitals, universities, and art from icons to cathedrals, and the year numbers we use come from a sixth-century monk, Dionysius Exiguus, who counted from the birth of Christ. They also shaped crusades, inquisitions and wars of religion, and the same scriptures were quoted by slaveholders and abolitionists alike. Today the faith's centre of gravity has shifted south, to Africa and Latin America. A movement that began in borrowed living rooms still meets, more often than not, wherever people gather.

The Rise of Islam

Around AD 610, a merchant of Mecca named Muhammad, then about forty, began to receive what Muslims believe were revelations from God, brought by the angel Gabriel. Mecca was a trading town in western Arabia whose shrine, the Kaaba, held idols of many tribal gods. Muhammad's message was stark: there is no god but God, and every person, rich or poor, will answer for how they treated orphans, widows and the weak.

The Meccan elite did not welcome it. In 622 Muhammad and his followers moved to Medina, a journey called the hijra that marks year one of the Islamic calendar. By 630 he returned to Mecca at the head of an army, and tradition says he cleared the Kaaba of its idols. When he died in 632, much of Arabia was united. Within a century Arab armies had built an empire from Spain to the Indus, though conversion of the conquered peoples was gradual and took centuries.

The revelations were gathered into the Quran, compiled into a standard text under the caliph Uthman around 650. Its language shaped Arabic itself. The faith rests on five simple practices, the Five Pillars: declaring faith, praying five times a day facing Mecca, giving alms, fasting in Ramadan and, for those who can, making the Hajj pilgrimage. They reshape the day, the year and the whole of a life. A labourer and a sultan pray side by side, in the same rows, with no priest between them and God.

Did you know? In 2015 radiocarbon tests on two leaves of a Quran manuscript in Birmingham dated the parchment to between about 568 and 645, placing them among the oldest Quranic texts known.

The Hajj turned Mecca into a meeting place for the world. Pilgrims walk seven times around the Kaaba, drink from the well of Zamzam and hurry seven times between the hills of Safa and Marwa, remembering Hagar's search for water for her son Ishmael. In 1324 Mansa Musa, king of Mali, passed through Cairo on his way to Mecca with so much gold that, chroniclers said, its value there fell for years. In 1325 the young Moroccan scholar Ibn Battuta set out for the Hajj and kept travelling for almost thirty years, to India, China and West Africa.

A shared faith, language and law let a merchant from Morocco trade, marry and study in Persia or Java. Today around two billion Muslims live on every continent; the largest Muslim country is Indonesia, which Arab armies never reached. Five times a day, as the sun moves around the planet, a wave of prayer follows it, every worshipper facing the same small stone building.

The House of Wisdom

In the early ninth century, Baghdad was perhaps the largest city on Earth, the round capital of the Abbasid caliphs. There, under caliphs such as al-Mamun (reigned 813–833), scholars gathered at the Bayt al-Hikma, the House of Wisdom. Historians debate whether it was a grand academy or mainly a palace library, but the work done around it is not in doubt: one of the greatest translation efforts in history.

The raw material was Greek. Aristotle on logic and nature, Galen on medicine, Euclid on geometry and Ptolemy on the stars were sought out, bought and copied. A key figure was Hunayn ibn Ishaq (809–873), a Christian doctor from Iraq who translated more than a hundred works of Galen into Syriac and Arabic, checking several manuscripts to find the best text. Translators were Christians, Jews, Persians and Muslims working side by side, and paper, learnt from Chinese papermakers, made books far cheaper than parchment.

Translation was only the beginning. Around 820 al-Khwarizmi wrote a handbook on solving equations whose title gave us the word algebra; his own name, mangled in Latin, became algorithm. He also helped spread the Indian numerals we use today, with their zero. In Cairo, Ibn al-Haytham argued in his Book of Optics (c. 1011–1021) that we see because light enters the eye, and tested ideas with experiments. In Cordoba, the surgeon al-Zahrawi described and drew some 200 surgical instruments. Ibn Sina's Canon of Medicine was still taught in European universities in the 1600s.

Learning reached well beyond the court. In 859 Fatima al-Fihri, a merchant's daughter, founded a mosque in Fez that grew into the University of al-Qarawiyyin. In tenth-century Aleppo, Mariam al-Ijliya built astrolabes for telling the time and finding the direction of prayer. Hospitals in Baghdad and Cairo treated patients regardless of wealth, and doctors were examined before they could practise.

Did you know? Many stars in the night sky still carry Arabic names, including Aldebaran, Betelgeuse and Vega, passed to Europe through translated star catalogues.

The knowledge flowed on. After Toledo fell to Christian Castile in 1085, scholars poured into its libraries; Gerard of Cremona, who died there in 1187, translated more than 70 Arabic works into Latin. In 1202 Fibonacci's Liber Abaci taught European merchants the Hindu-Arabic numerals. Without this relay, the Renaissance would have had far less to be reborn from. Every time you use an algorithm, write a zero or take medicine tested by experiment, you are using the inheritance of a city of translators.

Harmony and Order

Confucius, or Kong Fuzi, "Master Kong" (551–479 BC), was a minor official in the small state of Lu during a violent age of warring rulers. He never founded a religion and said little about gods or the afterlife. Asked about serving spirits, he replied, in the Analects, that we cannot yet serve people, so how can we serve spirits? His concern was this life: how families and states could live in harmony.

His answer started at home. Filial piety, xiao, meant caring for parents in life and honouring them after death. Ren, humaneness, was the inner quality of a good person; li, ritual and courtesy, was its outward form, from bowing correctly to mourning properly. His follower Mencius later described five key relationships: ruler and subject, father and son, husband and wife, elder and younger brother, and friend and friend. Each carried duties in both directions, and a ruler who failed his people could lose the "mandate of Heaven".

We know his teaching through the Analects, sayings collected by his disciples. In one, asked for a single word to live by, he answers "reciprocity": do not impose on others what you would not want for yourself. Under the Han dynasty, from the second century BC, Confucian classics became the curriculum of the state. The woman historian Ban Zhao, around AD 100, wrote Lessons for Women, urging humility on wives while insisting that girls, like boys, should be educated.

The idea that learning, not birth, should qualify officials reached its fullest form in the imperial examinations, used from 605 until 1905. Candidates memorised the classics and wrote essays in cramped cells; the Jiangnan exam hall in Nanjing had around 20,000 of them. Families saved for years to educate one promising son, and success could lift a whole clan. Failure was common, and some men sat the exams into old age.

Did you know? Kong Demao, said to be a 77th-generation descendant of Confucius, lived until 2021, and the Kong family keeps one of the longest recorded family trees in the world.

The ideals had costs: rigid hierarchy, and wives expected to obey husbands and sons. Yet they shaped China, Korea, Japan and Vietnam for 2,500 years. You can see them in the reverence for teachers, in ancestor rites at Lunar New Year and Korea's Chuseok, and in China's gaokao exam, which more than 13 million students sit each June. Confucius built no temple; his altar was the family table, and his scripture a well-taught child.

The Search for Meaning

No human society has ever been found without some way of answering the big questions: why we suffer, how we should live, what we owe one another and what happens when we die. The search seems as old as our species. Around 100,000 years ago, people at Qafzeh in what is now Israel buried their dead with care, one child with a deer's antlers in its arms. Around 9500 BC, hunter-gatherers raised the carved stone pillars of Göbekli Tepe in Turkey, possibly the oldest monumental gathering place known, before anyone farmed nearby.

The traditions in this part of the book gave strikingly different answers. Asked why we suffer, the Buddha pointed to craving; Confucius to broken relationships and lost courtesy; the Hebrew Book of Job to a mystery beyond human understanding; Socrates to ignorance of what is truly good. Asked how to live, they offered a middle path, a web of family duties, a covenant with God and a life of virtue. On death they differ widely, from rebirth and release to resurrection and judgement, while some Greek thinkers, following Epicurus, said death is simply nothing to fear.

Yet on our duty to others they rhyme. Confucius taught: do not impose on others what you would not want for yourself. The Jewish sage Hillel, asked to sum up the Torah while standing on one foot, said, according to the Talmud, that what is hateful to you, you should not do to your neighbour; the rest is commentary. Jesus taught to do to others as you would have them do to you. Versions of this Golden Rule appear in Hindu, Buddhist and Islamic teaching too. In southern Africa, the idea of ubuntu says a person is a person through other people.

The search has never stopped. In 1946 the psychiatrist Viktor Frankl, who had survived Auschwitz, published the book known in English as Man's Search for Meaning, arguing that people can endure almost anything if they have a reason to. Today, according to the Pew Research Center, around a quarter of the world's people say they belong to no religion, yet many still meditate, volunteer, light candles for the dead or look for meaning in art, nature and science.

Did you know? Göbekli Tepe's carved pillars are around 7,000 years older than the earliest pyramids of Egypt.

Perhaps no single answer will ever satisfy everyone. But the questions themselves bind us: every grieving parent, every teenager asking "what's the point?", every scientist staring at the stars stands in a line that runs back to those careful burials. To search for meaning may be the most human thing we do.

The Silk Roads

Around 138 BC the Han emperor Wudi sent an envoy, Zhang Qian, west into Central Asia to find allies against the nomadic Xiongnu. He was captured, held for about ten years, escaped, and came home with reports of horses, grapes and cities nobody in China had heard of. Within a few generations caravans were linking the Han world to Persia, India and, at the far end, Rome. The routes we call the Silk Roads ran for some 6,000 kilometres across deserts and mountain passes, and they stayed busy, on and off, for over a thousand years.

Almost nobody walked the whole way. Goods moved in relays, sold on at oasis cities such as Dunhuang, Kashgar, Samarkand and Merv, each merchant covering one stretch. The masters of the middle were the Sogdians, Iranian-speaking traders from around Samarkand. In 1907 the archaeologist Aurel Stein found a mailbag of their letters, written around AD 313, lost in a watchtower near Dunhuang. One is from a woman called Miwnay, stranded there with her daughter after her husband left, telling him she would rather have married a dog or a pig. It is trade history as it was lived: debts, delays and families stretched across a continent.

Silk went west, prized in Rome so much that moralists such as Pliny the Elder grumbled about the drain on the empire's wealth. Horses, glass, silver and gold went east, and Han China took in grapes and alfalfa from Central Asia. The real cargo was people and ideas. Buddhist monks carried scriptures into China from the first century AD; the pilgrim Xuanzang walked to India and back between 629 and 645 to fetch better texts. Nestorian Christians, Manichaeans and later Muslims followed the same tracks. Bactrian camels, able to carry a heavy load for weeks on little water, made the whole system work.

Did you know? No traveller ever used the name. "Silk Road" was coined in 1877 by the German geographer Ferdinand von Richthofen, centuries after the caravans stopped.

The sealed Library Cave at Dunhuang, opened in 1900, held tens of thousands of manuscripts in more than a dozen languages, including the Diamond Sutra of 868, the oldest dated printed book. Graves tell the same story: the tomb of the Sogdian An Jia, buried in Xi'an in 579, shows him feasting with Turkic chiefs. Germs travelled too, and the same networks would later carry plague. And a popular myth can be dropped: Marco Polo did not bring pasta to Italy.

Today China's Belt and Road project borrows the old name, fibre-optic cables follow some of the same corridors, and a peach or a bowl of noodles may owe its route to a camel. The Silk Roads taught a lesson every network has relearned since: what travels furthest is not the cargo but the ideas riding with it.

The Eastern Empire

In 330 the emperor Constantine dedicated a new capital on the Bosporus, on the site of the Greek town of Byzantium, and named it after himself. When the last western emperor, the boy Romulus Augustulus, was deposed in 476, Rome's story in the west ended. In the east it carried on for almost another thousand years. Its people never called themselves Byzantines. They were Romans, Rhomaioi, speaking Greek, worshipping as Christians and governed by Roman law.

Constantinople was the largest city in Christian Europe for most of those centuries, perhaps half a million people at its sixth-century height. Bread was handed out to citizens, as in old Rome, and the crowd's real passion was chariot racing. Fans of the Blues and the Greens rioted together in 532, in the Nika riots, and nearly toppled the emperor Justinian; the historian Procopius says his wife Theodora, a former actress, talked him out of fleeing. The army trapped and killed tens of thousands of rioters in the Hippodrome. Justinian then rebuilt the burned centre, crowning it in 537 with the vast dome of Hagia Sophia.

His lawyers did something more lasting. Between 529 and 534 they boiled a millennium of Roman law down into the Corpus Juris Civilis. Rediscovered in Italy around 1070, it became the backbone of law across continental Europe and, through it, Latin America. Justinian's reign also brought the first recorded pandemic of bubonic plague, from 541. Historians long argued about what the disease was; ancient DNA from sixth-century graves in Bavaria has since confirmed Yersinia pestis, the same germ as the later Black Death.

The city survived because of its Theodosian Walls, built in the 410s: a moat, an outer wall and a towering inner wall with 96 towers running about six kilometres from sea to sea. Behind them the Romans kept Greek learning alive in copied manuscripts, and invented weapons such as Greek fire, a sticky burning liquid that could not easily be put out, which reportedly helped them burn Arab fleets in the 670s. In 863 the brothers Cyril and Methodius set out to convert the Slavs, and the alphabet created for that mission led to Cyrillic. The Princess Anna Komnene, writing her Alexiad in the 1140s, became one of the first known women historians.

Did you know? The name "Byzantine Empire" was popularised by the German scholar Hieronymus Wolf in 1557, more than a century after the empire had gone.

Crusaders sacked the city in 1204, and in 1453 Ottoman cannon finally broke the walls. By then Greek scholars had carried Plato and Homer to Italy. Every Russian or Bulgarian sign in Cyrillic, every civil-law contract and every Orthodox church service is a piece of the empire that refused to fall when Rome did.

The Feudal Bargain

When Charlemagne's empire splintered in the ninth century and Viking, Magyar and Arab raiders struck Europe's coasts and rivers, kings were too weak and too far away to protect most people. Protection became local. A powerful man granted land, a fief, to a warrior, who knelt, placed his hands between his lord's and swore loyalty. This act of homage created a vassal: he owed military service, counsel and sometimes money; the lord owed him protection and justice. Bishops and abbots held land on similar terms.

Underneath the knights were the people who did the work, and most Europeans were peasants. Many were serfs or villeins, legally tied to the manor. Typical duties were to work the lord's land for set days each week, to hand over part of the harvest, to grind grain at the lord's mill and pay for the privilege, and to ask permission to marry off a daughter. In return they had a hut, strips in the open fields and a claim to the lord's protection. Around the year 1000, writers described society as three orders: those who pray, those who fight and those who work.

We can count these people. William the Conqueror's Domesday Book of 1086 recorded around 268,000 heads of households in England: villeins, smallholders called bordars, and about a tenth listed as slaves. Bones fill in the rest. At Wharram Percy, a deserted village in Yorkshire, archaeologists excavated hundreds of skeletons that show heavy lifting and worn joints from young ages, and children growing more slowly than children do now. A diet of pottage, coarse bread and ale kept people working but rarely well fed.

Did you know? No one in the Middle Ages ever used the word "feudalism". It was coined by lawyers and scholars in the seventeenth and eighteenth centuries.

That matters, because historians now debate whether "feudalism" was ever one system at all. In 1974 Elizabeth Brown called the idea a tyrannical construct, and Susan Reynolds later showed how differently fiefs and vassals worked from place to place. Similar bargains appeared elsewhere: in Japan from the twelfth century, warriors served lords in return for income from land, and samurai loyalty became a code of its own.

The bargain loosened as money, towns and royal courts grew, and plague would later crack it wide open. Yet its traces are everywhere. English property law still speaks of land held "in fee", from the old fief. The idea that power comes with duties, and that even a lord owes something to those below him, grew out of these oaths. So did the stubborn notion that a promise between unequals can still bind both sides.

The Viking Age

On 8 June 793, raiders from the sea attacked the monastery of Lindisfarne off England's northeast coast. The scholar Alcuin wrote that such a terror had never before appeared in Britain. For the next two and a half centuries Scandinavians, known to us as Vikings, raided, traded and settled across a quarter of the globe. Their secret was the longship: light, shallow and fast under sail or oar, able to cross open sea and then row far up rivers.

Most Norse people were farmers, and most voyages were about land and trade as much as loot. Swedes known as the Rus' rowed and dragged their boats down the Volga and Dnieper to trade furs, honey and enslaved captives for silver. Islands such as Gotland have yielded tens of thousands of Islamic silver coins, and the Spillings hoard alone weighed some 67 kilograms. In 922 the Arab envoy Ibn Fadlan met Rus' traders on the Volga and described a chieftain's ship funeral in grim detail. Others went on to Constantinople, where Norse guards served the emperor and someone carved the name Halfdan in runes into a parapet of Hagia Sophia.

Westward they found empty islands. Settlers reached Iceland around 870 and founded the Althing, an open-air assembly, in 930. Erik the Red led colonists to Greenland around 985. His son Leif Eriksson sailed further, to a land the sagas call Vinland. For centuries it sounded like legend, until in 1960 Helge Ingstad and Anne Stine Ingstad found Norse buildings at L'Anse aux Meadows in Newfoundland. In 2021 scientists used a burst of cosmic radiation recorded in tree rings to show that wood there was cut with metal tools in 1021. The sagas say a woman named Gudrid gave birth to a son, Snorri, in Vinland.

DNA has blurred the old picture of blond invaders. A 2020 study of more than 400 Viking-age genomes found a great deal of mixing: some people buried as Vikings in Scotland were locals, and many Scandinavians had dark hair. A warrior grave at Birka in Sweden, long assumed to be a man's, turned out in 2017 to hold a woman; what her role was is still debated.

Did you know? No Viking helmet with horns has ever been found. The image comes largely from nineteenth-century art and costumes for Wagner's operas.

By the eleventh century the Norse had become Christian kings, Norman dukes and Rus' princes, quietly folding into Europe. They left words: English speakers say "sky", "egg", "knife", "they" and "window", from the Norse for "wind eye", and towns ending in -by mark their farms. They also left the first proof that people from Europe and the Americas met, five centuries before Columbus, on a cold Newfoundland shore.

The Mongol Empire

In 1206, at an assembly on the steppe, a chieftain named Temüjin was proclaimed Genghis Khan. He had grown up an outcast after his father was poisoned, and he rebuilt Mongol society around loyalty rather than clan, organising warriors in units of ten, a hundred and a thousand. Mounted archers, each with several horses, could ride further and faster than any army they met. Within seventy years his sons and grandsons ruled from Korea to Hungary, the largest contiguous land empire in history.

The conquest was horrifying. Cities that resisted were often destroyed: Merv, one of the great cities of Central Asia, fell in 1221, and Persian chroniclers reported death tolls so high they are hard to believe. In 1258 Hulegu's army sacked Baghdad, killing the caliph and, by tradition, filling the Tigris with books. Northern China's population, judged from tax counts, fell by tens of millions between the Jin census and the first Yuan counts; historians debate how much was death and how much was flight, famine or people slipping off the registers.

Then the same empire made Eurasia unusually easy to cross. The yam, a relay system of post stations with fresh horses, carried messengers huge distances, and a metal tablet called a paiza worked like a passport. Merchants, envoys and craftspeople moved east and west, often by force: skilled workers were seized and resettled across the empire. The Flemish friar William of Rubruck reached the capital, Karakorum, in 1254 and found a Parisian goldsmith working there. Going the other way, the monk Rabban Sauma, born near Beijing, travelled to Europe in 1287 and met the pope and the English king Edward I.

Women held real power. Sorghaghtani Beki, a Christian widow, raised four sons who all became rulers, including Möngke and Kublai, and protected farmers and religions in her lands. Kublai's Yuan dynasty in China issued paper money and hosted Muslim astronomers, Tibetan monks and a Venetian named Marco Polo.

Did you know? A 2003 genetic study found a Y-chromosome lineage carried by about 8 per cent of men across a wide region of Asia, and suggested it may trace back to Genghis Khan's family. The link is still debated.

The open roads carried something deadly as well. The plague that would devastate Europe and the Middle East in the 1340s moved along Mongol trade routes. The empire split into rival khanates and the Yuan fell in 1368, but it left Russia's later rulers, India's Mughals and Central Asia's states all claiming its legacy. It also proved, at a terrible price, that a single connected Eurasia was possible.

The Great Mortality

In 1338 and 1339 a Christian community near Lake Issyk-Kul, in today's Kyrgyzstan, buried an unusual number of people under gravestones that blame a "pestilence". In 2022 scientists extracted plague DNA from their teeth and found a strain at the root of the pandemic that followed. Within a decade the bacterium Yersinia pestis, carried by fleas on rats and other animals and spread in its pneumonic form from person to person, had crossed Eurasia along routes the Mongols had opened. People called it the Great Mortality; the name Black Death came much later.

It reached the Black Sea port of Caffa in 1346, where the Genoese merchant colony was under siege, and Italian galleys carried it to Messina in Sicily in October 1347. In three years it swept through Europe, the Middle East and North Africa, killing perhaps a third to a half of Europe's people, and probably more in some places. In Cairo the historian al-Maqrizi later described corpses piled in the streets. The scholar Ibn Khaldun lost both his parents to it in Tunis. In Siena the chronicler Agnolo di Tura wrote that he buried his five children with his own hands.

Did you know? The word "quarantine" comes from the Venetian for forty days. The city of Ragusa, now Dubrovnik, ordered the first known isolation of ships and travellers in 1377, for thirty days.

We know its scale from tax records, wills, parish registers and the bodies themselves. At East Smithfield in London an emergency cemetery opened in 1348 was laid out in long, orderly trenches; DNA from its skeletons confirmed the germ in 2011. The horror bred blame as well as piety. Flagellants whipped themselves through German towns, and Jewish communities were falsely accused of poisoning wells: in Strasbourg in February 1349, hundreds of Jews were burned.

Then came the surprise. With so many dead, the survivors' labour suddenly became scarce and valuable. Wages rose, and many peasants ate more bread, meat and ale than their grandparents had. Lords tried to freeze pay: England's Ordinance of Labourers of 1349 and the Statute of 1351 ordered workers to accept old wages. Resentment boiled over in the Peasants' Revolt of 1381, when rebels entered London. The revolt was crushed, but serfdom in England faded within a few generations as landlords had to bargain with tenants.

The plague returned again and again for three centuries. It left Europe with public-health boards, sick certificates and quarantine, tools that every country reached for during COVID-19. It also left a lesson historians still argue over: a catastrophe that killed millions also made the lives of the survivors, briefly, better.

Gold and Salt

In the Sahara, salt was worth carrying across a desert. People and animals in the hot savannah to the south sweat it out and must replace it, while the mines at Taghaza, deep in the desert, cut it in great slabs. South of the Sahara lay something the north wanted just as badly: gold, panned and dug in the fields of Bambuk, Bure and later the Akan forests. Camel caravans of hundreds or thousands of animals linked the two, and the empires that controlled the meeting point grew rich.

The first was Ghana, described by the Andalusian geographer al-Bakri in 1068. The greatest was Mali, founded around 1235 by Sundiata Keita, whose story is still sung by griots, the hereditary bards of West Africa. Its most famous ruler, Mansa Musa, made the pilgrimage to Mecca in 1324 with a huge retinue. The Cairo official al-Umari recorded that Musa gave away so much gold in Cairo that its value there was still depressed years later. In 1375 a map made in Majorca, the Catalan Atlas, showed him enthroned in West Africa holding a golden nugget.

Musa brought back scholars and, by tradition, the architect Abu Ishaq es-Saheli, credited with the Djinguereber Mosque in Timbuktu, built of mud brick around 1327. The city became a seat of Islamic learning, with scholars teaching law, astronomy and medicine around mosques such as Sankore. The traveller Ibn Battuta visited Mali in 1352 and 1353. He praised its safety on the roads, was startled by how freely women mixed with men, and described Taghaza as a town where even the houses and mosque were built of salt slabs roofed with camel skins.

Songhai, under Sunni Ali, took Timbuktu in 1468 and became the largest of the three empires. Its scholars included Ahmed Baba, who was later deported to Morocco and wrote there about the books he had lost. The trade also had a darker cargo: enslaved people were marched north across the desert alongside the gold. In 1591 a Moroccan army armed with guns crushed Songhai at Tondibi.

Did you know? In 2012 and 2013, as armed jihadists held Timbuktu, librarians led by Abdel Kader Haidara smuggled hundreds of thousands of manuscripts south to Bamako in rice sacks and metal trunks.

Those manuscripts, on law, astronomy, medicine and poetry, overturn the old European claim that Africa had no written history. Salt caravans still cross the desert from the mines at Taoudenni, and modern Ghana and Mali took their names from medieval empires. The gold of Mali shaped how Europe and the Islamic world imagined Africa. Its libraries show what Africans themselves chose to remember.

The Ottoman Centuries

On 29 May 1453, after a siege of fifty-three days, the army of the twenty-one-year-old Sultan Mehmed II broke through Constantinople's land walls, helped by giant bronze cannon cast by a Hungarian engineer named Orban. The Roman Empire of the east was gone. Mehmed made the city, soon widely known as Istanbul, his capital, turned Hagia Sophia into a mosque and invited people back to repopulate it. The dynasty founded around 1299 by a Turkish chieftain named Osman now ruled an empire that would last until 1922.

It was run in an unusual way. Through the devşirme, the state took boys from Christian villages in the Balkans, converted them to Islam and trained them for service. The best became palace officials and even grand viziers; others joined the Janissaries, a salaried standing infantry at a time when most of Europe relied on feudal levies. The architect Mimar Sinan, taken from a village in Anatolia, rose this way to design hundreds of buildings, including the Süleymaniye Mosque, completed in 1557. For the families who lost their sons, the system was a grief; for the sons, it could be a ladder.

The empire peaked under Süleyman, who ruled from 1520 to 1566. Europeans called him the Magnificent; his subjects called him Kanuni, the lawgiver. His armies besieged Vienna in 1529, and his realm spread across southeastern Europe, the Middle East and North Africa. Christians and Jews lived under their own religious leaders and courts, an arrangement later called the millet system; historians debate how formal it was before the nineteenth century. When Spain expelled its Jews in 1492, Sultan Bayezid II welcomed many to Ottoman cities, and Salonica became a largely Jewish city.

We see ordinary lives through Ottoman paperwork. The tahrir surveys counted households and crops village by village, and local court records show women going to the kadı, the judge, to defend their property, sue for divorce or sell a house. Istanbul's first coffee houses opened in the 1550s and quickly worried the authorities, who suspected they bred gossip and dissent.

Did you know? Lady Mary Wortley Montagu, wife of the British ambassador, saw smallpox inoculation practised in Istanbul and had her son inoculated there in 1718, before promoting the method in England.

Defeats, debts and rising nationalism slowly hollowed the empire out, and after the First World War the sultanate was abolished in 1922. The Republic of Turkey followed in 1923. Its long shadow lies across the map, in the borders of the Balkans and the Middle East, and on the table: coffee, yoghurt, stuffed vine leaves and baklava are shared from Bosnia to Iraq. Six centuries of mixed rule left neighbours who still argue over who invented which dish.

The Columbian Exchange

When Columbus's ships reached the Caribbean in 1492, they reconnected two halves of the world that had been biologically separate for about ten thousand years. What followed was named in 1972 by the historian Alfred Crosby: the Columbian Exchange, the transfer of plants, animals, microbes and people across the Atlantic in both directions. It changed what almost everyone on Earth eats, and it killed more people than any war before it.

Westward went wheat, rice, sugar cane, bananas, horses, cattle, pigs, sheep and chickens. Within two centuries the peoples of the Great Plains, such as the Comanche, had made the horse the centre of a new way of life, hunting bison from horseback. Eastward came maize, potatoes, cassava, sweet potatoes, tomatoes, beans, peanuts, cacao, tobacco and chilli peppers. Maize and cassava became staples across much of Africa; sweet potatoes, reaching China in the 1590s, helped feed a growing population on poor hillsides; potatoes fuelled population growth in northern Europe and, later, Ireland's dangerous dependence on one crop.

The deadliest travellers were invisible. Peoples of the Americas had no immunity to smallpox, measles or influenza. Smallpox reached Mexico in 1520 and swept through Tenochtitlan during the Spanish siege. Later epidemics, known as cocoliztli, struck in 1545 and 1576; in 2018 researchers found DNA of a Salmonella bacterium in victims buried at Teposcolula-Yucundaa in Oaxaca. Across the Americas, populations fell by up to 90 per cent in many regions over the following century. Historians debate the starting numbers, but not the scale of the catastrophe. Some scholars think syphilis travelled the other way, a question still argued over.

Did you know? Before 1492 there were no chilli peppers in India, Thailand, Sichuan or Korea. The heat in their cuisines arrived from the Americas, mostly via Portuguese traders.

The exchange also moved people by force. As Indigenous workers died, European colonists turned to Africa for labour, especially on sugar plantations. Over roughly three and a half centuries, about 12.5 million enslaved Africans were embarked for the Americas, the largest forced migration in history. Their foods, music and faiths reshaped the Americas in turn.

Every kitchen is now a product of 1492. Italy's tomato sauce, Ireland's potatoes, Ghana's cassava, Hungary's paprika and the beef and wheat of Argentina all crossed an ocean. So did the scars: the demographic collapse of the Americas and the African diaspora are still written into the populations and politics of three continents. The world's dinner plate is global because the world was stitched together, at enormous human cost.

A Connected World

In the decades either side of 1500, a handful of voyages joined the oceans into a single system. Columbus crossed the Atlantic in 1492. In 1498 Vasco da Gama rounded Africa and reached Calicut in India. Between 1519 and 1522 a Spanish expedition led by Ferdinand Magellan sailed around the globe; Magellan himself was killed at Mactan in the Philippines in 1521 by the forces of the local chief Lapulapu, and only eighteen men returned to Spain with Juan Sebastián Elcano on the Victoria. For the first time, every inhabited continent except Australia was linked by regular sea routes.

The glue was silver. In 1545 a mountain of ore was found at Potosí in the Andes, and soon a city of well over 100,000 people grew at more than 4,000 metres. The labour came from Indigenous men forced into the mita, a draft of workers sent down the mines, where many died of accidents and mercury poisoning. Meanwhile Ming China, the world's largest economy, was switching its taxes to payment in silver, and its demand seemed bottomless. Historians think a large share of all the silver mined in the Americas ended up in China.

The final link opened in 1565, when the navigator Andrés de Urdaneta found winds to carry ships back east across the Pacific. From 1571, when Spain founded Manila, the Manila galleons sailed between Acapulco and the Philippines once or twice a year for two and a half centuries. Mexican silver went west; Chinese silk, porcelain and spices went east, then overland to Veracruz and on to Seville. Chinese and Japanese traders settled in Manila; Filipino and other Asian sailors stayed in Mexico, where they were known as chinos.

Did you know? The Spanish silver dollar, the "piece of eight", minted largely from American silver, circulated across Asia and the Americas and was legal tender in the United States until 1857.

People moved and mixed as never before, and so did their fates. Spanish colonial censuses and church registers record Indigenous, African, European and Asian ancestries side by side in cities like Mexico City and Lima. Earlier, between 1405 and 1433, the Ming admiral Zheng He had led huge fleets to East Africa, then China had stopped sending them; it was the Iberian ships that closed the loop.

From the 1500s, a price change in Potosí could be felt in Seville and Beijing, and a disease, a crop or a fashion could cross the planet in a generation. That is the world we still live in, with container ships, supply chains and pandemics running along the same ocean paths. Humanity had become one story, sharing both its rewards and its horrors.

The Printing Press

Around 1450 in Mainz, a goldsmith named Johannes Gutenberg combined several existing things into one machine that changed the human mind. He cast individual letters in a lead alloy using an adjustable hand mould, mixed an oil-based ink that clung to metal, and adapted the screw press long used for squeezing grapes and paper. By about 1455 his workshop had finished a Latin Bible of some 1,280 pages. Movable type was not new: Bi Sheng made clay type in China around 1040, and Korean printers produced the Jikji with metal type in 1377. But for alphabets of a few dozen letters, Gutenberg's system was fast, and Europe adopted it with startling speed.

We can follow that spread through the books themselves. Bibliographers have catalogued nearly every surviving edition printed before 1501, the incunabula, and they show presses working in more than 250 European towns by 1500, with millions of copies in circulation. William Caxton printed in Westminster from 1476; in Venice, Aldus Manutius sold small, portable classics set in a new italic type from 1501. A professional scribe might need months to copy a single Bible. A press crew could print hundreds of copies of a whole edition in the same time.

Printing reshaped ordinary lives. Compositors, pressmen, typefounders and booksellers formed a new urban trade, and in 1539 journeymen printers in Lyon went on strike over pay and hours, one of the earliest recorded strikes in Europe. Cheap pamphlets, almanacs, ballads and woodcut broadsheets reached people who had never owned a book. When Martin Luther's protest began in 1517, his short German tracts were reprinted across the Holy Roman Empire within weeks, turning a quarrel among clergy into a mass movement. Literacy climbed slowly, and historians measure it by counting how many brides and grooms could sign a marriage register rather than make a mark.

The press did not conquer everywhere at once. The Ottoman Empire, where scribes and calligraphers held revered status, licensed İbrahim Müteferrika to print books in Ottoman Turkish only in 1727, although Jewish, Armenian and Greek communities in Istanbul had printed for generations. In China, Korea and Japan, carved woodblocks already produced large runs cheaply and stayed dominant into the nineteenth century.

Did you know? Of roughly 180 Gutenberg Bibles printed, about 49 survive, and Gutenberg himself profited little: after a lawsuit in 1455 his financier, Johann Fust, took over much of the workshop.

Every newspaper, textbook, manifesto and web page descends from that wager on cheap, identical copies. The press made knowledge something that could be checked against the same page in another city, argued over, corrected and reprinted. It also made rumour and error travel faster, a problem every new medium since has inherited. Gutenberg gave humanity a memory that no single burning library could erase.

The Rebirth

In the 1340s the poet Petrarch hunted through monastery libraries for lost letters by Cicero and declared that the centuries since Rome had been an age of darkness. It was unfair to the medieval world, but the idea stuck. Over the next two centuries scholars and artists in the cities of Italy set out to recover classical learning and, in doing so, put the human being, body and mind, at the centre of their work. The age was later called the Renaissance, or rebirth; Giorgio Vasari had already written of a rinascita of the arts in his Lives of the Artists of 1550.

Its fuel was money and its spark, partly, disaster. The Black Death of 1348 killed perhaps half of Florence's people, and survivors who inherited land, wages and workshops had more to spend. Banking families such as the Medici paid for chapels, libraries and sculpture as advertisements of piety and power. Greek manuscripts arrived with Byzantine scholars, especially after Constantinople fell in 1453, and many classical texts had been preserved and debated by Islamic scholars such as Ibn Rushd, known in Latin as Averroes. We know Florentine households in rare detail thanks to the catasto of 1427, a tax survey listing ages, family members, debts and property for tens of thousands of people.

The new art looked hard at people. Around 1415 the architect Filippo Brunelleschi demonstrated linear perspective, and Masaccio's Holy Trinity of about 1427 used it to make a flat church wall seem to open into real space. Leonardo da Vinci dissected human corpses and drew the heart, the skull and a foetus in the womb with startling precision. Michelangelo's David, unveiled in 1504, stood over five metres tall as a naked citizen-hero. In 1543 the Flemish anatomist Andreas Vesalius, teaching at Padua, published De humani corporis fabrica, correcting errors handed down from the Roman physician Galen by looking inside real bodies.

Behind the masterpieces stood ordinary workshops. Boys of twelve or thirteen were apprenticed to a master, grinding pigments, preparing panels and copying drawings for years before they painted a face; Leonardo himself trained in Andrea del Verrocchio's bottega. A few women broke through: Sofonisba Anguissola of Cremona became a painter at the court of Philip II of Spain. Ordinary Florentines lived among the churches, squares and hospitals the new wealth built, such as the foundling hospital of the Innocenti, opened in 1445.

Did you know? Leonardo planned a treatise on anatomy that was never published, and his anatomical drawings stayed largely unknown for centuries; many are now in the Royal Collection at Windsor.

Historians now stress that the Renaissance was neither sudden nor purely Italian, and that its confidence was the privilege of a wealthy few. Yet its central wager endures. The idea that an individual can be trained, can study nature directly and can shape a life, voiced in Pico della Mirandola's Oration on the Dignity of Man of 1486, runs through every art school, medical faculty and self-help shelf today. The Renaissance made the human figure the measure of the picture, then asked how far that figure could go.

Faith Divided

In 1517 Martin Luther, a friar and professor at the small university of Wittenberg in Saxony, wrote ninety-five theses attacking the sale of indulgences, certificates said to shorten a soul's time in purgatory. He sent them to his archbishop, and printers soon spread them across Germany. Whether he really nailed them to a church door is uncertain; the story first appears after his death. By 1521 he had been excommunicated by Pope Leo X and declared an outlaw at the Diet of Worms. Western Christianity, one Latin Church for a thousand years, was splitting into rival communions: the Reformation.

Luther's central claim was that people are saved by faith alone and that scripture, not the Pope, is the final authority. That put the Bible into ordinary hands. His German New Testament of 1522 sold out fast, and reformers urged parents to teach children to read it. Other movements went further. Huldrych Zwingli reformed Zurich in the 1520s, Jean Calvin made Geneva a model Protestant city from 1541, Anabaptists insisted on adult baptism, and in 1534 Henry VIII made himself head of the Church of England for largely dynastic reasons. Rome answered with its own reform: the Jesuit order, founded in 1540, and the Council of Trent, which met between 1545 and 1563.

The change reached into homes. Protestant clergy could marry, and in 1525 Luther married Katharina von Bora, a former nun who, by tradition, had escaped her convent hidden among herring barrels, and who ran their crowded household, farm and brewery. Convents closed in Protestant lands, removing one of the few respected paths open to unmarried women. In Sweden, the church law of 1686 required clergy to examine every household's reading each year, and these registers let historians watch literacy spread village by village.

It also brought violence. The German Peasants' War of 1524 and 1525, partly inspired by reformers' talk of Christian freedom, ended with perhaps 100,000 dead. France's Wars of Religion included the St Bartholomew's Day massacre of 1572, when thousands of Protestant Huguenots were killed in Paris and other towns. The Thirty Years' War of 1618 to 1648 devastated central Europe; some German regions lost a third or more of their people to fighting, hunger and disease. The Peace of Westphalia that ended it accepted, in effect, that faith was now a matter for each state.

Did you know? Luther's Bible translation did much to shape a common written German, readable by speakers of dialects that had struggled to understand one another.

The split travelled far beyond Europe. Jesuits such as Francis Xavier reached India and Japan in the 1540s, and Catholic missions spread through the Americas and the Philippines, while Protestant refugees carried their churches to the Netherlands, England and North America. The Reformation left a patchwork of churches and a lasting habit: reading a text for yourself and disagreeing with authority in print. Religious toleration, born more of exhaustion than ideals, became a cornerstone of modern liberty. One friar's argument about forgiveness ended by making every reader a potential judge.

The Scientific Method

For most of history, the way to settle a question about nature was to consult an authority: Aristotle on motion, Galen on the body, Ptolemy on the heavens. In the seventeenth century a growing network of European thinkers proposed a different test. A claim should be judged by careful observation, measurement and experiment that anyone could repeat. Francis Bacon set out the programme in his Novum Organum of 1620. This loose set of habits, later called the scientific method, may be the most productive idea our species has had.

It had deep roots. In the early eleventh century the Arab scholar Ibn al-Haytham, working in Cairo, tested theories of vision with darkened rooms and lenses, and insisted that a researcher should doubt even his own conclusions. Medieval scholars at Oxford and Paris argued about experiment too. What changed in the 1600s was scale, instruments and print. Galileo rolled bronze balls down grooved ramps, timing them by weighing water from a flowing vessel, and found that distance grew with the square of time. William Harvey dissected animals and did simple arithmetic: the heart pumped out more blood in half an hour than the whole body contained, so blood must circulate. He published in 1628.

Science also became social. The Royal Society of London, founded in 1660, took the motto Nullius in verba, roughly "take nobody's word for it", and performed experiments before witnesses. Its Philosophical Transactions, launched in 1665, is the oldest science journal still published. Robert Hooke was employed to devise demonstrations for its meetings. In 1687 Isaac Newton's Principia showed that one law of gravitation governed falling apples and orbiting moons, and Edmond Halley used it to predict a comet's return. It reappeared in 1758, after Halley's death, as the calculation required.

The method mattered most when it touched human bodies. In 1747 the Scottish naval surgeon James Lind took twelve sailors with scurvy aboard HMS Salisbury, divided them into six pairs and gave each pair a different remedy. The two given oranges and lemons recovered fastest. It is often called one of the first controlled clinical trials, though the navy took decades to act on it. Every vaccine approval, drug licence and crash test today follows the same logic: compare, measure and let the result overrule the expert.

Did you know? The word scientist was coined only in the 1830s, by the Cambridge scholar William Whewell; Newton thought of himself as a natural philosopher.

The method has never been a single recipe, and scientists still argue about how it really works, from Karl Popper's stress on falsification to modern worries about results that fail to replicate. Its power comes from a humble admission built into the system: anyone can be wrong, including the most famous name in the room. Science is the one human institution designed to find its own mistakes.

Moving the Earth

Look up and the evidence seems obvious: the ground is still and the Sun, Moon and stars wheel around us. For some 1,400 years, astronomers from Baghdad to Oxford used the model set out by Claudius Ptolemy of Alexandria around AD 150, with Earth at the centre and each planet riding small circles, or epicycles, on larger ones. It predicted planetary positions well enough for calendars and horoscopes. Curiously, medieval thinkers did not see the centre as a place of honour: it was the heaviest, lowest spot in creation, farthest from heaven.

In 1543 Nicolaus Copernicus, a canon of Frombork cathedral in Poland, published De revolutionibus orbium coelestium, placing the Sun near the centre and making Earth a planet that spins daily and circles the Sun yearly. He died that same year. The idea was not wholly new: Aristarchus of Samos had proposed a Sun-centred cosmos around 270 BC, and Copernicus's geometry used devices developed by astronomers of the Maragha observatory in Persia, such as Nasir al-Din al-Tusi, though historians debate how they reached him. At first his system was no more accurate than Ptolemy's. Its appeal was its harmony.

Proof came from people, instruments and decades of patient work. The Danish nobleman Tycho Brahe recorded planetary positions with unprecedented accuracy at his island observatory of Uraniborg. His assistant Johannes Kepler used Tycho's records of Mars to show in 1609 that planets move in ellipses, not circles. In 1610 Galileo Galilei turned a telescope on the sky and saw four moons circling Jupiter and, soon after, the full set of phases of Venus, which Ptolemy's arrangement could not produce. Newton's gravitation later explained why it all worked. The direct proof that Earth moves, the tiny annual shift of a nearby star called parallax, was measured by Friedrich Bessel only in 1838.

The cost could be personal. In 1616 Church authorities condemned the Sun-centred view and suspended Copernicus's book until corrected; in 1633 Galileo was tried by the Inquisition, forced to recant and kept under house arrest near Florence until his death in 1642. His eldest daughter, Sister Maria Celeste, a nun, wrote him letters of comfort and practical news, more than a hundred of which survive. Giordano Bruno, burned in Rome in 1600, is often called a martyr to Copernicus, but his trial turned mainly on theological heresies.

Did you know? In 1992 Pope John Paul II formally acknowledged that the Church's condemnation of Galileo had been a mistake, 359 years after his trial.

Copernicus began a long series of demotions. Darwin placed humans within the animal family tree, and Edwin Hubble showed in the 1920s that our galaxy is one among countless others. Each blow was resisted, then absorbed, and each taught the same lesson: appearances can deceive, and careful measurement can overrule common sense. Losing the centre turned out to be the price of understanding where we actually are.

The Age of Reason

In 1762 a Protestant cloth merchant of Toulouse, Jean Calas, was tortured and broken on the wheel for supposedly murdering his son to stop him becoming Catholic. The evidence was flimsy and the verdict driven by prejudice. Voltaire, living near Geneva, took up the case, wrote pamphlets, rallied opinion across Europe, and in 1765 Calas was declared innocent. The episode captures the Enlightenment: a movement of the late seventeenth and eighteenth centuries arguing that reason, evidence and humane principle, rather than tradition, birth or religious authority, should govern how people are treated.

Its thinkers drew courage from the scientific revolution. If Newton could find laws for the heavens, surely society could be studied too. John Locke argued in 1689 that governments exist to protect life, liberty and property, and may be resisted when they fail. Montesquieu's The Spirit of the Laws of 1748 urged that power be divided among separate branches. In Milan, Cesare Beccaria's On Crimes and Punishments of 1764 attacked torture and the death penalty, and rulers from Tuscany to Russia read it. In 1784 Immanuel Kant summed up the mood in two Latin words: Sapere aude, dare to know.

Ideas travelled through a new social world. Diderot and d'Alembert's Encyclopédie, published from 1751 and eventually running to 28 volumes, described crafts and machines as respectfully as theology. Paris salons hosted by women such as Madame Geoffrin brought writers and aristocrats together, while London and Edinburgh had coffee houses and clubs where David Hume and Adam Smith argued. Letters crossed oceans: Benjamin Franklin of Philadelphia corresponded with scientists across Europe, and in Berlin the Jewish philosopher Moses Mendelssohn argued for toleration and became a celebrity. Medicine moved too. Lady Mary Wortley Montagu saw smallpox inoculation practised in Ottoman Istanbul in 1717 and championed it in England.

The Enlightenment had sharp limits, and historians debate them. Many of its champions accepted slavery or profited from it, and most assumed women were unfit for public life. Others turned its logic against them. Olympe de Gouges published a Declaration of the Rights of Woman in 1791 and was guillotined in 1793; Mary Wollstonecraft's A Vindication of the Rights of Woman followed in 1792. The American Declaration of Independence of 1776 proclaimed that all men are created equal; its author, Thomas Jefferson, enslaved more than 600 people over his lifetime.

Did you know? The French government banned the Encyclopédie in 1759, yet volumes kept appearing, quietly protected by Malesherbes, the very official in charge of the book trade.

The Age of Reason gave the modern world much of its vocabulary: rights, toleration, separation of powers, public opinion, a free press. Every constitution that lists the rights of citizens, and every campaign that frees a wrongly convicted prisoner, works in the shadow of the Calas affair. Its unfinished promise is simple to state and hard to keep: the same rules, reasoned in public, for everyone.

Mapping the Globe

In 1490 no map in Europe, Asia or Africa showed the Americas or the full breadth of the Pacific. Within a century, sailors had traced most coastlines of Africa, the Americas and southern Asia, and shown that the world's oceans form one connected body of water. This age of oceanic exploration was driven by trade, faith and rivalry, and it was paid for, overwhelmingly, by the peoples whose shores the voyagers reached.

Long-distance voyaging was not a European invention. Between 1405 and 1433 the Ming admiral Zheng He led seven expeditions of great treasure ships across the Indian Ocean to Arabia and East Africa, returning with envoys and, famously, a giraffe that dazzled the court in Beijing. Polynesian navigators had already settled islands across the vast Pacific, steering by stars, swells and birds. Then Ming China turned inward, and the Atlantic kingdoms pushed out. Bartolomeu Dias rounded the southern tip of Africa in 1488. Christopher Columbus, sailing for Castile, reached the Caribbean in 1492, believing it was Asia. Vasco da Gama, guided across the Arabian Sea by a local pilot from Malindi, reached Calicut in India in 1498.

We know these journeys largely through logs, letters and the record-keepers aboard. Antonio Pigafetta, a young Italian scholar who sailed with Ferdinand Magellan in 1519, kept a diary of the first voyage round the world. It records starvation in the Pacific, when men ate leather and sawdust, and Magellan's death in the Philippines in 1521. Of roughly 240 men who left Spain, 18 returned aboard the Victoria with Juan Sebastián Elcano in 1522. Scurvy probably killed more sailors in this era than storms or battles. Mapmakers worked from such reports, and Gerardus Mercator's projection of 1569 gave navigators straight lines of constant compass bearing.

For the peoples on the far shores, the encounter was often catastrophic: conquest, enslavement and epidemics that emptied whole regions of the Americas. Yet local knowledge filled the European charts. Indigenous guides, African and Arab pilots and Asian merchants supplied routes and names, and in 1769 the Tahitian navigator Tupaia, sailing with James Cook, drew a chart of more than seventy Pacific islands from memory. The Ottoman admiral Piri Reis compiled a world map in 1513 from some twenty sources, including a lost chart by Columbus.

Did you know? Martin Waldseemüller's world map of 1507 is the first known to use the name America, yet he dropped the name from his later maps; by then it had spread too widely to recall.

Every map on your phone descends from those charts, and so does the sense that the planet is one connected place. Global shipping lanes, time zones and satellite navigation all build on a world first measured by small crews at great cost to themselves and to others. The globe became knowable, and the knowing was never neutral.

The Invention of Credit

Credit is far older than banks: Mesopotamian farmers borrowed barley against the coming harvest. What changed in late medieval and early modern Europe was a set of tools that let strangers trust one another across great distances and long spans of time. Its foundations were humble. In 1202 Leonardo of Pisa, known as Fibonacci, published Liber Abaci, teaching European merchants the Hindu-Arabic numerals he had learned from traders in North Africa. Sums that were painful in Roman numerals became quick on paper.

Italian merchants then developed double-entry bookkeeping, recording every transaction twice, as a debit in one account and a credit in another, so that errors showed up whenever the books failed to balance. Genoese city accounts of 1340 already use it, and the friar Luca Pacioli printed the first textbook description in Venice in 1494. We can watch a merchant's life through such records. Francesco Datini of Prato, who died in 1410, left around 150,000 letters and hundreds of account books, tracking wool, wine and spices between Avignon, Barcelona and Florence, along with letters to and from his wife, Margherita.

Banking families such as the Medici used the bill of exchange, a written order to pay a sum in another city and currency, so a wool buyer in Bruges could pay a seller in Florence without shipping coins along bandit-haunted roads. Because the Church forbade usury, profits were often folded into exchange rates. Similar instruments existed elsewhere: Jewish traders whose letters survive in the Cairo Geniza used written orders of payment in the eleventh century, and the Islamic suftaja worked much like a cheque. To lend to the poor, Franciscan friars founded the monti di pietà, charitable pawnshops, from 1462.

The next leap pooled risk. The Dutch East India Company, or VOC, founded in 1602, sold shares to the public: its first subscribers included merchants, craftsmen and even domestic servants, and the shares could be resold on Amsterdam's exchange. The Bank of Amsterdam opened in 1609, and the Bank of England in 1694 lent to a government at war. In Osaka, the Dojima rice market, officially recognised in 1730, became a pioneering market in rice futures. Risk could now be shared, priced and traded, which made long voyages, canals and later factories possible.

Did you know? Isaac Newton lost a large part of his savings in the South Sea Bubble of 1720, when shares in a British trading company soared and then crashed within months.

Credit is the reason a family can buy a home before it has saved the full cost, and why one bank's collapse can shake the world, as it did in 2008. The same machinery has funded hospitals and wars, railways and bubbles. At its heart still sits the medieval merchant's ledger, two columns that must balance, and a written promise that strangers agree to believe.

Tools of Seeing

Around 1286 someone in or near Pisa mounted two glass lenses in a frame and made the first known eyeglasses. A friar preaching in Florence in 1306 spoke of them as an invention less than twenty years old. For scribes, goldsmiths and weavers whose eyes failed in middle age, spectacles added years of close work. They were also the starting point for a revolution: once craftsmen had learned to grind lenses, it was a short step to combining them.

In 1608 the spectacle maker Hans Lipperhey of Middelburg in the Netherlands applied for a patent on a device that made distant things look near. Within a year Galileo Galilei had built his own, eventually magnifying about twenty times, and saw mountains on the Moon, countless stars in the Milky Way and four moons orbiting Jupiter. The telescope undid the old belief that the heavens were perfect and unchanging. Sky-watching instruments were not only European: Ulugh Beg's observatory in Samarkand, built in the 1420s, used a giant meridian arc to measure the year with remarkable accuracy, and in the 1720s and 1730s Jai Singh II built masonry observatories, the Jantar Mantar, at Delhi and Jaipur.

The microscope turned the same trick inwards. Robert Hooke's Micrographia of 1665 showed a flea and a louse in giant detail and named the tiny compartments in cork "cells". In Delft, Antonie van Leeuwenhoek, a cloth merchant with no university training, made single-lens microscopes no bigger than a thumb, magnifying perhaps 270 times. From 1674 he described swarming "animalcules" in pond water and, later, in the plaque from his own teeth: some of the first people to see bacteria saw them in a draper's mouth. It would take two more centuries to link such microbes with disease.

Other instruments measured what no one could see at all. In 1643 Evangelista Torricelli filled a glass tube with mercury, upended it in a dish and found that the column always settled at about 76 centimetres, held up by the weight of the air. In 1648 Blaise Pascal's brother-in-law, Florin Périer, carried a barometer up the Puy de Dôme and watched the column fall with height. Christiaan Huygens's pendulum clock of 1656 cut timekeeping errors from many minutes a day to seconds, and Daniel Fahrenheit's mercury thermometer of 1714 put reliable numbers on heat and fever.

Did you know? Samuel Pepys sat up until two in the morning reading Micrographia and called it "the most ingenious book that ever I read in my life".

New instruments, not just new ideas, built modern science, and they still do: the James Webb Space Telescope, the electron microscope and the weather satellite are distant descendants of a Pisan lens grinder. Each extended the human senses, then forced us to rethink what we thought we knew. Every time we built a better eye, the world turned out bigger, smaller and stranger than anyone had guessed.

The Idea of Progress

For most of recorded history, wise people assumed the best times lay behind them. The Greek poet Hesiod, around 700 BC, described a decline from a golden age to his own wretched age of iron. Hindu traditions place us in the Kali Yuga, the darkest phase of a vast cycle, and Chinese historians wrote of dynasties rising and falling in repeating patterns. The fourteenth-century North African scholar Ibn Khaldun analysed how ruling groups grow strong, then soft, then fall. Change happened, but it went round, or downhill.

The belief that knowledge accumulates and life can steadily improve, the idea of progress, grew slowly in Europe. Bernard of Chartres, in the early twelfth century, is said to have compared scholars to dwarfs perched on the shoulders of giants, seeing further than the ancients only because they stood on them; Isaac Newton borrowed the image in a letter of 1676. Francis Bacon's New Atlantis of 1626 imagined a research institute improving human life through experiment. Late in the seventeenth century a famous literary feud, the Quarrel of the Ancients and the Moderns, asked whether modern writers and scientists could surpass the Greeks and Romans, and Bernard de Fontenelle answered yes in 1688.

The Enlightenment made progress a creed. In 1750 the young Anne-Robert-Jacques Turgot lectured at the Sorbonne on the successive advances of the human mind. Its boldest prophet was the Marquis de Condorcet, a mathematician who predicted the end of slavery, equal rights for women, universal schooling and longer lives. He wrote his Sketch for a Historical Picture of the Progress of the Human Mind while hiding from the Terror, and died in prison in 1794 before it was published. Not everyone agreed. In 1798 Thomas Malthus argued that population would always outrun food, keeping most people poor.

How would anyone know whether life was getting better? That needed numbers, and the habit of collecting them. John Graunt analysed London's weekly bills of mortality in 1662, founding the study of population, and Sweden began national population tables in 1749. Such records, together with skeletons and parish registers, show that before 1800 life expectancy at birth was around 30 almost everywhere, chiefly because so many children died. Today the global average is above 70.

Did you know? The word progress once meant a journey: Elizabeth I's royal "progresses" were her formal summer tours of the kingdom.

Progress is not a law of nature, and the twentieth century, with its world wars and genocides, shook the faith badly. Yet the expectation that children should escape their parents' hardships, that diseases can be beaten and that next year's technology will be better shapes nearly every modern budget, ballot and business plan. The Enlightenment's most radical idea was simply that tomorrow could be better than today, and that people could make it so.

The Age of Machines

For almost all of history the power available to a person was the power of a body: muscles, a few animals, a mill wheel, the wind. From about 1760, in a damp corner of northern England, that ceiling began to lift. A run of inventions mechanised the spinning of cotton: James Hargreaves's spinning jenny around 1764, Richard Arkwright's water frame, patented in 1769, and Samuel Crompton's mule in 1779. Arkwright then did something genuinely new. In 1771 at Cromford in Derbyshire he put his machines in a tall mill beside a stream, drove them from a single waterwheel and hired people to tend them by the clock. The factory was born, and with it the idea that work happens at a set place, at set hours, at the pace of a machine.

Output per worker leapt. A hand spinner drew one thread at a time; a mule spinner soon minded hundreds of spindles, and cotton cloth went from a luxury to something cheap enough to clothe the poor. We know how it felt because the age wrote itself down. The Sadler Committee of 1832 heard mill hands describe shifts of fourteen hours and more, factory inspectors filed reports after 1833, and workers left memoirs of fines, beatings and the factory bell. Children were prized because they were cheap and nimble; the Factory Act of 1833 barred under-nines from textile mills and capped the hours of older ones.

Bodies kept the accounts too. Army recruitment records show that the average height of British men born in the decades around 1830 to 1850 stalled or fell, even as the national income rose. Historians debate the causes, from crowded housing and disease to dearer food, but it is a sharp reminder that a richer country is not automatically a healthier one.

The model travelled fast. In 1790 Samuel Slater, a former apprentice in an English mill, rebuilt Arkwright's machinery from memory at Pawtucket, Rhode Island. At Lowell, Massachusetts, thousands of young women from New England farms lived in company boarding houses and walked out in protest in 1834 and 1836. Bombay's first cotton-mill company was founded in 1854 by Cowasjee Nanabhoy Davar, and in 1872 Japan's government opened the Tomioka silk mill, where young women learned French-designed machinery and carried the skills home to their villages.

Did you know? The Luddites who smashed machines from 1811 took their name from Ned Ludd, a probably mythical apprentice said to have broken two knitting frames in a fit of rage.

The factory set the template for modern life: the commute, the weekly wage, the clocked-in shift, the cheap shirt. Its descendants still run on the same logic, from the garment workshops of Dhaka to the warehouses that pack online orders overnight. We still live by the factory's hours, even those of us who have never set foot in one.

Power on Demand

A waterwheel works only where water falls, and only when the river is not frozen or dry. The steam engine broke that tie. Thomas Newcomen's engine of 1712, installed at a coal mine near Dudley in the English Midlands, used steam and the weight of the air to work a pump, lifting water out of mines so that miners could dig deeper. It was a huge, hungry machine, but it worked, and dozens were soon nodding over pits across Britain and Europe.

The leap came from a Scottish instrument maker. Repairing a model Newcomen engine at the University of Glasgow in the 1760s, James Watt realised that heating and cooling the same cylinder wasted most of the fuel. His answer, patented in 1769, was a separate condenser that kept the cylinder hot. With the Birmingham manufacturer Matthew Boulton he built engines that burned far less coal, and from 1781 his sun-and-planet gear turned the rocking beam into rotary motion that could drive a mill. Power could now be made wherever coal could be carted: in the middle of Manchester, at a brewery in London, or in a sugar mill in the Caribbean.

The cost fell on people underground. Coal output soared, and with it the number of miners. In 1842 a parliamentary commission took evidence from Patience Kershaw, aged seventeen, who hauled coal tubs through narrow seams near Halifax and told the inquiry that the men she worked for sometimes beat her if she was slow. The Mines Act that year barred women, girls and boys under ten from working below ground. Surviving engines are evidence too: the Smethwick Engine of 1779, still working in a Birmingham museum, shows the brute scale of the machines.

Steam then left the factory. Richard Trevithick's high-pressure engine pulled a train of iron at Penydarren in Wales in 1804, steamships crossed oceans, and in 1853 the American steam warships that the Japanese called the black ships sailed into Edo Bay and helped force Japan open to the wider world. By 1913 Britain alone was digging nearly 290 million tonnes of coal a year.

Did you know? Watt invented the horsepower as a sales tool, rating his engines against the horses that brewers and mill owners would be replacing; the watt, the unit on every light bulb, is named after him.

Steam set humanity on a fossil-fuelled path that still shapes daily life. Air bubbles trapped in Antarctic ice show carbon dioxide at around 280 parts per million before industrialisation; today it is above 420. Almost every power station, ship and factory since descends from the idea Watt sold to his customers: power on demand, as long as you keep feeding the fire.

Rise of the City

In 1851 the British census recorded something no large country had seen before: more people living in towns than in the countryside. Factories needed hands, and millions came, from the farms of Lancashire and Yorkshire, from famine-struck Ireland, from the Scottish Highlands. Manchester, Leeds, Glasgow and Birmingham swelled faster than anyone could build for them. Builders threw up back-to-back houses in rows that shared a rear wall, with one room on each floor, no through-draught and a single court outside where dozens of families shared a pump and a few privies.

We know these places in unusual detail because reformers counted them. In his Report on the Sanitary Condition of the Labouring Population of 1842, Edwin Chadwick found that in Liverpool the average age at death was 35 for gentry, 22 for tradesmen and 15 for labourers and their families, figures dragged down by the deaths of infants. Friedrich Engels walked the courts of Manchester and described Little Ireland, by the River Medlock, in The Condition of the Working Class in England in 1845. In Birmingham one court of back-to-backs survives, restored by the National Trust, with its washhouse and its shared privies.

City life reshaped bodies. Cholera reached Britain in 1832 and returned in 1848 and 1853. Children growing up under coal smoke and in dark courts developed rickets, the bowed legs of a disease caused by too little sunlight on the skin. Yet cities also offered wages, company, newspapers, music halls and the chance to escape a landlord's or a father's control, and people kept coming.

The pattern repeated around the world. Chicago grew from about 30,000 people in 1850 to over a million by 1890. Osaka's cotton mills earned it the nickname "the Manchester of the East", and in Bombay mill workers crowded into chawls, tenement blocks with shared taps and toilets along each landing. Over time, cities forced the invention of things we now take for granted: sewers, clean piped water, building codes, public parks, the police and, with Saturday half-holidays won by mill workers from the 1850s, the beginnings of the weekend.

Did you know? London's sewer network, built by Joseph Bazalgette after the hot summer of 1858 known as the Great Stink, still carries much of the city's waste today.

Since around 2007 more than half of humanity has lived in towns and cities, and the growth now is fastest in places like Lagos, Dhaka and Kinshasa. The questions Chadwick asked about water, drains and crowding are being asked again in informal settlements across the world. The city is humanity's most successful habitat, and it has always been paid for in pipes.

Annihilating Distance

On 15 September 1830 the Liverpool and Manchester Railway opened, the first line built to carry passengers and goods between two cities by steam alone. It had a grim start: the MP William Huskisson stepped onto the track and was struck by Stephenson's Rocket, becoming one of the first widely reported railway deaths. Within twenty years Britain had more than 6,000 miles of track, and journeys that had taken days by stagecoach took hours.

Wires followed the rails. William Cooke and Charles Wheatstone patented an electric telegraph in 1837, and railway companies strung it beside their lines to signal trains. Its power became famous on 1 January 1845, when John Tawell, wanted for murder, fled Slough by train; a telegraph message reached Paddington before he did, and police tracked him from the platform. In America, Samuel Morse sent "What hath God wrought" from Washington to Baltimore in 1844. For the first time in history, information could outrun any horse, ship or train.

The railway changed what people ate, where they lived and how they saw time. Fresh milk, fish and vegetables reached city markets overnight. Thomas Cook ran his first excursion in 1841, taking hundreds of temperance supporters from Leicester to Loughborough, and seaside resorts grew around the stations. Every town had kept its own local time; railways needed one timetable, and by 1848 most British lines ran on London time. The United States and Canada adopted railway time zones in 1883.

The network stretched across oceans and continents. In 1866 the giant steamship Great Eastern laid a lasting telegraph cable from Valentia in Ireland to Heart's Content in Newfoundland, after an 1858 cable had failed within weeks. On 10 May 1869 the Pacific Railroad was completed at Promontory Summit, Utah, built in large part by thousands of Chinese labourers who blasted tunnels through the Sierra Nevada. India's first passenger train ran from Bombay to Thane in 1853, and from 1870 a direct cable carried messages between Britain and India in hours instead of weeks.

Did you know? The clock on Bristol's Corn Exchange still has two minute hands, one for local time and one for London time, because Bristol ran about ten minutes behind the capital.

Speed brought new kinds of power. Governments could move troops and orders quickly, newspapers carried yesterday's prices from distant markets, and merchants in Calcutta and London traded on shared news. Every message app, video call and same-day delivery descends from that collapse of distance. The world has felt small ever since the wires went up.

Capital and Labour

Industrial capitalism produced wealth on a scale no society had seen, and it produced it unevenly. Owners who put money into mills, mines and railways could become fabulously rich. The people who worked the machines often did not, at least at first. Economic historians such as Robert Allen describe an "Engels' pause" in Britain, from roughly 1790 to 1840, when output per worker climbed while real wages barely moved. Others question how long it lasted, but the sense of a widening gap was real, and it gave rise to a question that has never gone away: who owns the gains?

The evidence sits in wage books, price lists, trial records and the words of the people involved. In 1834 six farm labourers from Tolpuddle in Dorset were sentenced to transportation to Australia for swearing a secret oath to their new union. In 1838 the Chartists published a People's Charter demanding the vote for all men, and millions signed their petitions. In July 1888 the women and girls at the Bryant and May match factory in east London walked out over fines, low pay and "phossy jaw", a bone-rotting disease caused by white phosphorus, and won.

The conflict was global. In Chicago a bomb at a labour rally in Haymarket Square in May 1886 led to the execution of four anarchists after a much-disputed trial, and the event is remembered each year on May Day. At Homestead, Pennsylvania, in 1892 Andrew Carnegie's managers brought in armed guards against striking steelworkers, and people died on both sides. In Mexico, copper miners at Cananea struck in 1906, and the 1917 Constitution wrote the eight-hour day into law.

Ideas competed as fiercely as people. Adam Smith had argued in 1776 that the division of labour made nations rich. Robert Owen ran the New Lanark mills in Scotland as a model community with schools for workers' children. Karl Marx and Friedrich Engels published the Communist Manifesto in 1848, predicting that capitalism would dig its own grave. Governments, meanwhile, became referees: Britain's Factory Acts, Bismarck's sickness insurance law of 1883 in Germany and the International Labour Organization's eight-hour convention of 1919.

Did you know? The Tolpuddle Martyrs were punished not for striking but for swearing an oath; public protest won them pardons in 1836, and most later emigrated to Canada.

The settlements struck in those decades still shape working life: unions, the weekend, sick pay, pensions, minimum wages and limits on hours. So does the argument. Debates about executive pay, gig work and automation are the same quarrel in new clothes. Every pay slip carries a little of the bargain struck between capital and labour.

The Germ Revolution

For most of history, people blamed disease on bad air, imbalanced humours, sin or bad luck. In the middle of the nineteenth century a handful of doctors and scientists began to prove something stranger: that many diseases were caused by living things too small to see. The germ theory of disease did not arrive in a single flash. It was pieced together from hospital wards, city maps and laboratory flasks, and it went on to cut death rates more than any other idea in history.

The first clues came from counting the dead. In 1847 Ignaz Semmelweis, working in a Vienna maternity hospital, noticed that women delivered by doctors, who came straight from dissecting corpses, died of childbed fever far more often than those delivered by midwives. When he made staff wash their hands in chlorinated lime, deaths fell sharply. In London in 1854, John Snow plotted cholera deaths around Soho and traced them to a single water pump on Broad Street. Neither man could see the cause, but both showed that disease travelled on hands and in water.

Then came the microscope. In the early 1860s Louis Pasteur boiled broth in swan-necked flasks and showed that it stayed fresh unless microbes from the air could reach it: life came only from life. In Glasgow Joseph Lister applied the lesson to surgery, treating the open fracture of an eleven-year-old boy, James Greenlees, with carbolic acid in 1865; the wound healed without infection. In 1882 Robert Koch identified the bacterium that causes tuberculosis, then the leading killer in Europe, and in 1884 he described the cholera germ after studying outbreaks in Egypt and Calcutta.

The practical results reached everyone. Cities built sewers and filtered their water, and Jersey City began chlorinating its supply in 1908. Pasteur's rabies vaccine saved a bitten boy, Joseph Meister, in 1885, and vaccines for diphtheria, tetanus and later polio and measles followed. Around 1800 roughly four in ten children worldwide died before their fifth birthday; today it is about four in a hundred. Global life expectancy at birth rose from about 32 in 1900 to about 73 today.

Did you know? The famous removal of the Broad Street pump handle on 8 September 1854 came after the outbreak was already in decline; Snow's real achievement was the evidence, which took years to win over the authorities.

The germ revolution is why most parents now expect every child to grow up, and why handwashing, clean water and vaccination are the cheapest life-savers we have. The COVID-19 pandemic was a sharp reminder that the microbes have not gone away. Soap, sewers and vaccines have saved more lives than any surgeon's knife.

The Assembly Line

Before 1913 a car was built like a house. A team of skilled workers gathered around a stationary chassis and fitted parts as they were brought to them, and building one chassis took around twelve and a half hours. At the Ford Motor Company's Highland Park plant in Michigan, engineers tried something different. In April 1913 they set flywheel magnetos moving past a row of workers, each of whom did one small job. Assembly time fell dramatically. By the end of the year the whole chassis was being pulled along by a rope, and by early 1914 the time had dropped to about an hour and a half.

The assembly line combined older ideas: interchangeable parts from American armouries, continuous flow from flour mills, and the overhead trolleys of Chicago's meatpacking houses. Ford's insight was to make the work move while the worker stayed still. The job was broken into dozens of short, repeated steps that a newcomer could learn in a day. Ford's own time studies, company photographs and the memoirs of those who worked there record the result: soaring output, and a boredom so intense that many workers quit within weeks.

Ford's answer, in January 1914, was the "five-dollar day", which roughly doubled typical pay for qualifying workers. It came with strings: inspectors from the company's Sociological Department visited homes to check that men lived soberly and thriftily. Many of the workers were recent immigrants from Poland, Italy, Hungary and the Middle East, and the company ran English classes to turn them into model Americans. The pay worked, and the Model T became something its own builders could afford. More than fifteen million were made between 1908 and 1927.

The method spread almost everywhere. André Citroën opened a mass-production car plant in Paris in 1919. The Soviet Union built a giant car factory at Nizhny Novgorod with Ford's help in the early 1930s. The Italian thinker Antonio Gramsci, writing in a Fascist prison, popularised the term Fordism for the new world of mass production and mass consumption. Charlie Chaplin mocked it in Modern Times in 1936, his tramp swept into the gears. After the Second World War, Taiichi Ohno and colleagues at Toyota refined the idea into lean production, which spread to factories worldwide.

Did you know? Ford wrote that the idea came partly from Chicago's meatpackers, whose overhead trolleys carried carcasses past workers who each made one cut: a disassembly line.

Almost everything you own, from a phone to a pair of trainers, was made on a descendant of Ford's line, often in Shenzhen, Ho Chi Minh City or Dhaka. It made goods cheap and work repetitive, and both are still with us. Split the job finely enough, and the people who build the car can buy one.

Harnessing Electricity

In 1831 Michael Faraday moved a magnet through a coil of wire at the Royal Institution in London and made a current flow. That principle, electromagnetic induction, sits inside almost every power station on Earth. It took half a century to turn it into a public service. In 1881 the small Surrey town of Godalming lit its streets and some homes from a waterwheel-driven generator, and in September 1882 Thomas Edison's Pearl Street station began supplying a few dozen customers in lower Manhattan. Edison in America and Joseph Swan in England had each developed a practical incandescent light bulb, and the two later merged their British businesses.

The question was how to send power over distance. Edison favoured direct current; George Westinghouse, using Nikola Tesla's patents, backed alternating current, which transformers could step up for long-distance lines and step down for homes. Alternating current won. In 1896 power from the Niagara Falls generating station reached Buffalo, more than twenty miles away, and national grids followed in the 1920s and 1930s. In 1920 Lenin declared that "communism is Soviet power plus the electrification of the whole country", and launched a state plan to build it.

Electricity changed bodies and days as much as industries. Bright, safe light stretched evenings and shift work into the night, and over the following century people went to bed later. Factories replaced a single steam engine driving belts and shafts with a small electric motor on each machine, which let engineers rearrange whole floors, though productivity took decades to catch up. Electric trams carried workers out to new suburbs. In homes, irons, vacuum cleaners, washing machines and refrigerators arrived from the 1920s, and radio brought news and music into the kitchen.

The benefits spread unevenly. Under one in ten American homes had electricity in 1907; by 1930 about two in three did, but most farms still did not, so in 1936 Congress created loans for rural electric cooperatives. Historians such as Ruth Schwartz Cowan have argued that appliances did not shrink housework as much as advertisers promised, because standards of cleanliness rose to match.

Did you know? Godalming's pioneering public supply of 1881 was powered by a waterwheel on the River Wey, and the town went back to gas lamps within a few years when the scheme failed to pay.

Today around 700 million people, most of them in sub-Saharan Africa, still live without reliable electricity, and the fight to supply them cleanly is one of the central problems of the century. For everyone else it is invisible, flowing into phones, fridges, hospital ventilators and data centres. Electricity is the power you never see, until the moment it stops.

Billions of Us

For most of our species' existence, human numbers grew so slowly that the change was barely visible across a lifetime. Then the curve bent upwards. The world reached about one billion people around 1804, two billion in 1927, three billion in 1960, and on 15 November 2022 the United Nations marked the arrival of the eight-billionth. No mammal of our size has ever been so numerous.

We know this from counting. Sweden has kept national population statistics since 1749, the longest unbroken series in the world, and censuses spread through the nineteenth century, from Britain's first in 1801 to India's in 1872. Earlier figures are reconstructed from parish registers, tax rolls and the patient work of demographers. Together they show a pattern called the demographic transition. First death rates fall, thanks to steadier food, clean water and vaccines, while families still have many children, so numbers rise fast. A generation or two later, birth rates fall too, and growth slows.

Food made the surge possible. In 1798 Thomas Malthus warned that population would always outrun the harvest. He was not wrong about the past, but he missed what was coming. In 1909 Fritz Haber found a way to pull nitrogen from the air, and from 1913 Carl Bosch scaled it up at a BASF plant in Germany to make fertiliser. The scientist Vaclav Smil estimates that around 40 percent of people alive today owe their food to that process. In the 1960s Norman Borlaug's high-yield wheat and new rice varieties drove a Green Revolution in Mexico, India and Pakistan, and India's wheat harvest more than doubled within about seven years.

The human experience of family changed with the numbers. In 1950 a woman had about five children on average; today the global figure is about 2.3. South Korea's rate fell to about 0.72 in 2023, the lowest in the world, while Niger's remains above six. Japan's population has been shrinking since around 2010, and by the end of this century Nigeria may be home to more people than Europe's largest countries combined.

Did you know? Demographers estimate that about 117 billion people have ever been born, so roughly one in fifteen of all the humans who have ever lived is alive today.

Global growth peaked at over two percent a year in the late 1960s and is now below one percent, and the UN expects numbers to level off later this century. The challenges ahead are ageing societies, migration and feeding everyone without wrecking the soil and climate that feed us. Deaths fell first and births followed later; the gap between them made billions.

The Great Divergence

In 1750 the world's great workshops were in Asia. By the economic historian Paul Bairoch's estimates, China and India together produced more than half of all the world's manufactured goods, from porcelain and silk to the fine cotton muslins of Bengal. Britain made about two percent. By 1900 the picture had flipped: Britain and the United States made over forty percent between them, India under two. Historians call this split the Great Divergence, and its causes are among the most argued-over questions in the subject.

The comparison has been sharpened by evidence from ordinary lives. Researchers compare wages against the price of a basket of food, fuel and cloth in London, Beijing, Delhi and Amsterdam, and measure heights from army records and skeletons. In his book The Great Divergence in 2000, Kenneth Pomeranz argued that the richest parts of China, such as the Yangzi Delta, were broadly comparable with England as late as the mid-eighteenth century. Others, including Robert Allen, point to Britain's unusual mix of high wages and cheap coal, which made it worth inventing labour-saving machines. Institutions, science, colonies and slavery-grown cotton all enter the argument.

What is not in doubt is what happened to people. Machine-made Lancashire cloth, protected by tariffs at home and pushed into Indian markets, helped ruin many of Bengal's hand weavers. China lost the Opium Wars of 1839–42 and 1856–60 to steam-powered British warships. According to the UN's Human Development Report of 1999, the income gap between the richest and poorest countries widened from about three to one in 1820 to about 35 to one in 1950 and about 72 to one in 1992. Even height followed money: Dutch men, once relatively short by European standards, are now among the tallest people on Earth.

Divergence was not destiny. Meiji Japan from 1868 deliberately imported railways, silk mills and schools and became an industrial power within two generations. South Korea and Taiwan followed from the 1960s, and China's reforms from 1978 lifted hundreds of millions of people out of extreme poverty. Around 1820 most of humanity lived in what we would now call extreme poverty; today fewer than one in ten people do, and China once again makes more goods than any other nation.

Did you know? By Bairoch's estimates, India's share of world manufacturing fell from about 25 percent in 1750 to under 2 percent by 1900.

Yet a child born today in Japan can expect to live around thirty years longer than one born in Chad or Nigeria. The gap opened by industrialisation is narrowing, slowly and unevenly. In two centuries the workshop of the world moved from Asia to the Atlantic, and it is moving back.

A Nation by Consent

On 4 July 1776, delegates in Philadelphia approved a document that rested a new state on a claim no country had been founded on before: that governments derive "their just powers from the consent of the governed". The Declaration of Independence, drafted mostly by Thomas Jefferson, a 33-year-old Virginian, turned a quarrel over taxes into an argument about where power comes from. Not from a crown, nor from a family chosen by God, it said, but from the people who must obey.

The trouble was the word people. We can measure who was left out, because the new republic counted itself. The first federal census, in 1790, found about 3.9 million inhabitants, of whom nearly 700,000 were enslaved. Jefferson himself enslaved more than 600 people over his lifetime. Women could not vote, except, briefly and through loose wording, property-owning women in New Jersey between 1776 and 1807. Native nations, from the Haudenosaunee to the Cherokee, were treated as obstacles to western land rather than as part of the governed.

Yet the words escaped their authors. In March 1776 Abigail Adams wrote to her husband John asking Congress to "remember the ladies"; he teased her in reply, and both letters survive. In 1781 an enslaved woman in Massachusetts, Elizabeth Freeman, known as Mum Bett, heard the new state constitution declare that all men are born free and equal. She found a lawyer, sued, and won her freedom; court cases like hers ended slavery in Massachusetts during the 1780s. A promise written down can be quoted back at the powerful by the very people it forgot.

The revolution also scattered families across oceans. Tens of thousands of Loyalists fled to Canada, Britain and the Caribbean. Thousands of Black Americans who had escaped to the British side on a promise of freedom were shipped to Nova Scotia, and in 1792 nearly 1,200 of them sailed on to West Africa to help found Freetown in Sierra Leone. For them, consent of the governed meant leaving the governed altogether.

Did you know? The Declaration was not signed on 4 July: most delegates signed the handwritten parchment copy on 2 August 1776, and a few signed later still.

The Constitution of 1787 and the Bill of Rights of 1791 built the claim into machinery: elections, written limits on power, freedom of speech and worship. The same Constitution counted each enslaved person as three-fifths of a person when sharing out seats in Congress. Every widening of American citizenship since, from the 14th Amendment of 1868 to the Voting Rights Act of 1965, has been argued as finally keeping the promise of 1776, and most of the world's constitutions now open with some version of "we the people". The phrase was half true when it was written, and it has been a to-do list ever since.

Liberty, Equality

In the spring of 1789, before anyone stormed anything, the people of France were asked what was wrong. Every parish, town and guild drew up a cahier de doléances, a notebook of grievances, for the Estates-General that Louis XVI had summoned to fix his bankrupt treasury. Tens of thousands were written, and historians read the survivors as the nearest thing to an opinion poll of an eighteenth-century nation: villagers complaining of the salt tax, of tithes, of the lord's right to hunt across their fields and to keep pigeons that ate their seed.

What followed moved fast. On 14 July Parisians took the Bastille, a fortress-prison then holding just seven inmates. On 26 August the National Assembly passed the Declaration of the Rights of Man and of the Citizen: "Men are born and remain free and equal in rights." In October thousands of market women, angry at the cost of bread, marched to Versailles in the rain and brought the royal family back to Paris. Feudal dues were swept away, Jews gained full citizenship in 1791, divorce became legal in 1792, and in 1794 the Convention abolished slavery in the colonies, after enslaved people in Saint-Domingue had risen and freed themselves.

The playwright Olympe de Gouges noticed who was missing. Her Declaration of the Rights of Woman and of the Female Citizen of 1791 argued that if a woman had the right to mount the scaffold, she must also have the right to mount the speaker's platform. In November 1793 she was guillotined. By then France was at war with much of Europe and with rebels at home, and the Revolution had turned on itself. Louis XVI was executed in January 1793; during the Terror of 1793 and 1794 around 17,000 people were officially executed, and many more died in prisons or in the crushing of the Vendée revolt. Robespierre, who had once argued against the death penalty, went to the guillotine himself in July 1794.

Did you know? The political words "left" and "right" date from 1789, when supporters of the king sat to the right of the Assembly's president and his opponents to the left.

For ordinary people the Revolution reached into the most private corners of life. It renamed the months, imposed a ten-day week that workers disliked because it gave them one rest day in ten instead of one in seven, and replaced hundreds of local weights and measures with the metric system. Napoleon restored slavery in 1802, crowned himself emperor, and carried the new civil code across Europe, from Italy to Poland.

The world took away a double lesson. Rights could be declared for everyone at once, in plain words, by a people rather than a king. And a revolution that claims to speak for the whole people can decide that anyone who disagrees is not part of it. Every revolution since has had to choose which half of 1789 to follow.

The End of Slavery

For most of recorded history, slavery was part of the furniture of the world: in Rome, in Abbasid Baghdad, in West African kingdoms, in the Aztec capital. What made the Atlantic system different was its scale and its tie to skin colour. Between the early 1500s and the 1860s, around 12.5 million Africans were forced aboard European and American ships, and about 10.7 million survived the crossing. We know these figures with rare precision because the Trans-Atlantic Slave Trade Database has pieced together some 36,000 voyages from ship logs, insurance papers and port registers.

The movement to end it began with the enslaved themselves. In August 1791 enslaved people in the French colony of Saint-Domingue rose up; under leaders such as Toussaint Louverture they fought off French, Spanish and British armies, and in 1804 founded Haiti, the first state born of a successful slave revolt. In Jamaica at Christmas 1831 the Baptist deacon Sam Sharpe called a strike that became a rebellion of tens of thousands; he was hanged in 1832, and the shock pushed Parliament in London to act. Bodies bear witness too. Skeletons excavated at the African Burial Ground in New York, rediscovered in 1991, show spines and muscle attachments scarred by crushing labour.

Words did the rest. In 1789 Olaudah Equiano published his Interesting Narrative, a bestseller describing his kidnapping as a boy in what is now Nigeria, although historians debate where he was born. The campaigner Thomas Clarkson gathered evidence from sailors in Bristol and Liverpool, and the print of the slave ship Brookes, with people packed like cargo, became one of the first mass-produced protest images. Thousands of British families boycotted slave-grown sugar, and in 1824 the Leicester Quaker Elizabeth Heyrick demanded "immediate, not gradual" emancipation, years before the male leaders dared.

Did you know? Brazil was the last country in the Americas to abolish slavery, with the Golden Law of 13 May 1888, signed by Princess Isabel while her father, the emperor, was abroad.

Laws came slowly and at terrible cost. Britain banned its slave trade in 1807 and slavery in most of its colonies from 1834, paying compensation to the owners and nothing to the enslaved. The United States needed a civil war that killed at least 620,000 soldiers before the 13th Amendment of 1865. Russia freed its serfs in 1861. Mauritania was the last country to abolish slavery formally, in 1981.

Freedom on paper did not end the story. Freedpeople in the American South faced sharecropping debt and decades of terror, and in Jamaica the best land stayed with the planters. In the 1930s interviewers recorded more than 2,300 elderly Americans who had been born enslaved, and their voices are still kept at the Library of Congress. Today the International Labour Organization estimates that around 50 million people live in forced labour or forced marriage. Abolition was one of humanity's greatest moral victories, and it is not finished.

Government by Vote

For most of history, who ruled was settled by birth, by force or by a small circle of the rich. The idea that ordinary people should regularly choose their rulers spread in the nineteenth century, and it spread unevenly, one widening at a time. In Britain before 1832, Old Sarum, a grassy hill in Wiltshire with a handful of voters, sent two members to Parliament, while booming Manchester sent none. The Great Reform Act of 1832 tidied this up, yet afterwards only around one adult man in five in England and Wales could vote.

Ordinary people paid for each step. In August 1819 a crowd of perhaps 60,000 gathered at St Peter's Field in Manchester to demand reform; cavalry charged with sabres, and at least fifteen people died in what the press called Peterloo. The Chartists of the 1830s and 1840s demanded votes for all men, secret ballots and pay for MPs, and carried petitions with millions of signatures to Westminster. Five of their six demands eventually became law; only annual Parliaments never did.

Voting itself used to be a public act. Before the secret ballot, an elector climbed onto the hustings and called out his choice in front of his landlord, his employer and the crowd. Printed poll books recorded who voted for whom, and historians use them today to show how tenants voted with their landlords. The colony of Victoria in Australia introduced the government-printed secret ballot in 1856, Britain followed in 1872, and the "Australian ballot" spread across the United States in the 1890s. A pencil behind a curtain did more for independence of mind than many speeches.

Did you know? In Indian elections a line of indelible ink is painted on each voter's left forefinger to stop anyone voting twice, a practice used since 1962.

The largest leap came after empire. India held its first general election in 1951 and 1952 with every adult entitled to vote from day one, at a time when most of the roughly 173 million eligible voters could not read. Each party was given a picture symbol, such as a pair of bullocks or an oil lamp, so that anyone could choose, and polling took months to stage across mountains, deserts and forests. In the United States, by contrast, the 15th Amendment of 1870 promised Black men the vote, a promise broken across much of the South until 1965.

Most countries now hold elections of some kind, though many are neither free nor fair. India's 2024 election, with nearly a billion registered voters, was the largest act of collective choice ever held. The ballot did not make people wise or equal. What it did was turn subjects into citizens who could remove their rulers without a sword.

The Nation-State

Ask a farmer in 1800 what he was and he might have said Catholic, or a man of his valley, or the tenant of a particular lord. A century later his great-grandchildren were far more likely to answer French, German, Italian or Japanese. The nation-state, a country whose borders are meant to match a people sharing a language, a history and a sense of belonging, is a recent invention that now feels as natural as weather.

It had to be built, often in classrooms. When the French government surveyed its schools in 1863, it found that about one person in five spoke no French at all, only Breton, Occitan, Basque, Alsatian or another tongue. Jules Ferry's laws of 1881 and 1882 made primary school free, compulsory and French; Breton children caught speaking their own language could be made to wear a token of shame. Italy, unified in 1861, was home to people who mostly spoke regional languages, and historians estimate that only a small minority used standard Italian. Japan after 1868 took the same road at speed, with compulsory schools from 1872, a conscript army and a standard speech based on Tokyo.

Nations were also made of paper and song. Censuses sorted people by mother tongue, maps coloured each country a single shade, and newspapers let a reader in Turin imagine thousands of strangers reading the same news at breakfast. The political scientist Benedict Anderson called nations imagined communities, because their members will never meet most of their compatriots yet feel bound to them. Anthems, flags, national museums and folk-tale collections, such as the stories the Brothers Grimm began publishing in 1812, gave the new identity a past.

Did you know? Passports were rarely needed for travel within Europe before the First World War; the modern passport booklet was standardised at a League of Nations conference in 1920.

The glue could be generous. It paid for schools, pensions and railways for people who now counted as "us", and it inspired colonised peoples from Ireland to Vietnam to demand states of their own. It could also poison. If a nation is one people, minorities become a problem to be solved. Conscript armies of millions marched in 1914 believing they defended the homeland. In 1915 the Ottoman government's deportations killed hundreds of thousands of Armenians, around a million by most estimates. After 1918, the principle of self-determination redrew Europe's borders and left millions on the wrong side of them.

Today almost all the world's land belongs to one of around 195 states, and almost everyone carries a nationality on paper. It decides where you may live, work and travel, which team you cheer and which history you learn at school. The nation is an idea that people agreed to share, which is exactly why it is so powerful, and so easy to turn against a neighbour.

The Labour Movement

On 21 April 1856 stonemasons building the University of Melbourne put down their tools and marched to Parliament House. Their demand fitted on a banner: eight hours' work, eight hours' rest, eight hours' recreation. They won, and became among the first organised workers anywhere to secure the eight-hour day. The date was celebrated with processions for decades, and the slogan travelled round the world.

Industrial work had stretched the day to its limits. Factory inquiries in Britain, the United States and Germany recorded shifts of twelve and fourteen hours, six days a week, with children at the looms. The body kept the score: doctors noted the bent spines of mill hands, miners' lungs blackened by coal dust, and the "phossy jaw" that rotted the faces of match workers poisoned by white phosphorus. Organising was risky, because in many countries a union could be prosecuted as a conspiracy. Workers formed friendly societies, unions and co-operatives anyway, pooling small sums to see each other through sickness, strikes and funerals.

The most powerful arguments were often disasters. On 25 March 1911 fire broke out on the eighth floor of the Asch Building in New York, home of the Triangle Shirtwaist Factory. A door on the ninth floor was locked, the single fire escape collapsed, and the fire brigade's ladders reached only to the sixth floor. Within about eighteen minutes 146 workers died, most of them young Jewish and Italian immigrant women; dozens jumped to the pavement. Frances Perkins watched from the street. She later dated the New Deal from that day, and as the first woman in a US cabinet she helped pass the 1938 law that set the forty-hour week.

Did you know? May Day, the international workers' holiday, commemorates a strike for the eight-hour day that began in Chicago on 1 May 1886.

Gains spread through laws, treaties and sheer persistence. In 1919 the new International Labour Organization adopted its first convention, limiting industrial work to eight hours a day and 48 a week. Henry Ford moved his factories to a five-day week in 1926, helping make the two-day weekend normal. In Gdańsk in August 1980, a strike at the Lenin Shipyard, sparked by the sacking of the crane operator Anna Walentynowicz, grew into Solidarity, a union of around ten million Poles that helped bring down communist rule.

The story is not finished. In April 2013 the Rana Plaza building near Dhaka, in Bangladesh, collapsed onto five garment factories, killing more than 1,100 people who had been sent back inside despite cracks in the walls. It led to a binding safety accord signed by many of the world's clothing brands. The weekend, the paid holiday and the fire exit at work were not gifts from the economy. They were won by people who organised.