The Third Chimpanzee: The Evolution and Future of the Human Animal

by Jared Diamond

  Alternative Models of Human Society

  The range and diversity of cultural practices in New Guinea is greater than that of same-size areas elsewhere in the modern world, because isolated tribes were able to live out social experiments that others would find unacceptable. Forms of self-mutilation and cannibalism, for example, varied from tribe to tribe. Child-rearing practices ranged from extreme permissiveness, through punishment of misbehavior by rubbing a child’s face with stinging nettles, to repression so strict that it led to child suicides.

  Among one group, the Barua, men lived with young boys in a single large house, while each man had a separate house for his wife, daughters, and infant sons. The Tudawhes, in contrast, had two-story houses in which women, babies, unmarried girls, and pigs lived on the lower level, while men and unmarried boys lived on the upper level that they entered by a separate exterior ladder.

  If the loss of cultural diversity in the modern world meant only the end of self-mutilation and child suicide, we wouldn’t mourn it. But the societies whose cultural practices now dominate the globe owe that domination to their economic and military success. These qualities aren’t necessarily the ones that encourage happiness or promote long-term human survival.

  Our consumerism and environmental exploitation may serve us well now, but they are not good signs for our future. Features of American society that already rate as disasters in anyone’s book include our treatment of old people, adolescent turmoil and stress, abuse of toxic chemicals, and inequality. For each of these problems, there are—or were, before first contact—many New Guinea societies that found far better solutions.

  These alternative models of human society, unfortunately, are rapidly disappearing. Surely there are no remaining uncontacted populations as large as that of New Guinea’s Grand Valley. When I worked on New Guinea’s Rouffaer River in 1979, missionaries had just found a tribe of four hundred nomads who reported another uncontacted band five days’ travel up the river. In 2011, filmmakers in airplanes captured on video small bands of uncontacted tribespeople in the Amazon rain forest, on the border between Peru and Brazil. Small bands such as those continue to turn up. But at some point within the early twenty-first century, we can expect the last first contact, and the end of the last separate experiment at designing human society.

  That last first contact won’t mean the end of cultural diversity. Much cultural diversity, in fact, has proven able to survive television, travel, and the Internet. But the shift from isolated groups to a global population does mean a drastic loss of diversity. That loss is to be mourned, but there is also a positive side. The fact that our cultures are blending and growing more like one another is cause for hope. Our xenophobia—our fear and hatred of strangers—was manageable only as long as we lacked the means to destroy ourselves as a species. Now that we possess nuclear weapons, it may be best that we learn to see ourselves as members of a shared worldwide culture. Loss of cultural diversity may be the price we have to pay for survival.

  CHAPTER 12

  ACCIDENTAL CONQUERORS

  A LITTLE MORE THAN FIVE HUNDRED YEARS ago, everyone in the Americas was an American Indian. Everyone in Australia was a native Australian, or aboriginal. How did people from Europe come to replace almost all the native people of the Americas and Australia?

  To put it another way, why did technology and political organization develop fastest in Eurasia, slower in the Americas and in Africa south of the Sahara Desert, and slowest in Australia? In 1492 much of the population of Eurasia used iron tools, had writing and agriculture, lived in large centralized states with oceangoing ships, and was on the verge of developing industry. The Americas had agriculture, only a few large centralized states, writing in only one area, and no oceangoing ships or iron tools. Australia had no agriculture, writing, states, or ships. Its people used stone tools like the ones used ten thousand years earlier in Eurasia.

  Nineteenth-century Europeans had a simple, racist answer to those questions. They credited their cultural head start to their being more intelligent than other peoples. They also believed it was their destiny to conquer, displace, or kill “inferior” peoples. This answer is not just loathsome and arrogant; it is also wrong. People differ enormously in the knowledge they gain depending on the circumstances in which they grow up. But no good evidence of genetic differences in mental ability among peoples of different races or cultures has ever been found. Europeans expanded into other continents, and not the other way around, because of technological and political differences, not biological or racial superiority.

  Geography and Civilization

  If there are no genetic differences in mental ability among peoples who originated on different continents, why did civilization develop at such different rates around the world? The answer, I think, is geography. Continents differed in the resources on which civilization depended— especially the wild plant and animal species that became crops and domestic animals. in some continents these useful species could spread from one region to another more easily than in other continents. Geography and biogeography, which is the pattern of species and ecosystems as they are distributed across various regions, have been molding human lives for thousands of years.

  Why do i emphasize plant and animal species? Agriculture and herding brought the disadvantages I describe in chapter 8, but they also made it possible to feed far more people for each square mile of land. Extra food grown by some people and stored to feed others meant that those other individuals could devote themselves to metalworking, manufacturing, writing, and soldiering. Domestic animals provided not only meat and milk to feed people but also wool and hides to clothe them, and power to move people and goods. And by pulling plows and carts, animals made agriculture much more productive than when the only power source was human muscle.

  As a result of agriculture and herding, the human population rose from about ten million in 10,000 BC, when we were all hunter-gatherers, to more than seven billion today. Dense populations were needed for centralized states to rise. Dense populations also led to the evolution of infectious diseases. Some populations exposed to these diseases developed resistance to them, while others did not. All these factors determined who conquered and colonized whom.

  Europeans did not conquer the Americas and Australia because they had better genes. They conquered because they had worse germs (especially smallpox), more advanced technology (including weapons and ships), information storage through writing, and political organization. All these things stemmed from continental differences in geography.

  Different Domestic Animals

  By around 4000 BC, people in western Eurasia already had the “Big Five” domestic livestock animals that are still the most common: sheep, goats, pigs, cows, and horses. East Asians domesticated four other cattle species that replace cows in various regions: yaks, water buffalo, gaur, and banteng. Together, these domestic animals provided food, power, and clothing. In addition, the horse was of enormous military value. it was the tank, truck, and jeep of warfare until the nineteenth century.

  Why didn’t American indians domesticate similar native American species: mountain sheep, mountain goats, peccaries (wild relatives of pigs), bison, and tapirs? Why didn’t indians mounted on tapirs, and native Australians astride battle kangaroos, invade and terrorize eurasia?

  The answer is that it has proved possible to domesticate only a few of the world’s animal species. Many species have reached the first step: being kept captive as tame pets. in New Guinea villages, i routinely find tame possums and kangaroos. i saw tame monkeys and weasels in Amazonian villages. Ancient egyptians tamed gazelles, antelopes, cranes, and even hyenas and possibly giraffes. Ancient Romans were terrorized by the tamed African elephants with which the general Hannibal crossed the Alps.

  But all these attempts at domestication finally failed. Domestication means more than capturing individual wild animals and training them to behave tamely. domestication means breeding animals in captivity—and not just br
eeding them, but choosing which individuals to breed so that their offspring will have desirable features, such as a gentle temper, thick wool, or a willingness to carry loads. By breeding domestic animals over time, choosing individual animals with certain traits, humans turn a wild species into one that is more useful to them.

  Horses were domesticated around 4000 BC, reindeer a few thousand years later. Since then, no large European mammal has been domesticated. Our few modern species of domestic mammals are those that remain after many others were tried and abandoned.

  For domestication to succeed, a wild animal must have certain characteristics. First, in most cases, the animal must be a social animal— which means one that lives in herds or packs. These animals instinctively submit to the dominant animals in their herds or packs, and they can transfer this submissive behavior from animal leaders to humans. In other words, the human owner of a social animal becomes the top animal in the pecking order. Social animals are hardwired to interact with others, even if those others happen belong to a different species. Cats and ferrets are the only solitary, nonsocial animals that have been domesticated.

  Second, animals such as deer that instantly take flight at the first sign of danger, rather than standing their ground, are too nervous to domesticate. Of the world’s dozens of deer species, reindeer are the only ones that have been successfully domesticated. The others were eliminated as possibilities because of their flight reflexes, their territorial instincts, or both.

  Finally, as zoos often discover to their dismay, captive animals may refuse to breed in cages or pens, even if they are well fed and healthy. The problem of getting captive animals to breed has ruined attempts to domesticate some potentially useful species. The finest wool in the world comes from the vicuna, a relative of the camel that lives in the Andes Mountains of South America. No rancher has ever been able to domesticate it, so wool is still obtained by capturing wild vicunas. Princes from the ancient Middle East to nineteenth-century India captured and tamed cheetahs, wild cats that are the world’s fastest land mammals, to use in hunting. But every hunting cheetah had to be captured from the wild, then tamed. Even zoos were unable to breed cheetahs in captivity until the 1960s.

  Together, these reasons help explain why Eurasians succeeded in domesticating the Big Five but not other closely related species, and why American indians did not domesticate peccaries or bison.

  The Revolutionary Horse

  Horses, with their high military value, show how small differences can make one species prized while another species is useless. Horses belong to the order of animals called Perissodactyla, which includes hoofed mammals with an odd number of toes. Horses, tapirs, and rhinoceroses all belong to this order. Of the seventeen living species of Perissodactyla, all four tapirs and all five rhinos, plus five of the eight wild horse species, have never been domesticated. Africans or American indians mounted on fighting rhinos would have trampled european invaders—but it never happened.

  A sixth wild horse relative, the wild ass of Africa, gave rise to domestic donkeys, which proved splendid as pack animals but useless as military chargers. The seventh wild horse relative, the onager of western Asia, may have been used to pull wagons for a few centuries in ancient times, but all descriptions mention its vicious temper. As soon as Asians could replace them with domesticated horses, they gave up trying to use the troublesome onagers.

  Horses revolutionized warfare in a way that no other animal, not even elephants or camels, ever rivaled. Hitched to battle chariots, horses became the unstoppable tanks of the ancient world. After the invention of saddles and stirrups made it easier for people to ride horses, cavalry (soldiers mounted on horseback) became a vital military asset. The mounted warriors of Attila the Hun devastated the Roman Empire, the riders of Mongol leader Genghis Khan conquered an empire that stretched across Russia and China, and military kingdoms with cavalry troops arose in West Africa.

  A few dozen horses helped the Spanish conquistadors Cortés and Pizarro, each leading only a few hundred Spanish fighters, overthrow the two most populated and advanced American states: the Aztec Empire in Mexico and the Inca Empire in South America. The military importance of this most universally prized of all domestic animals finally ended after six thousand years, in September 1939, when Polish cavalry riders spurred their steeds into doomed charges against the invading German armies of Adolf Hitler.

  EXTINCTIONS THAT SHAPED HISTORY

  IN THE SIXTEENTH CENTURY, HORSES HELPED the Spanish conquistadors Cortés and Pizarro conquer the two most powerful empires in the Americas: the Aztecs and the Incas. Because the Americas had no native horses, Aztec and Inca warriors were unprepared for the terrifying sight of conquistadors mounted on charging steeds. Wild horses similar to the ancestors of the conquistadors’ horses, however, had once been native to the Americas. If those American horses had survived, the Aztec and Inca leaders might have surprised the Spanish invaders with cavalry charges of their own. But, in a cruel twist of fate, America’s horses had become extinct long before, along with 80 to 90 percent of the other large mammal species of the Americas. (Wild horses in the Americas today descended from herds brought by European explorers and settlers.)

  The mass mammal extinction happened around the same time that the first human settlers, the ancestors of modern Indians, reached the American continents. The Americas lost not only horses but other species that might have been domesticated, including large camels, ground sloths, and elephants. The same thing happened in Australia, where large mammals disappeared around the time the first people arrived. Australia and North America wound up with no domestic species at all, unless the Indians’ dogs were the descendants of North American wolves. South America was left with only the guinea pig (used for food), a relative of the camel called the alpaca (used for wool), and another camel relative called the llama (used for carrying loads, but too small to carry a rider).

  No native American or Australian mammal ever pulled a plow, a cart, or a war chariot. None ever gave milk or carried a rider. After the civilizations of Eurasia and Africa had harnessed the power of animal muscle, wind, and water, the civilizations of the Americans limped forward on human muscle power alone.

  As you’ll see in part 5 of this book, scientists still debate whether hunting by the first human settlers in Australia and the Americas caused the mass extinction of large mammals in those continents. Whatever the cause, the extinctions made it almost certain that the descendants of those first Australians and Americans would be conquered, thousands of years later, by people from Eurasia and Africa—the continents that kept most of their large mammal species.

  Spanish conquistador Hernán Cortés rides triumphantly into a Mexican city. Mounted warfare helped the Spanish overthrow the powerful Aztec and Inca states in the Americas, where horses were unknown.

  Plant Power

  Plant foods played a vital role in the rise of civilizations. In fact, most of the calories consumed by the human race still come from plants—specifically, from cereals, which are grasses with edible starchy seeds, such as barley kernels or wheat grains. But as with animals, only a tiny fraction of all wild plant species has proved suitable for domestication.

  Why were some plants easier to domesticate than others? For one thing, some plants are self-pollinators, which means that a single individual plant can pollinate itself, or fertilize its own seeds. These plants, including wheat, can produce their offspring on their own. Other plants, such as rye, are cross-pollinators, meaning that pollen from one plant must reach a different plant. Self-pollinators were domesticated earlier and more easily than cross-pollinators. People found it easier to select and maintain desirable strains of selfpollinators, because these plants did not constantly mix with their wild relatives, as cross-pollinators did.

  Australia was relatively poor in native plants suitable for domestication. That may explain why the aboriginal Australians never developed agriculture. But it’s not so obvious why agriculture in the New World of the
Americas lagged behind agriculture in the Old World of Eurasia and Africa. After all, many food plants that are now important around the world originated in the New World: corn, potatoes, tomatoes, and squash, to name just a few. The answer to the puzzle calls for a closer look at corn, the New World’s most important crop.

  Next to a quarter, an ear of teosinte (left) is much smaller than an ear of modern corn (right). It took thousands of years for the major grain of the Americas to evolve into a form that could support large populations.

  All civilizations have depended on cereals, but different civilizations have domesticated different cereals. In the Middle east and europe, the grains were wheat, barley, oats, and rye. in China and Southeast Asia, they were rice, foxtail millet, and broomcorn millet. in Africa south of the Sahara Desert, they were sorghum, pearl millet, and finger millet. But in the New World, only corn.

  Soon after Columbus’s voyage to America, early explorers took corn back to europe. it spread around the globe, so that now more acres are planted in corn than in any other cereal except wheat. Corn is the most important crop in the United States today. Why, then, didn’t corn let the civilizations of the American Indians develop as fast as the Old World civilizations that were fed by wheat and other cereals?

  Corn was a much bigger pain in the neck to domesticate and grow, and it gave an inferior product. Those will be fighting words if you, like me, love hot buttered corn on the cob. Hear me out on the differences between corn and other cereals.

  The Old World had more than a dozen wild grasses that were easy to domesticate and to grow. These grasses had large seeds. It was easy to harvest many stalks at a time with sickles, easy to grind the seeds and prepare them for cooking, and easy to sow seeds for next year’s crop. These grains were already productive in the wild. You can still harvest up to seven hundred pounds of grain from each acre of wild wheat growing naturally on Middle Eastern hillsides. In a few weeks a family could harvest enough to feed itself for a year. Even before wheat and barley were domesticated, villages had invented sickles, mortars and pestles for grinding, and pits for storing grain. They supported themselves on wild grains.