War: What is it good for? (53 page)

By half a million years ago, one of these protohuman variants—known, after its original find spot in Germany, as Heidelberg Man—had evolved brains almost as big as ours, and over the next few hundred thousand years Neanderthals (also named after an original find spot in Germany) actually grew brains bigger than ours, albeit flatter, with some areas therefore less developed. One or both species might have communicated in ways we would call speech, and they definitely found new ways to kill, using resin and sinews taken from other animals to attach stone spearheads to wooden shafts.

Archaeologists have found enough Neanderthal skeletons to know that they were very, very violent. At least two skulls bear healed traces of nonfatal stabbings. Stone spearheads are common on Neanderthal sites, and head and neck traumas even more so. The closest parallel to Neanderthal bone breakage patterns comes in fact from modern rodeo riders—but since there were no bucking broncos a hundred thousand years ago, we probably have to assume that Neanderthals got hurt fighting. Possibly all these fights were against their prey, but since their prey sometimes included other Neanderthals—the evidence of occasional cannibalism is overwhelming—it is hard not to suspect that the big-brained Neanderthals were the most
violent of all the great apes. Clever, well armed, and extraordinarily strong (two leading archaeologists describe them as “combining [the physique] of a powerful wrestler with the endurance of a marathon runner”), by 100,000
B.C.
they had extended their range from central Asia to the Atlantic.

But then along came us.

2.7 Pounds of Magic

Inside your head is a little piece of magic. Nothing else in nature can compare with the 2.7 pounds of water, fat, blood, and protein pulsing away inside your skull, guzzling energy and fairly crackling with electricity. Four hundred million years in the making, this brain sets us apart from every other animal on earth and has changed everything about the place of force in our lives.

Archaeologists and geneticists agree that this miracle of nature took on its fully modern form in Africa somewhere between 200,000 and 50,000 years ago. This was a time when new twigs were sprouting off the protohuman branch of the tree of life with particular vigor, perhaps because an extremely unstable climate kept changing the payoffs in the games of life and death.

It was a wild ride: temperatures 200,000 years ago were distinctly cooler than today's (on average, perhaps 3°F lower), but then, amid many wild zigs and zags, they tumbled into a genuine ice age. By 150,000 years ago, the world was 14°F colder than today. Mile-thick glaciers blanketed much of northern Asia, Europe, and America, tying up so much water that the sea level fell three hundred feet below what we are used to. No one could live on the glaciers, and the vast arid steppes around their edges, where winds howled and dust storms raged, were little better. Even near the equator, summers were short, water was scarce, and low levels of atmospheric carbon dioxide stunted plant growth.

Humans that looked just like us, with high, domed skulls, flat faces, and small teeth, first walked the earth in these years. Excavated fossil remains and DNA studies both agree on this, suggesting that the first modern humans evolved in East Africa between 200,000 and 150,000 years ago. The odd thing about the earliest finds, though, is that while these great apes chipped stone tools, hunted and gathered, and fought and mated, little we find on their sites is very different from what we find on sites belonging to Neanderthals or other protohumans. Just why this is remains hotly debated,
but it was not until after the world had warmed up for a few millennia and then crashed into another ice age that humans started acting like us as well as looking like us.

Beginning between 100,000 and 70,000 years ago, odd things start turning up on archaeological sites. People were now decorating themselves, something previous protohumans did not do. They collected eggshells and spent hours chipping and grinding little disks out of them. Using just a pointed bone, they would drill a hole through the middle of each disk and string hundreds together in necklaces. They swapped these ornaments with each other, sometimes trading them across hundreds of miles.

Protohumans were acting a lot less proto and a lot more human. They gathered ocher, a kind of iron ore, and used it to draw bold red lines on cave walls and probably on each other's bodies. At Blombos Cave in South Africa someone even scratched simple geometric patterns onto a little stick of ocher seventy-five thousand years ago—making it not just the oldest known work of art but also a work of art used for making other works of art.

People coaxed their fingers into producing tiny tools, lighter and subtler than anything seen before, and then used some of the tools as weapons. The oldest known carved bones include fishhooks, and among the oldest known stone bladelets (as archaeologists call the tiny tools) are arrowheads and javelin points. Bird and fish bones from caves along Africa's southern shores show that people used these devices to kill prey that had previously been beyond their reach (remains of their shoulder and elbow joints suggest that Neanderthals, for all their fierceness, could not throw very well, let alone shoot arrows).

Like Neanderthals, early
Homo sapiens
also occasionally ate their own kind, using stone blades to carve the flesh off meaty long bones and stone hammers to crack bones to extract marrow and the tastiest treat of all, the miraculous human brain. A steady trickle of bashed-in skulls uncovered by archaeologists strongly suggests that humans were killing each other, but we have to wait until thirty thousand years ago to find decisive evidence. This comes not from mutilated skeletons but from the famous paintings that
Homo sapiens
began leaving on cave walls in northern Spain and southern France. These are things of exquisite beauty. “None of us could paint like that,” Picasso is supposed to have said when he first saw them. “After Altamira, all is decadence.” However, some of them have a dark side too, showing unmistakable scenes of humans shooting each other with arrows.

Archaeologists excavating sites between 100,000 and 50,000 years old occasionally find objects that look distinctly modern, such as jewelry or art, but sites younger than 50,000 years almost always include such artifacts. People were doing new things, finding new ways to do old things, and inventing multiple ways to do everything. From Cape Town to Cairo, pre-50,000-
B.C.
sites all look rather alike, with much the same kinds of finds used in much the same kinds of ways. Post-50,000-
B.C.
sites, however, vary wildly. By 30,000
B.C.
, the Nile Valley alone hosted half a dozen distinct regional styles of stone tools.

Humans had invented culture, using their great, fast brains to weave webs of symbols that not only communicated complex ideas—Neanderthals and perhaps even
Homo ergaster
could do that—but also preserved them through time. Modern humans, unlike any other animal on earth, could change how they thought and lived in ways that accumulated, with one idea leading to another and mounting up across the generations.

Culture is a product of the biological evolution of our big, fast brains, but culture itself also evolves. Biological evolution is driven by genetic mutations, with the mutations that work best replacing those that do not across thousands or even millions of years. Cultural evolution, however, moves much faster, because unlike the biological version, it is directed. People face problems, their little gray cells go to work, and ideas come out. Most ideas, like most genetic mutations, end up making little difference to the world, and some are downright harmful, but over time ideas that work well outcompete those that do not.

Imagine, for instance, that you were a young hunter in the Nile Valley thirty thousand years ago. In my made-up game of death earlier in this chapter, I used “doves” as symbols for animals that never fight and “hawks” for those that always fight; here, I will use “sheep” to represent people who follow the herd and “goats” for those who don't. Our young hunter is a goat, certain that he knows best, and he thinks up a new design for arrowheads. Let us say that his version has longer tangs, so that it will stay lodged in the flank of a wounded antelope better than the old style. To his astonishment, though, his sheepish associates pooh-pooh his idea, telling him that the ancestors didn't need long tangs, so neither do we.

Like fight and flight in the dove-and-hawk game, innovation and conservatism both have costs and benefits. Innovators pay a price: it takes time to learn to make new arrowheads and to use them properly (costing, let us say, 10 points), and—perhaps more seriously—going against the way things have always been done might lose them respect (–20 points). Other men
might not want to cooperate on hunts with someone so quirky, in which case the goatish inventor might actually end up with less meat, despite having better technology (another –10 points). In the end, he might just let the whole thing drop.

Unless, that is, the gains outweigh the losses. If his arrowheads really do produce more kills, he not only gains weight by eating more (say, +20 points) but also can gain prestige by sharing antelope steaks generously (+25 points). Such a successful man might get more sex (a further +10 points), which will put the balance firmly in the black (at +15 points). Over several generations he might spread his ingenious, goatish genes through the little hunter-gatherer group; but cultural change will overtake biological change long before that happens, because the other men in the band will simply copy his arrowheads. The inventor's tally of points and luck with the ladies will then decline, but perhaps not quite back to zero, because now everyone is eating better—unless, of course, the hunters' new technology is so effective that it kills off all the antelopes, setting off new chains of consequences …

Like the dove-and-hawk game, this is fun to play. We can make the story branch off in all kinds of directions, because even small changes in the payoffs produce big changes in the results. But the point, as with the earlier game, is that in real life the sheep-and-goat game is played over and over, with different results each time. If the costs of going against tradition are high in the inventor's band, the arrowhead will not catch on, but if it really is a better arrowhead, people in other bands will also think of it, and before long it will catch on somewhere else. Goatish bands might then out-hunt sheepish ones, forcing the latter either to switch arrowheads after all, or change their diet, or fight the innovators—or in an uncaged landscape they could just move away.

Culture wars of this kind are uniquely human. Although some other animals can be said to have cultures (particularly chimpanzees, among whom each community does things slightly differently from its neighbors), none seem to be capable of cumulative cultural change. The evolutionary consequences of culture have been a bit like those of the rise of sexual reproduction 1.5 billion years ago: where sex sped up genetic mutation, culture sped up innovation. Both mechanisms vastly increased the diversity of outcomes, allowing cells or humans to cooperate and compete on a bigger scale.

Armed with brains powerful enough for cultural evolution, modern humans conquered the world. A few
Homo sapiens
had drifted out of
Africa just before 100,000 years ago, when culture was still a fragile flower, and perhaps because of this these early emigrants only got as far as what we now call Israel and Arabia. There they lived alongside Neanderthals, although not necessarily happily: the oldest known fatality from a spear thrust, around 100,000 years ago, was one of these pioneers. But a second wave, which broke out of Africa about 70,000 years ago, took the full package of modern human behavior with it and spread across the planet fifty times as fast as the protohumans who had left Africa nearly 1.6 million years earlier.

Culture gave the new migrants huge advantages over protohumans. When modern humans arrived in Siberia thirty thousand years ago, for instance, it was even colder than it is now. But unlike other animals, they did not have to wait millennia while their genes evolved toward hairiness to keep them warm. Instead, they invented bone needles and gut threads and sewed fitted clothes. There might have been conservatives who preferred traditional, ill-fitting skins to this new look, but the first winter either changed their minds or killed them.

This process explains not only why there is so much cultural variety around the world (slight variations in local conditions, combined with the random generation of good enough ideas, produced countless different evolutionarily stable strategies) but also why there is so much similarity (competing cultures tend to converge on a few winning strategies). And as well as being humanity's best tool for adapting to new environments, culture was the greatest force for transforming those environments. It transformed them so much, in fact, that all the protohumans in the world went extinct.

It is unsettling to think about what this involved. On the one hand, there is no hard evidence that our ancestors actively drove protohumans extinct, and DNA analysis hints that there might have been cooperation between species. The Neanderthal genome, sequenced in 2010, shows that
Homo sapiens
and Neanderthals mixed their body fluids sufficiently often that 1–4 percent of the DNA of everyone of Asian or European descent comes from Neanderthal ancestors, while 6 percent of the DNA in Australian Aboriginals and New Guineans comes from Denisovans, a kind of protohuman that was only discovered in March 2010. On the other hand, we have no way to tell how many of these couplings were rapes—or whether, when we find smashed Neanderthal skulls, the hand that wielded the murder weapon belonged to another Neanderthal or to a
Homo sapiens
. But whether or not modern humans hunted down their rivals, it is all too easy
to imagine how our inventiveness would have made life impossible for slower-witted kin who needed the same food.