Wired for Culture: Origins of the Human Social Mind (7 page)

Even in humans, a theory of mind emerges only sometime around a child’s third or fourth year. A procedure known as the Sally-Anne test shows a child two dolls: Sally and Anne. Sally has a marble that she (with the help of a human experimenter) puts in her basket. Then Sally leaves the scene. While Sally is away, Anne takes the marble from Sally’s basket and puts it in her box, which differs in appearance from Sally’s basket. Sally then returns and the child is asked where Sally will look for the marble. Children younger than three to four say she will look in Anne’s box (intriguingly, many people who suffer from autism also respond this way). But older children realize that Sally can have beliefs that differ from theirs, and they correctly say she will look in her basket.

There are many varieties of these “false-belief” tests, and they can be difficult to interpret, but they all point to three to four years of age as being a critical period during which children’s awareness of others’ minds develops. To be fair to the other animals it must be allowed that some of them, especially some birds, behave as if they have an awareness of what others are thinking. For instance, if the small bird known as the nutcracker (and some other jay and crow species) sees another bird watching it while it hides its food, it will return alone later to hide the food in a new spot. What matters for this discussion, though, is that no other animal ever seems to get as far in their understanding of others’ minds as a four- to five-year-old human. Even among the Great Apes, any theory of mind seems to be no more advanced than that of a human two-year-old.

It is staggering and baffling to us that other animals could be so dim-witted. It is not that they are stupid: a chimpanzee is better at being a chimpanzee than you are. It is just that they lack social learning, and this small difference has made all the difference. But what of our more recent ancestors, such as the many now-extinct species in the
Homo
lineage? The African Rift Valley is an angry tear in the Earth’s crust that stretches for thousands of miles. It was in a part of the Rift Valley in Tanzania called the Olduvai Gorge that the pioneering archaeologist Louis Leakey discovered objects over 1 million years old that appeared to have been deliberately and intentionally shaped by hands. Later work established that these were
Homo erectus
hand axes, and they were often found near to bones with cut marks on them made by the same hand axes. For many archaeologists this time in our history, perhaps 2 million years ago, is one of those defining moments, a time we can look back on romantically as being the moment that creative thinking arose. These early humans, it seems, had acquired not only a compulsion to make things but also the insight that they could alter and improve them. It is that “light bulb” moment in Stanley Kubrick’s
2001: A Space Odyssey
when the ape throws a bone up into the air. We watch it tumbling end over end, and as it falls back to the ground the bone transforms into a spaceship on an interstellar mission.

But the archaeological record tells a more prosaic story about our ancestors’ creativity. Remarkably, from careful sifting through layers of strata, archaeologists have been able to determine that our
H. erectus
ancestors living on the African savannah stubbornly chipped the same hand axes out of larger stones for nearly all of their 1.8 million-year history, without making any serious alterations to its form or function. For tens of thousands of generations of parents and their offspring, and the individuals watching them, this species produced the same basic tool. Their culture—their toolkit—wasn’t evolving, and this is not what we expect of an animal with social learning. It is not even clear that the Neanderthals possessed the capabilities for social learning, or if they did, they were not nearly as sophisticated as ours. The Neanderthals would have been recognizably similar to us, yet hauntingly different, being stocky and muscular, with large bulbous noses. But despite having brains at least as big as ours, the Neanderthals lacked most of the outward signs of sophisticated culture so common to modern human archaeological sites of the same period. The Neanderthals did not produce any art, they didn’t have musical instruments, and there is no evidence that they carved figures.

Chauvinism? Some will say yes, and the Neanderthals have their apologists. But at a time when modern humans were overflowing with sophisticated artifacts, there is no evidence that Neanderthals could engrave or shape bones, they had no sewing, no weaving, no bows and arrows, and no spear throwers, even though they would have been able to observe all of these things among the talented newcomers who had moved in right alongside them. Some Neanderthal archaeological sites yield shaped pieces of shells that might have been used as jewelry, and other sites suggest that they added symbolic objects such as flowers to graves. (Burial itself should not be taken as any sort of religious, spiritual, or symbolic act. Dead bodies decay rapidly and attract flies and predators, so burial is simply a prudent thing to do.) But even these practices seem only to appear when Neanderthals had prolonged exposure to modern humans, and very recent evidence suggesting that Neanderthals actually produced and wore pieces of jewelry is now being reinterpreted as the work of
Homo sapiens
. The paleontologist Chris Stringer has even speculated on a BBC radio program that if there were slight changes in some Neanderthals’ capabilities late in their history, this might reflect brain genes they had acquired from their interbreeding with modern humans.

This description of the Neanderthals is not what we expect of a species with true social learning. No one can be sure, but we can only guess that the mental life of the Neanderthals was, and still is for all other animals, a plodding, inflexible, literal, and unimaginative existence, at least compared to ours. While we were spreading around the world, the Neanderthals’ limited technologies meant they were confined almost exclusively to the environments of Western Europe, parts of the Middle East, and southern Siberia. While we were using sophisticated spears and arrows to hunt large mammals, the Neanderthals were close-range hunters with short spears for jabbing, or who relied on clubbing or stoning their large prey—and each other—to death. The Neanderthals’ famously robust and muscular physique probably speaks volumes about their lack of cultural complexity, while our gracile and refined appearance trumpets our virtuosity at substituting tools and clever thinking for brute physical force.

The Neanderthals’ stocky build made them well adapted to the cold climates of much of Europe and Eurasia, but the irony is that our species—whose tall and slender bodies were certainly not cold-adapted—replaced the Neanderthals during the Ice Age that engulfed these lands. It seems the Neanderthals simply could not adapt their lifestyle of hunting for large game rapidly enough to the declining populations of large animals that the encroaching ice would cause. But we could, and the difference is probably down to social learning. Or think of it this way. Twenty-eight thousand years ago, the Neanderthals sat in Gibraltar going extinct while gazing across the straits to the warmer climes of Africa clearly visible only eight to ten miles away, but they were unable to make boats to carry them there.

CUMULATIVE ADAPTATION AND
CULTURAL SURVIVAL VEHICLES

THE NEANDERTHALS’
plight reminds us that each of the many biological species on Earth exploits its particular environment, but for the most part it is
only
that environment that it can occupy. This is because biological species are vehicles built by sets of genes that have evolved together over millions of years to be good at solving the problems posed by a particular environment. For instance, woolly musk oxen are the product of a coalition of genes that natural selection has roped together to produce a vehicle suited to surviving the cold temperatures of Siberia. A different coalition of genes gives rise to camels, a vehicle good at surviving even the scorching deserts of the Sahara; monkeys are vehicles adapted to climbing trees; and the coalitions of genes we call penguins produce a fishlike bird vehicle that can survive the Southern oceans. A camel would make a poor musk ox and a penguin a poor monkey. A cross between a musk ox and a camel—were one possible—probably wouldn’t be much good at being either a camel or a musk ox.

The lesson we learn from this is that there are no real shape-shifters in nature, nor anything like children’s Transformer toys that can change what they are. Being limited to what their coalitions of genes evolved to do, no one species can do everything. That was, of course, until humans came along and rewrote all the rules that had held for billions of years of biological evolution. Here was a single biological species using just a single coalition of genes that was nevertheless able to adopt different guises and forms in different places. In one place we could be like a heron able to pull fish from the sea, in another like a lion able to bring down large prey, in another like a camel able to survive in the desert, and in yet another we could float on the water like a duck or a seagull. Our cultural survival vehicles were built not from coalitions of genes but from coalitions of ideas roped together by cultural evolution. This meant that for the first time a single species was able to spread out and occupy every corner of the world. Where all those species that had gone before us were confined to the particular genetic corner their genes adapted them to, humans had acquired the ability to transform the environment to suit them, by making shelters, or clothing, and working out how to exploit its resources.

It was social learning that made our shape-shifting possible because social learning is to ideas what natural selection is to genes. Both are ways of picking out good solutions from a sea of variety. Natural selection builds complex adaptations like eyes and brains from the successive accumulation over millions of years of many small genetic changes, each one of which improves on its previous form. Equally, social learning builds complex societies by a process of cumulative cultural adaptation as people select the best from among a range of options, improve on them, or blend them with others—what Matt Ridley in his book
The Rational Optimist
calls “ideas having sex.” And so our knowledge, ideas, technologies, and skills accumulate and build increasingly complex objects. When someone noticed that a club could be combined with a hand ax the first hafted ax was born. When someone tied a vine to the ends of a bent stick, the first bow was born and you can be sure the first arrow soon followed.

The analogy with genetical evolution is deeper than mere words: just as genetical evolution brings together the sets of genes that produce a successful biological species or vehicle for a particular environment, cultural evolution brings together the sets of ideas, technologies, dispositions, beliefs, and skills that over the millennia have produced successful societies, good at competing with others like them, and well adapted culturally to their particular locale. These are our cultural survival vehicles, and it is important to see them as not different in principle from biological vehicles, it is just that the information on which they are based takes a different form: it resides in our minds rather than in our genes. Thus, when people walked into the Arctic and survived, it was because they had acquired the knowledge and technology to make clothes suitable to that harsh environment, to build shelters out of ice, and to fish in the cold Arctic waters. At a later time and different place, when Polynesian people invaded the Pacific, it was because they had acquired the technology to produce seagoing boats, and the knowledge of how to navigate by the stars.

Indeed, we can think of our differing cultural survival vehicles as playing the same ecological role as different biological species. Just as a camel would make a poor musk ox, a Polynesian would not be well equipped to survive the Arctic. But of course our cultures can adapt on the fly and without having to wait for genetic changes to come along, and so the rapid spread of our various cultural species around the world after we left Africa is like a tape of biological evolution speeded up a millionfold or more. Almost everything around us today in our modern world can be attributed to social learning and the cumulative cultural adaptation it propels.

This is not to say our genes played no role in our occupation of the world, just that it was our cultures that took us to its various environments to begin with. When people walked into the Arctic, they began to evolve genetically to have a stocky build that made them better at retaining heat, but it was their culture and not their genes that took them to the Arctic to begin with. Similarly, the Polynesians would also adapt genetically to their hot and sunny environment by becoming leaner and darker-skinned, but again it was their culture that got them there.

Modern genomic studies of large numbers of people are discovering many small genetic differences among human groups that confer some sort of advantage in their environments. For example, in some European and African societies with a long history of dairying, adults have acquired the ability to digest milk. We have seen how some Tibetan people have acquired an extraordinary capacity to extract oxygen from the air at high altitudes, and how some Han Chinese have an unusual ability to metabolize alcohol. Hunter-gatherer groups exposed to more starch in their diets produce more salivary amylase—an enzyme that begins the process of digestion while food is still being chewed—than those whose diets contain less starch. Differences in facial appearance around the world might be related to arbitrary preferences in the choice of mates.

These are just some of the many small genetic differences among human groups that have arisen as a result of being thrust into environments that our cultures opened up to us. And it is remarkable how quickly we have adapted. The 60,000 to 70,000 years since modern humans spread out of Africa is little more than the blink of an eye when stacked against the 6 to 7 million years that separate us from our Great Ape ancestors. The presence of these genetic differences, however small, tell us that we have had a habit of keeping to ourselves as we spread out around the world, because had we not, our genetic differences would have become blurred. This is not to deny that human groups have always traded with each other, intermarried, fought wars, and traipsed across each other’s territories. But it is only by having a tendency to maintain our identities in separate cultures or tribal groups that natural selection could have sculpted our many differences, and have done so in just the few tens of thousands of years since we walked out of Africa. Then again, we might have guessed this was the case: how else but through a tendency to keep to ourselves in our cultural survival vehicles can we explain a single species that speaks at least 7,000 mutually unintelligible languages?