• Choose a category
• All
• Classic-Fiction

By Root 427 0

members. But no animal is more social and lives in larger groups than man. There are many advantages to larger groups, but there is one serious disadvantage: negotiating relationships with all the members of the group. Rewarding friends, seeking allies, and avoiding enemies all require more brainpower as the group gets larger. Researchers have found that the larger an animal’s group size, the larger the percentage of the brain devoted to the neocortex (the outer layer of the brain, which accounts for most cognitive abilities). For most mammals, the neocortex makes up 30-40 percent of the brain. For highly social primates, such as chimpanzees, the percentage rises to 50 to 65 percent. For humans, the neocortex takes up a staggering 80 percent of the brain (and our brains are seven times larger than you would expect for a mammal of our size).

According to social brain theorists, the size of human groups also played a key role in the evolution of language. For other primates, the glue that keeps the group in relative harmony is grooming—that staple activity of animal behavior, for example, when one chimpanzee combs through the hair of another to untangle fur or remove nits. This is done not just for reasons of hygiene but also to reaffirm the social bond between the two. Primatologists have charted a linear relationship between the size of the group and the amount of time spent grooming. But grooming is time consuming, too time consuming for humans once their group size began to grow beyond fifty. Imagine trying to use grooming to hold together a large corporation. Nothing would ever get done. So, language came to serve as a kind of accelerated social grooming, allowing group members to maintain relationships on a much larger scale. For social brain theorists, language developed not primarily for informational tasks, such as where to find a wildebeest, but so that we could gossip about one another. Gossip served not as a distraction from the task at hand but as the main business, establishing and defining our relationships with other members of the group. Who shares meat, which person can’t be trusted, who cheats on whom. Gossip became the means of handling our ever-expanding social networks. Lest you think we have evolved beyond that today, studies show that fully 60-70 percent of our conversations are devoted to social topics (i.e., gossip).

Of course, as Ekman’s eighteen lying smiles already revealed, social life and gossip are firmly intertwined with deception. You see, a larger neocortex doesn’t just predict the size of a species’ social group. It also predicts how much that species uses duplicity and social manipulation. The proponents of the social brain theory are still wrestling with perhaps the central question it raises about our development: is our brain growth directed more toward enabling us to connect with one another or more toward allowing us to manipulate one another? Now you can see why this theory is also called Machiavellian.

If we take Darwin’s idea of sexual selection seriously, though, we can narrow the driving force behind brain growth even further. We may, in fact, be able to pin it entirely on the need to find a mate. In other words, the central purpose behind our enormous brains may be to help us negotiate the unruly world of dating. Evolutionary psychologist Geoffrey Miller, a leading proponent of this theory, has even gone so far as to call the human mind a “protean courtship device.”

The reason mating is a plausible force behind our brain growth is because of something known as runaway sexual selection, which occurs when both the trait and the preference for the trait are heritable. In this case, if the main social difficulty that we face as a species is securing a mate, and if the most essential trait to accomplish that is our intelligence, and if intelligence is heritable, then sexual selection will lead to greater intelligence. And if the preference for intelligence is also heritable, then sexual selection will boost human intelligence even more dramatically (this is where it becomes