The Social Brain and Its Implications

We sometimes imagine that the human social world is unlimited, a product of our species’ unique capacity for culture. In fact, it turns out to be a great deal more restricted in size than we suppose. In this respect, we humans are simply part of a continuum of social complexity that runs through the primates. Our social world is (a little) bigger than that of other primates only because we have a (proportionately) larger brain. Even so, it is still a very small-scale world—our natural social world is no more than about 150 people, even when we live in modern cities. There are nonetheless some aspects of the human condition that are unique. These mainly have to do with the fact that ensuring the cohesion of groups as large as those we find in modern humans has required new mechanisms. And it is here that culture has played its biological role.