People used to think that the infant’s mind was completely empty at birth, and then filled up with information from the world around. The eighteenth-century English philosopher, John Locke, described the mind of a newborn infant as a blank piece of paper upon which experience would write itself.2 William James, the nineteenth-century American philosopher, thought the newborn’s world was a chaotic jumble of confusion.3 Both were wrong in assuming that a baby has no built-in abilities and that all experience is total chaos. Natural selection has been busy creating human brains ready for certain information. Like your laptop computer delivered through the mail, babies come with a brain operating system that has evolved to learn certain things about the world and ignore other stuff that is not of use to them. And the most important things to a human baby are other humans. Human infants are wholly dependent on others and, as mentioned, spend the longest proportion of their lives in this state of dependency compared to any other species. Why?
Approximately 250,000 years ago, a few thousand Homo sapiens migrated out of Africa aided by a brain that was sophisticated enough to adapt to new environments, but also one that had evolved the capacity for the transmission of knowledge from one generation to the next. We were born to learn. Long before writing and the Internet were invented, humans had the capacity to communicate with each other in ways that no other animal could. With communication came an explosion in technology and skills. This was not information in our genes but rather knowledge gleaned from others. Our parents, and their parents and their parent’s parents before them, had thousands of years of knowledge passed down from each generation. That’s why every newborn baby does not have to start from scratch. This is such an obvious fact about human civilization that we often forget that we are the only animals on this planet that retain skills and knowledge that we pass on to our offspring. Other animals can learn about their environments but no other animal has the human capacity for acquiring thousands of years of experience within a lifetime.
The best way to tap into that knowledge is to pay attention to others, which is why humans spend so much time as children. Other species that spend comparatively longer periods as juveniles also end up smarter than their cousins who reach adult maturity more quickly. For example, crows are a remarkably clever family of birds that are capable of solving many more complex problems that behavioural bird experts throw at them compared to other birds, such as chickens. After hatching, chickens are up and pecking for their own food much faster than crows, which rely on the parent bird to bring them food in the nest. However, as adults, chickens have very limited scavenging skills whereas crows are much more flexible in foraging for food. Crows also end up with bigger and more complex brains, which is why they are sometimes referred to as the ‘feathered apes’ because they are as clever as chimpanzees. Their extended fledging period enables them to develop intelligence. Across various animals, childhood has been compared to the research and development phase of the life cycle.4 Those species that spend longer in R&D end up with a larger repertoire of skills and not surprisingly, also end up the most sociable.
In humans, not only do we learn from others about the world around us, we also learn to become a self. In the process of watching others and trying to understand them, we come to discover who we are. During these formative years, the illusion of the reflected self we experience is constructed by those around us through our social interactions.
On the Face of It
Brains got bigger as a way of coping with the processing demands of increasing group size. You need big brains to think about people so that you can negotiate the best path through the social landscape. You have to be cunning and that requires the ability to anticipate what others are thinking. In order to be a successful Machiavellian primate,5 as another famous Italian, Don Corleone, would say, ‘You need to keep your friends close but your enemies closer still.’ In other words, you have to be vigilant for those who wish to take advantage of you.
One of the first things you need to do is identify important individuals in the group. You have to be choosey. It’s no good trying to apply the same interactions to everyone. Imagine the problems you would create if you were a sexually active male, and could not distinguish between your mother, sister and your girlfriend when it came to sexual advances. It is important from an evolutionary point of view (not to mention social cohesion) to distinguish between individuals and one of the most important ways humans identify others is to rely on the uniqueness of faces.
Faces are an unusual class of patterns because they all share the same basic structure of two eyes, a nose and a mouth. Yet despite the similarity, the average human can recognize thousands of separate faces. This facial expertise is supported by neuronal circuitry in a region known as the fusiform gyrus, a cortical region located just behind your ears.6 It is active when we look at faces, and if you are unfortunate enough to have this area damaged (especially on the left side), then you may suffer from a condition known as prosopagnosia, a kind of face-blindness. Prosopagnosics can no longer tell faces apart and fail to recognize those that were once very familiar.
Our love of faces begins very early. Like Lorenz’s goslings that followed the first moving thing they saw, human newborns have built-in brain circuitry for following faces.7 Even though their vision is bad enough to qualify them as legally blind, faces are like magnets to young babies. They can hardly take their eyes off a human face even if it is just a rudimentary pattern made up of two dots for eyes and a third for a mouth. This initial preference for face-like patterns is quickly replaced by a system that learns to recognize specific faces. By six months, if you show infants a face they have never seen before, they easily remember it much later. They are learning who’s who. But it’s not just human faces. Six-month-old infants recognize both human and monkey faces. However, by nine months, babies lose the ability to tell the difference between monkey faces much as we do as adults.8 It’s another example of a sensitive period with brain plasticity that becomes increasingly tuned in to experience. What is remarkable (but not if we remember that we, too, are primates) is that baby monkeys also seek out any face, either monkey or human, but become more tuned into those to which they are exposed. We know this from studies of monkeys raised without seeing faces in laboratories where the human handlers wore blank masks to cover their faces.9 If monkeys never see faces, they lose the ability to tell any faces apart. If they see only human faces, they get good at telling humans apart. This selective responding to faces is another example of the ‘use it or lose it’ principle, in which the neural networks are tuning into early experiences to create a permanent record.
Early face experience also shapes human brains. For example, children born with cataracts never see faces clearly as infants. When their vision is surgically corrected later in life, they still have problems with recognizing faces even though they can then see clearly.10 No matter how much training and practice you have later in life, some early exposures are important for shaping brain development. So when Tarzan returned from the jungle to take up his position as Lord Greystoke, he would have had a problem telling the difference between the cook and the scullery maid, having never seen a human face as an infant. His recognition for ape faces at the zoo, on the other hand, would have been just fine.
The same goes for telling the difference between individuals from another race. Unlike most adults who think members of other ethnic groups look very similar, babies initially have no problem. They can tell everyone apart. It is only after exposure to lots of faces from the same race that our discrimination kicks in. However, you can train babies not to become tuned into their own race if you keep exposing them to faces from other races.11 So the next time you think that other races all look alike, don’t worry, it isn’t racism – it’s your lack of brain plasticity.