Excerpt from Will Storr's Selfie ...
The self’s ingestion of culture can be tracked, in a startling form, in the brain of a growing baby. Despite the fact we’re born with almost as many neurons as we’ll ever need, the weight of a child’s brain increases by more than 30 percent during its first fifteen months. If this rapid gain isn’t due to the generation of brain cells, then what is it? Most of it is the weight of new connections, or synapses, that are forming between these cells. By the age of two, a human will have generated over a hundred trillion synapses, double that of an adult. So great is this extra brain functionality that youngsters even develop cognitive powers the rest of us lack. Six-month-olds can recognize the faces of individuals from other races with an ease that would have the rest of us worrying quietly whether we are racist. They can even readily identify monkey faces. Babies can hear tones in foreign languages that their parents are deaf to. They’re also thought to experience synaesthesia, the eerie blending of the senses that enables people to taste colors, and so on.
But then begins the cull. These connections start dying off at a rate of up to 100,000 per second. It’s believed that this is one of the ways the brain shapes itself to its environment. Huge connectivity means it’s prepared to deal with a wide range of potential possibilities. Then, when connections between neurons are not activated, they’re killed. They call this “neural pruning,” and it works a little like a sculptor carving a face out of a block of marble: it’s what’s taken away, as much as what is added, that makes us who we are.
When we’re born, then, our brain is ready for the world – or at least a world. It rushes out to greet it, gets to know it, then prunes itself down, specializing itself for the particular cultures in which it finds itself. …
In a major study, researchers in Queensland collated the results of 2,748 papers and concluded the average variation across all human traits and diseases is caused by 49 percent genetic factors and 51 percent environmental factors. ….
“…. We’ve come to realize that it’s much more complex than just being a dollop of genetics and a squirt of environment.” The relationship is symbiotic. Nature and nurture are not in competition, but in conspiracy.
from pp. 55-6 of Will Storr’s Selfie: How we became so self-obsessed and what it’s doing to us
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