I got a very interesting book for Christmas called The Case Agaist Reality. It is a short, dense work of philosophy that I am slowly working my way through. Something I just came across in the book has to do with the shrinking of the human brain over the past 20,000 years. Indeed, some apparently argue this shrinking began as much as 100,00 years ago. This was news to me.

Apparently, according to some thinkers, as societies arose and became more complex, our ancestors increasingly didn’t need to ‘know everything’ to survive. They could become specialists. This is an obvious idea to me from a cultural and economic standpoint, but I didn’t realize it has had an impact on our brain size and the ratio of brain size to body mass.

The idea is that Individuals who may not have survived alone or in small groups, could survive in larger, more complex communities. Indeed, culture acts as a sort of buffer, or safety net. Tools, stored food, medical expertise, shared memories (and eventually writing); these all help carry the cognitive burden for people allowing for leaner biological cognition without losing ‘intelligence.’ At the same time, selection pressures decreased, as one could get away with not being an outstanding generalist. At the end of the day, it appears complex societies didn’t make humans dumber; they changed which kinds of minds could survive.

These ideas are still controversial and there doesn’t seem to be consensus. The fact that our brains have been shrinking however doesn’t seem to be in doubt.