For most of human evolution there has been about a 2 million year trend for bigger brains. But in the last 20,000 years there has been quite a reversal on that ancient trend. And I’m not pulling a fast one on you, for a time this was only a known fact among paleoanthropologist, and they notice this trend despite what region of the world or demograph. And when biologists and geneticists learned about this trend they were as surprised as anyone that our specious are loosing grey matter. It does make sense though that anthropologists specifically paleoanthropologists would recognize this trend since they are likely the only field that looks at contemporary human anatomy to millions of year old fossils and skulls.
Based on skeletal analysis of skulls from 20,000 years or before the average volume of someones brain was around 1500cc (cubic centimeters) and today that has dropped to around 1350cc. That’s about the size of a tennis ball! And as I said this trend is happening everywhere, Europe, Asia, Africa you name it. Simply put by anthropologist Christopher Stringer “It’s Strange.” And for now no one really knows why this trend started or whether a smaller brain is inherently bad or will lead to less intelligence. But there are some studies that are trying to understand this trend.
One studied suggest that the development of complex societies lead to a decrease in brain size. As society became more complex and spread the workload there was no need for a big brain to us your wits and try to survive. Civilization became like a social safety net.
One study measured the skulls of Europeans from the Bronze age around 4000 years ago to the medieval times. This research got similar data that as populations increased and society got more complex the trend of smaller brains continued. But the study suggest a smaller but smarter brain. Because a bigger brain takes so much energy to keep functioning, it already takes up about 20% of all calorie intake. So the goal is a smaller but smarter brain. And over the past 20,000 years there have been adaptive mutation related to brain development and neurotransmitter systems that changed the inner working of our brains, but to what extent no one knows. Though they could have affected our temperament and reasoning abilities.
One Study states that it isn’t to do with intelligence but rather the selection against aggression. And that in a way we domesticated ourselves or became more tame. Like all the other animals we have domesticated their brain size has gotten smaller and so more tame than there wild counterpart.
But so far we can only see the changes of our evolution but not where it’s taking us. By anthropologist Stringer “it’s perfectly plausible our modern brain is smarter in some ways, dumber in others, and more docile overall.”
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