John Woolf asked:
Dear Dr Chris
Has the human brain developed at the same rate as the human body? If you took a human brain of 10,000 years ago and implanted a representative cross-section of today's accumulated knowldege would be able to function as if it were a contemporaneous brain?
Diana - I think, yes, of course. Someone who lived 10,000 years ago would be very capable of understanding all of the problems and issues that we have to deal with today. In fact, around 10,000 years ago, it was when humans were doing really incredible things like developing agriculture which would have taken some intelligence, and doing what essentially is modification of different grains and vegetables, and things which takes some foresight and some planning. And in fact, the anatomically modern human, as it’s known, first appeared 200,000 years ago and there's no evidence to suggest that people then had different brains to the ones that we have now. Although there are some arguments about maybe something happening around 60,000 years ago, but we don’t really know for sure, but it looks like certainly 10,000 years ago, people were just as intelligent as they are now. [But the type of intelligence has probably changed over the last few Millenia because people are exposed to very different problems in their day to day lives.]
Chris - How do we know that the brains of people 200,000 years ago were similar because brain tissue doesn’t fossilise, does it? So how would we know that?
Diana - To be fair, it is a little bit of guesswork. There is genetic evidence to show that anatomically modern humans have – well, we have evolved a little bit. There are a few mutations that have turned up over the last few hundred thousand years, but if you take a fossil of a human and open up the brain case, look inside at the shape and the volume, and the way that all of the little veins and vessels are marked out on the inside of the brain case, it actually doesn’t look very different at all from what we find now.
Chris - So, you're referring to the idea of the sort of endocast idea where the shape of the skull can form a fossil on the inside where the brain would’ve been, leaving an imprint on what the brain must've been like because the brain leaves its own imprint on the inside of the skull.
Diana - Yes, that’s right. Yeah, your brain does imprint in the inside of your skull as you grow up, strangely enough!