Anyway on the episode of What Makes us Human that I saw, they talked about ASPM gene, which they say is a gene that may related to our brain size.
Further it seems that the Gene went through a change or 'upgrade' about the same time humans started doing agriculture and starting to live in larger more permanent settlements (e.g. towns). This gene started to be replicated in our species quickly and today about:
- 10% of us have 2 of the new version ASPM genes
- 40% have one each
- 50% have just the old
So then they suggest that the reason it was "naturally selected" is that it made us smarter.
Morons, if it showed up when we started to live in larger groups it could be related to anti-social behavior, change in health issues due to a new life style (not hunter gatherer), or just plain being annoying!
Smarter, bah, I bet the smart humans have at least one old gene!