The most fascinating thing for me in all this is . . .DNA. The general theory is that evolutionary pressure stops at the upper age for reproduction. The vast, vast part of our evolution was in pre-history, so that limit would be at about 40. But then this. Therefore there was evolutionary pressure to make sure that the older folks could still march with the tribe. We increased survival among the youngers who were willing to be taught. We drew the pictures of the beasts to be hunted and we knew what mushrooms were safe to eat. We couldn't kill the beasts but we could carry them home. Etc. I don't see another explanation. Except for what Darwin called "sports", DNA.is quite consistent. It's the way it is for a reason. I think autism is just "sports." We're good enough physically, but we have to get smarter. There's always both nature and nurture.