Reyairia wrote:
Humans are incredibly social animals. We can prove this by saying that we're the only animals with eye whites. Why? So we can read each other better.
I have seen a suggestion that humans evolved a white sclera to give better signals for gaze direction. The argument is weakened by the fact that lots of species have a high contrast between pupil and iris or sclera, even if they are not social. Here are examples of some animal eyes:
I can't be sure of identification from just looking at the eye. I
think the picture in the second column, third row from the top shows a frog's eye, the one in the fourth column, bottom row looks like an octopus to me. Not social.
Of course, two counterexamples aren't enough. Your argument would still stand up if high contrast is correlated with living in a social group. I have no idea whether that correlation exists.
Reyairia wrote:
I think that when apes evolved to humans and tried to adapt to places with a high degree of civilization and large populations in small areas
I think you have to change the detail of the argument, because the timing doesn't work out. High population densities and anything resembling civilization have been around only since the invention of agriculture, about 5000 - 10000 years ago in the Fertile Crescent and china and about 2000 years ago in America. Modern humans with their big brains have been around for a lot longer than that, I think it's about 200000 years. But you are right that modern humans, even in hunter gatherer societies, do have larger groups sizes then chimps and bonobos (150 - 250 instead of about 30 - 50). The suggestion that the demands of social life are responsible for humans' big brains is the
social or Machiavellian intelligence hypothesis.
I'll have to listen to the podcast before I can make any more comments.