I have read that we have not altered much in about 12 thousand years..including our brains.. Due to not many people having a education (apart from there trade) . I just think we are using the same amount of brain power (or capacity).. we just gotten the opportunity to use it (over how many thousands of years)..not just the elite few. I have heard the stuff about us and living in nature.. i think i have read that because we took up most of our time selfishly or just within a small tribe.. we did not realy care about the 'bigger questions' of life the universe etc.. We did not have burdensome ethics/morales/beliefs to impinge our thinking so we essentialy were more happy with our selves..I think we have 'evolved' more than any of those people could imagine. If its a good or bad thing i don't know...i can't complain
Humans do suffer from more genetic diseases than other species according to this: http://www.newscientist.com/article.ns?id=dn6920
im not saying animals are better than humans, but realistically humans cause the most damage to the earth than any other species