Mankind, being naked and without fur, had to have risen in a temperate region rich in food and water with few predators; what happened after that doesn't matter a hill of beans compared to what modern man decides for the future.
We must now still live in accomodating circumstances if we have this many people rewriting our history every time they get a research grant.
Let's fix the ozone hole, global warming, poverty, establish world peace and figure out how to run our cars on sunbeams before we are forced to start the whole process over.
There are other planets to conquer.
Maybe that paradise turned cold over thousands of years and it was a slow process of adaption.