"When our ape ancestors moved -- for reasons unknown -- onto the open, relatively treeless savannah, they left behind the rain forest and its abundance of fruit and leaves, the mainstays of modern chimpanzee diets."
Yes, that's what I would have done, left my warm place, full of food source and protection To live in a cold, treeless barren place, before my ability to think, reason, eat and digest these things "evolved".