New situations lead to greater change
The move made so long ago by the early primates from a ground-based scent-dominated often nocturnal existence, to a life in the trees, led to the development of grasping hands, long arms, stereoscopic colour vision an increased brain size. With the aid of these talents, the monkeys and ape have made a great success of their arboreal life. But those of them that subsequently returned to the ground, whether it was because of an increase in body size or some other reason, found that these very talents could be deployed in their new situation in a manner that opened up fresh possibilities and led to further changes. The enlarged brain led to an increase in learning and the beginnings of a group culture; the manipulative hand and the coordinated eyes made possible the use and manufacture of tools. The primates that are practising these skills today, however, are in essence repeating a process that another branch of their family started soon after the ancestral apes first appeared in Africa. It was this branch that eventually stood upright and developed their talents to such a degree that they came to dominate and exploit the world in a way that no animal had ever done before.