We were never chimps

It’s natural to turn to our closest living relatives, the great apes (chimpanzees and bonobos, gorillas, orangutans), for insights into what our remote ancestors were like. But the fossil evidence suggests that current great apes aren’t a good guide to our past. Below is a figure from a recent article reconstructing diet and habitat for Morotopithecus and some relatives, from just over 20 million years ago, and later. It looks like all these guys inhabited relatively open woodland – trees interspersed with grass – rather than the closed canopy tropical forest that is the modal habitat for all the living great apes. Also, they may have specialized in consuming more young leaves, and less fruit than, say, chimpanzees. On current evidence, then, our closest living relatives have all evolved away from our common ancestors, to become (not terribly successful) tropical forest specialists.

Also, more on this later: gorilla and chimpanzee knuckle walking may be a poor model for locomotion in our common ancestor. Asking how we evolved from a chimp-like ancestor is probably asking the wrong question. 

Pace Jared Diamond: a good book and a snappy title, but we are not The Third Chimpanzee.