The pygmy chimp as hominin prototype? The proportions of bonobos might instead suggest specialised quadropedalism featuring horizontal posture: low intermembral index, short clavicle, narrow trunk and reduced iliac breadth all approximate more terrestrial monkeys but not swinging monkeys. (Bipedalism would favour a wider ilium.) Still Ardipithecus had plantigrade hands like monkeys and Proconsul. Our hands resemble a monkey's not one of the other apes. The inner ear of Stw 53 suggests a horizontal posture(!) for Homo gautengensis.



What the hell, something else from the archives. So much for plans to publish new stuff (such as the long-awaited take on the recent Dinosaur Art event, and on the book). Anyway, the article here first appeared on Tet Zoo ver 2 in November 2009 and resulted in quite a few comments. I’ve made no effort to update it, sorry.

Produced by Adrienne Zihlman, the picture shown here has been used to support Zihlman’s ‘pygmy chimpanzee hypothesis’ (Zihlman et al. 1978): this being the idea that the Bonobo Pan paniscus is “the best prototype for the common ancestor of humans and [other] African apes” (Zihlman 1984, p. 39).

Many recent discoveries have shown that at least some australopithecines really were more chimp-like than used to be thought, and the old idea that fossil hominins were just prototype versions of Homo is now very much dead. However, fossils like Sahelanthropus and Ardipithecus have also highlighted the fact that chimps, bonobos and other modern great apes are anatomically specialised too (e.g., Lovejoy et al. 2009), and are not relicts that necessarily reflect an ‘ancestral’ morphology.

So… is the ‘pygmy chimpanzee hypothesis’ still viable, or is it defunct? One doesn’t see it getting much discussion these days, and the proposal that fossil African hominids were closely similar to the bonobo in proportions and so on has not been supported; so I think it is no more. But, hey, I’m no palaeoanthropologist.
http://blogs.scientificamerican.com/...ee-hypothesis/