It’s a big day for the evolution of our species! Tomorrow’s issue of Science contains 11 – yes eleven – papers describing the fossil skeleton of Ardipithecus ramidus, a hominid from 4.4 million years ago – the oldest such fossil ever found. As I write, the articles aren’t on line yet (and will probably require a subscription to read them completely), but the BBC and The Guardian both have substantial pieces on the discovery.
Briefly, a partial skeleton has been found of one female, together with bits and bobs of another 30 or so individuals,in Ethiopia. “Ardi”, as the female has been called, was about the same size and weight as a modern chimpanzee, but looked very different – many components (such as its hand) are more primitive than that of a chimpanzee,. This shows that the modern chimp hand is not the ancestral condition, but rather a highly evolved form.
Amazingly, the fossils were first found in the early 1990s, and it has taken 17 years to fully investigate them. It appears that Ardi could climb, but also walked on her knuckles [EDIT: no, she didn’t – she was BIPEDAL; mea culpa, and thanks to posters for pointing this out] walked on both legs; she ate fruit, plants and small mammals. Neither the males nor females had large canines – like us, but not like chimps. This suggests that strong male-male competition, which occurs in chimps, did not occur in our common ancestor.
However, despite the hype that will inevitably surround this amazing discovery (surely much more justified than the hoo-haa over Ida, the 47my old primate fossil), Ardi was not that common ancestor. Unfortunately, The Guardian calls her “our long lost mother”, but it is not yet clear exactly where she fits into our family tree. She may be an ancestor of Australopithecus – the species to which “Lucy” belonged.
The Guardian has this video snippet describing the discovery (upcoming from the Science website, I think) and this 10 minute MP3 file in which Tim White describes the link between Ardipthecus and the link with our last common ancestor with chimpanzees.
Now here’s a question – how will the creationists get out of this one?