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Monday, October 26, 2009

Primatologists Go Ape Over "Ardi"

Today on Science's Origins blog, I report on the first public debate over the significance of Ardipithecus ramidus, the candidate human ancestor and subject of a detailed series of reports--covering 108 pages--in the 2 October issue of Science. In a nutshell, primatologists are taking issue with the "Ardi" team's contention that chimpanzees are no longer good models for the last common ancestor between that species and our own, Homo sapiens, which went their separate evolutionary ways at least 5 million years ago. The debate unfolded at a meeting last week of the Royal Society in London, entitled "The First 4 Million Years of Human Evolution," at which yours truly was in attendance.

Give it a read, you'll be glad you did (and if you have any questions you can ask them in the Comments section of this blog.)

5 comments:

Anne Gilbert said...

"Ardi" is one of the most significant paleoanthropological finds, ever. At leat that's what I think. But now I'm wondering. I never, ever thought humans were "descended from chimps", though, until the Ardi find was published, I had kind of assumed that whoever the ancester was, it was chimp-like. But this is ievidently not the case. However, if the pictures are anything to go by, "Ardi" was certainly "apish": she had opposable toes along with opposable thumbs, and the thumbs were shorter than modern human thumbs, and more like, well, chimp thumbs. So if the putative ancestor of us all wasn't chimplike, I wnodner now, what it was like?

jqb said...

It was Ardi-like, as are we in some respects and as are chimps in some respects.

Ann Gibbons said...

Chimp-like doesn't equal ape-like. In some features, Ardi resembles earlier apes that lived in the Miocene epoch, 8 million to 20 million years ago. In other ways, she looks like no other ape--with traits that link her to later humans. There are many ways to be a hominid (or an ape)--think of the different types of monkeys out there. So, the point of White's and Lovejoy's papers is that just because our closest living relatives are chimpanzees, it doesn't mean that the last common ancestor we shared with them looked like a chimpanzee--they also have been evolving for millions of years...

Michael Balter said...

Thanks to Ann Gibbons, Science's resident expert on early hominins (she knows plenty about later ones too.) Be sure to read Ann's book, The First Human (see her link for details) which tells all about the search for our earliest ancestors, including Ardi.

Anne Gilbert said...

Michael, Ann Gibbons, and all:

Thank you for all your thoughtful replies. What I said was, that I never thought that humans were "descended from chimps", but rather -- at one time, at least -- I assumed they were descended from some apparently chimplike common ancestor. The work on Ardi suggests that this supposition was wrong, because Ardi,even if you don't know much about primates(and I have to admit I don't), she certainly isn't "chimplike", whatever else she may have been. So I wasn't really saying that the ancestor had to look like a chimp, just that it had to recognizably look like an ape(never mind what kind of ape! This is what I would be interested in having answered(what sort of ape the common ancestor might have been, whether or not it resembled any living representative of the great apes).
Anne G