Thursday, October 01, 2009


The panthropologists need to explain Ardi. It's not that Ardi can't be explained by any possible panthropology, but the fossil evidence must be dealt with, which in this case means, among other things, dealing with an affirmation of great diversity among the hominoidea, hominidea, and to put a fine point on it, the hominini. Check out Nature's report on the unveiling of the oldest hominid fossil, Ardipithecus ramidus. Key takeaway: "humans did not evolve from ancient knuckle-walking chimpanzees, as has long been believed. The reports, in Science, illuminate how early phases of humans evolved along a separate lineage from the last common ancestor shared by early hominids and extinct apes."

The news staff at Scientific Blogging also stresses this point:

Until now, researchers have generally assumed that chimpanzees, gorillas and other modern African apes have retained many of the traits of the last ancestor they shared with humans—in other words, this presumed ancestor was thought to be much more chimpanzee-like than human-like. For example, it would have been adapted for swinging and hanging from tree branches, and perhaps walked on its knuckles while on the ground.

Ardipithecus challenges these assumptions, however. These hominids appear to have lived in a woodland environment, where they climbed on all fours along tree branches—as some of the Miocene primates did—and walked, upright, on two legs, while on the ground. They do not appear to have been knuckle-walkers, or to have spent much time swinging and hanging from tree-branches, especially as chimps do. Overall, the findings suggest that hominids and African apes have each followed different evolutionary pathways, and we can no longer consider chimps as "proxies" for our last common ancestor.

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posted by Fido the Yak at 10:22 AM.


Anonymous Anonymous said...

Interesting. I haven't read much gould but I've always wondered how often one species turns into another one.
Apparently the fossil record is rather 'jumpy' - as if creatures almost came out of nowhere.

October 01, 2009 12:58 PM  
Blogger Fido the Yak said...

I should read more about speciation events. They do seem sudden to me, but if everybody accepted some version of punctuated equilibrium theory I would look pretty hard for evidence of gradualism just to be on the side of double plus highly probable.

October 01, 2009 1:13 PM  
Anonymous Anonymous said...

I can see creationists picking up on this pronto. 'we didn't come from ch

October 01, 2009 3:52 PM  
Blogger Fido the Yak said...

I don't have very high expectations of creationists. Paleoanthropologists, on the other hand.... As much as I like chimpanzees, some of the more popular origin stories drive me around the bend. It's gratifying now to see strong evidence that some primitive traits of our clade aren't shared with Pan, because you could deduce as much (in the abstract) starting from an appreciation of the diversity of the hominoids. Now the people who thought you had to make a choice between paniscus or troglodytes—as if—ought to be eating some crow. Pan is no more primitive than any other ape, and in certain respects less so than Homo. But now I'm going out on a limb, dontcha know. I can't quite explain postcranial similarities between Gorilla and Pan. It's probably best to admit I don't know very much.

October 01, 2009 4:55 PM  
Blogger Fido the Yak said...

I have access to the full text articles in Science, btw.

October 01, 2009 5:01 PM  
Blogger Luddhunter said...

Ayn Rand's voice is channeled from beyond to refute a creationist who thinks Ardipithecus disproves Darwin.

October 01, 2009 11:39 PM  
Blogger Fido the Yak said...

Enjoyed Brian Switek's coverage. Must note that he already ran story earlier this year on hypothetical independent evolution of gorilla and chimp knuckle-walking. ("It cannot be assumed that the earliest hominins evolved from an ancestor that knuckle-walked on the ground, and the differences in the knuckle-walking traits in gorillas and chimpanzees suggests that it could have independently evolved in each lineage.") Hmm.

Saw de Waal's piece for the Wall Street Journal. Nice mustering of evidence from gorillas to go with the bonobo data, though I still see characteristic great behavioural diversity (and plasticity) among hominoids.

October 02, 2009 10:08 PM  

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