Friday, February 11, 2011

What's new with hominid fossils

After Christmas, one of my students brought me a news item he had clipped about some new fossil discovery that would re-write human evolution. Sure it will, I thought. We've all heard that story before. I figured it was just another press exaggeration, but then I read it more carefully. It claimed that researchers had discovered teeth from Homo sapiens in a cave in Israel and that these teeth dated to about 200,000 to 400,000 years ago. Now if that's true, that would be kind of a game changer. Conventional molecular evolution studies put the origin of Homo sapiens at about 150,000 years ago in Africa, so finding Homo sapiens teeth that were twice that old in Israel would be kind of a big deal.

I have to confess that I was cautiously optimistic, probably because I'd like to see more evidence that Homo originated closer to the Middle East than subsaharan Africa. You know, around where Noah's ark landed. I'm kind of biased that way. Technically, since H. erectus is a likely post-Flood human also, finding a 400,000 year old Homo sapiens tooth in Israel wouldn't be that big a deal. H. erectus remains go back to 1.8 million years by conventional dating. But like I said, I was cautiously optimistic.

Anyway, I checked out the original paper, and unfortunately it was yet another case of press hyperbole. The teeth are actually not diagnosably Homo sapiens. The authors suggest that the teeth could be "archaic Homo," Neandertal, or a mix of different taxa. I guess people won't be arguing the "Out of Israel" hypothesis any time soon, but it's still an interesting discovery. Check out Brian Switek's post for a fuller analysis, and look at Hershkovitz et al.'s original paper, which for now can be found in PDF right here.

Meanwhile, this week's Science has a report on an Australopithecus afarensis complete fourth metatarsal that adds yet more evidence of australopith bipedality. To review, evidence for bipedality in australopiths includes the way the skulls connect to the backbone, the shape of the thigh bone and the way that bone connects to the hip and knee, and the famous Laetoli footprints. Now we can add to that evidence from Ward et al. that australopiths had arched feet like ours.

Hershkovitz et al. 2010. Middle pleistocene dental remains from Qesem Cave (Israel). American Journal of Physical Anthropology DOI: 10.1002/ajpa.21446.

Ward et al. 2011. Complete Fourth Metatarsal and Arches in the Foot of Australopithecus afarensis. Science 331:750-753.

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