Friday, November 11, 2016

New research on Homo naledi


It's been a while since we heard anything about Homo naledi, but the researchers have been busy.  In case you missed it, here's a brief rundown of some recent research.

First up, in a surprisingly speculative paper in the South African Journal of Science, Wits professor Francis Thackeray proposed that the bones of H. naledi had lichen stains on them from exposure to light. If correct, the resting of the bones on the surface would imply that the bodies of H. naledi were not intentionally deposited in the Dinaledi chamber but just fell in there.  I say this was speculative, since Thackeray's argument (as I understood it) was based on visual similarity of some stains on the bones to stains on some rocks that might have been made by lichens.

The response by Randolph-Quinney and colleagues provides a nice overview of the deposition of the bones as well as a small update on recent work (such as what kind of invertebrates are living in the cave).  The authors note that the stains are on all sides of the bone, which would not be consistent with lichen growth, and some of the stains clearly indicate a soil/air interface.  So no dice on the "lichen stain" idea.  The staining is not consistent with the bones being exposed to lichens and sunlight.

This week, we got two new papers on the bones themselves.  In the first, Schroeder and colleagues examine the shape of the Homo naledi skull.  They find that it is most similar to members of Homo erectus, which is not terribly surprising.  In the second, Feuerriegel and colleagues describe the arms of Homo naledi.  Their description elaborates on details previously mentioned in the main description.  We see again that the shoulder of Homo naledi is very different from our own shoulders and more like a baboon shoulder.  This could imply that the arms of Homo naledi are built for climbing.

Finally, Lee Berger was in London this week giving a presentation.  Paul Garner tells me that we can expect a date for the fossils in the first quarter of 2017.  Apparently, it will be a surprising date.  So I'm guessing it's not actually "early" Homo, which would need a conventional date of around two million years. Something much more recent perhaps?  I guess we'll find out.

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