Friday, February 3, 2012

Out Of Siberia - Dogs Not Humans

The endearingly fascinating topic of dog domestication is in the news again. A skull with features that are a mix of wolf and dog was found in the Altai mountains of Siberia. It has been dated to around 33,000 years ago, before the Last Glacial Maximum, a period of intense expansion of polar and mountain ice sheets that began around 26,000 years ago and lasted until around 19,000 years ago.  It may represent an early wolf to dog domestication "in progress", but one that researchers feel was aborted by the advent of the last Glacial Maximum, when human populations in this region dispersed.  There is no evidence in younger deposits from this area of domesticated dogs, despite there being an occasional human presence.

I wrote about this topic some weeks ago and I commented that there probably were many such instances of marginal members of wolf packs getting acculturated to humans and getting self-domesticated or being pushed in that direction by human selection of docile traits. This is after all a meeting between two hyper-social species and contact between wolf and humans would have been a very common occurrence. Another equally old dog skull from a cave in Belgium suggests that there were multiple instances of dog domestication.

What struck me about this latest discovery is the age and the place - 33,000 years ago in the Altai region...... Denisovans??

Modern humans were not the only inhabitants of this region of Siberia.  A  population of another distinct human "species" or variety, descendants of an earlier human migration from Africa about half a million years ago, also lived in this region. Their remains  were found near Denisova cave in the Altai mountains of Siberia and judged to about 41,000 years old.

Its fascinating to speculate on whether there were any instances of wolf domestication in the company of these other human species. The Denisovans  (and the Neanderthals) were human lineages that had a long presence lasting more than one hundred thousand years in Asia and Europe and they would have encountered wolves routinely. We don't know anything about the social and cultural aspects of Denisovan society, but we do know that their cousins the Neanderthals lived in closely knit social groups.

A lot has been said about what the differences may have been between these archaic human groups and "modern" humans. Put forward are differences in cognition (we were just smarter), language and communication skills, division of labor (modern humans had more efficient food gathering strategies),  home range and mobility affecting trade and cooperation with other groups (Neanderthals did not trade as much with other groups). These are all speculative and maybe we can add one more.

These archaic humans did not or were unable to domesticate the wolf. No remains of domestication have been found so far, associated with the Neanderthals. Does the same apply to the Denisovans and other archaic human groups scattered across Africa and Asia?

That off course could be a reflection of something about their behavior as individuals and as a society. Perhaps the wolves themselves stayed away sensing a lack of that bit of empathy, perhaps their hunting methods did not require cooperation with a willing canine partner. If there is evidence for dog domestication or partial domestication about 33,000 years ago, could there be even earlier instances of the dog? And if the timing of dog domestication overlapped with modern human contact with Neanderthals and Denisovans from 45,000 to 30,000 years ago,  did the dog give some advantage to modern humans in eking out a living over these other human "species"?

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