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More Evidence that Dogs Rose Early On

Ancient wolf genome points to dog divergence at least 27,000 years ago

The June 1, 2015, of the journal Current Biology (the article is available here) reports on the sequencing by Swedish researchers of the genome of a Pleistocene wolf who roamed the Taimyr Peninsula of Northern Siberia some 35,000 years ago and belonged to a population of wolves who split from the common ancestor of modern gray wolves and dogs “at least 27,000 years ago.” That firmly fixes emergence of the dog before the Last Glacial Maximum when early modern humans still lived in bands as hunters and foragers.

Using radiocarbon dating to obtain a relatively precise age of their specimen, named Taimyr 1, the researchers used its fully sequenced genome to recalculate the rate of genetic mutation in dogs and wolves and found it to be slower than previously assumed. In recalibrating the molecular clock, they assumed a three-year generation time rather than the two years often used by other researchers. When applied to previous studies showing more recent divergence of dogs and wolves, which relied on faster mutation rates, the recalibration produces dramatically different results. Thus, the Swedish geneticists recalculated the timing of the divergence of dogs and wolves published in a paper in 2014 in PLoS Genetics as 11,000 to 16,000 years ago, and it became 27,000 to 40,000 years ago.

Lead author Pontus Skoglund of Harvard medical school and the Broad Institute of Harvard and MIT writes that the team’s findings bolster the hypothesis that “the ancestry of present-day dogs is derived from multiple, regional wolf populations, through crossbreeding that in some places has continued into the present (see, for example, my earlier blog post). “In “northern latitudes,” according to Skoglund, early dogs mated with the now extinct Taimyr wolves, whose genetic material continues to exist in Siberian huskies and Greenland sledge dogs.

Combined with the work of Olaf Thalmann and an international team of canine geneticists published in Science in 2013 (abstract available here), this research should put an end to persistent claims that dogs originated from self-taming wolves feasting on the garbage heaps of Mesolithic humans beginning to settle into permanent villages as agriculturalists. (As a thought problem: If the wolf is “tame” enough to approach the settlement and eat the garbage, why would natural selection have to work to make its descendants more tame or docile? Modern dump-diving wolves in Italy and Israel have not become dogs or more doglike.)

In How the Dog Became the Dog, I suggested that given their similarities in terms of social structure and propensity for and skill at cooperative hunting, as well as their apparent natural affinity for each other, it was possible that early modern humans and wolves formed alliances wherever they met on the trail of the Pleistocene megafauna they were hunting. In fact, the ethologist Wolfgang Schleidt has suggested that wolves taught humans how to hunt cooperatively.

Not all meetings between humans and wolves need to have produced dogs or even tame wolves. In fact, most probably did not. Even where dogs did exist, in places where their numbers were low—or local wolves were not numerous—crossbreeding could have kept dogs and/or wolves alive. People traveling with dogs would have facilitated, if inadvertently, their admixture at trading hubs and other places where bands gathered. In any event, these were hunter-gatherers, not proto-farmers.

Paleoanthropologist Pat Shipman has argued in her recent book, The Invaders, that early modern humans teamed with early dogs to contribute to the demise of Neanderthal, around 40,000 years ago. Without fully accepting her argument, it is easy to envision how dogs extended the reach of human hunters by finding and tracking prey, carrying provisions, guarding camps and serving as companions, not to mention emergency meals.

That is right at the date that Skoglund and his collaborators put as the outer-limit for the divergence of grey wolves and dogs, but in archaeology most dates involving human and dog evolution change by growing older.

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