wolves

A new paper by Anna Druzhkova and colleagues examines the ancient mtDNA sequence of a putative 33,000-year-old dog from Razboinichya Cave in the Altai region: "Ancient DNA Analysis Affirms the Canid from Altai as a Primitive Dog" [1]. The paper's analysis is a simple application of phylogeography, showing that the mtDNA of the Altai dog fits in a clade with a number of pre-Columbian New World dogs:

The domestication of dogs from the grey wolf is well accepted [1]. However, the timing, location and number of domestication events is still actively debated [2]–[5]. The archaeological record provides unequivocal dog remains beginning about 14,000 calendar years (cy) ago [6]–[7] requiring a domestication that predates agriculture. Putative dog remains ranging in age from 31,000 to 36,000 cy [2] [8]–[9] have been questioned as potentially representing aborted attempts at domestication, or morphologically unique wolves [4]. A full mitochondrial genome analysis of modern dogs suggests an origin in southern China around 16,000 years ago [10], whereas an extensive nuclear genome-wide SNP analysis supports a Middle East and European origin [11], which is more in accordance with archaeological data. Here we isolated, sequenced and analysed 413 nucleotides of the mitochondrial DNA control region from a putative dog specimen dated as approx. 33,000 cy from the Altai Mountains in central Asia. Only a single specimen - namely the Goyet dog (36,000 cy [2]) predates the Altai dog and hence it is thus far the second oldest known specimen assigned morphologically to the domestic dog [8].

The evidence of dog domestication has developed piecewise over the last several years. A number of Upper Paleolithic skeletal specimens have morphological dimensions inconsistent with wolves, but comparisons of the genetics of recent dogs has tended to argue against such early domestication.

In the current paper, the mtDNA similarity of the Razboinichya canid and pre-Columbian American dogs is pretty persuasive evidence that this specimen came from an early population ancestral to the dogs of northeast Asia, which would later enter the New World. This paleontological specimen shows that the mtDNA phylogeny of modern-day dogs does go way back into the Late Pleistocene, which argues against a single recent domestication. Still, the mtDNA is not the strongest possible source of evidence, since present-day dogs can be found across many of the clades that include mtDNA from wild wolf populations.

Curiously, Druzhkova and colleagues did not include the Goyet canids in their mtDNA comparisons. An analysis of 57-bp of the mtDNA of these dogs was carried out by Germonpré and colleagues [2], showing that the Belgian Upper Paleolithic dogs have a diverse range of mtDNA haplotypes, across several clades of the wolf genealogy. The current paper bases its mtDNA cladogram on 400-bp sequences, so they aren't strictly comparable, but it is nevertheless interesting that the other putative early dogs are not part of this clade including pre-Columbian dogs and the Altai specimen.

The earlier description of the Razboinichya canid by Ovodov and colleagues [3] suggested that the specimen was part of an early domestication event that was "arrested" by the Last Glacial Maximum.

We suggest that the pre-LGM Goyet and Razboinichya canids are unlikely to be the ancestors of post-LGM dogs. These canids most probably are both “proto” or incipient dogs that did not persist long enough to found enduring lineages, since no putative dog remains have been found at adjacent sites in western and central Europe and in Siberia occupied during the LGM. The ecological changes caused by progressive cooling almost certainly caused social and settlement pattern changes severe enough to have disrupted the domestication process and prevented the evolution of fully domesticated dogs.

Such a scenario would reconcile the early skeletal evidence for dogs with the conclusion that recent dogs come from a small mtDNA population.

But I think it's too soon to conclude that today's dogs don't have deeper Pleistocene roots. As zooarchaeologists have been finding more and more possible evidence of dogs, they may be filling in the record (for example, with apparent dogs from the Gravettian Předmostí site [4] and from the later Upper Paleolithic of Kesslerloch, Switzerland [5]). I wonder whether a good actualistic study of dog deaths and remains in small-scale human societies would give rise to clearer expectations about how many dog skeletal specimens we should expect from Upper Paleolithic contexts.

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