After considerable sleuthing, a group of Scandinavian researchers has identified 122 genes at 36 locations on dog and wolf genomes that they believe might account for the most pronounced differences in appearance and behavior between the close cousins. The majority of the genes appear involved in brain development, in reproduction, in digestion of starches, and in metabolism of fatty acids, the researchers reported in the January 23, 2013, on-line edition of the journal Nature. Having found the genes, the group, headed by Kerstin Lindblad-Toh, a geneticist at the Broad Institute of MIT and Harvard who led the effort to sequence the dog genome, then speculated that changes in them played a central role in the emergence of the dog. (Here is a link to the free Nature News article on the paper, which costs money without a subscription.)
At that point, the paper begins to spiral out of control, as its authors, Lidblad-Toh and Erik Axelsson of Uppsala University, strive to make their findings fit a particular theory of dog domestication that lies at variance with most of what is known about the still poorly understood subject. They even directly contradict, without any notice, a paper published last year in Proceedings of the National Academy of Sciencewith Greger Larson of Durham University, Engalnd, as primary author and Lindblad-Toh as senior author.
Mutations in genes affecting the brain influenced behavior, Axelsson, Lindblad-Toh, and their colleagues argue in the Nature paper, making the new dog more docile and less aggressive, more like juvenile than adult wolves.
The researchers claims that they became that way as a result of feeding off the middens, the dumps of people settling into semi-permanent villages on the eve of the Agricultural Revolution some 10,000 years ago. The argument is that doglike wolves , whom I call “dogwolves,” were able to exploit this new niche because of the genetic changes that made it possible for them to digest the grains and cereals humans were beginning to cultivate. The researchers identified six sites holding eleven genes they believe are involved in that adaptation.
Here at last, the researchers conclude, is genetic proof that early dogs emerged from a population of self-domesticating dump-diving wolves. It is a bold statement that garnered headlines around the world.
It was also greeted with skepticism because tidy though the narrative might be, almost nothing about it matches what is known, much less what is generally suspected about early dogs.
By every genetic and archaeological measure, wolves became dogs in the company of hunting and gathering people at least thousands of years before the advent of agriculture. There simply is no way around that.
In trying to bolster their theory, the researchers overlooked recent research showing that in Russia, the Czech Republic and Italy wild barley, wheat and other grains, grasses and roots were being consumed by human foragers as long as 30,000 years ago. Along the shore of the Sea of Galilee, humans harvested wild grains and grasses more than 20,000 years ago. Even Neanderthal got into the act. We can only surmise that additional sites where people were doing will be discovered. It is easier to imagine people feeding cooked grains to the dogwolves among them, and some of those animals developing the ability to digest those starches, than it is to rewrite the past to match a theory of the dog’s origins for which there is scant concrete support.
But all of that requires more research.
I was part of a discussion on this topic with Greger Larson of Durham University, England, on NPR’s Science Friday, January 25. 2013.