Verified by 
It is becoming increasingly clear that the separation of dogs from wolves is a process that began tens of thousands of years ago and remains incomplete because wolves and dogs continue to hybridize wherever they can mate freely. The cross-fertilization is usually discussed in terms of dogs but, in fact, it flows both ways, with wild wolves carrying dog genes and dogs carrying wild wolf genes. This topic is not one many dog researchers or wildlife biologists like to discuss, raised as they are on the verity that species are distinct reproductive units and nothing good or enduring comes of their rare unions, especially those between wild and domestic animals.
A new paper, “Gene Flow Between Wolf and Shepherd Dog Populations in Georgia (Caucasus)”[abstract available for free], by Natia Kopaliani, Maia Shakarashvili, Zureb Gurielliidze, Tamar Qurkhuli, and David Tarkhnishvili, of the Institute of Ecology, Llia State University, Tbilisi, Georgia, published online on March 12, 2014, in the Journal of Heredity clearly shows that the famous Caucasus sheep guarding dogs, the large, fierce dogs that are considered among the most effective in the world at their task, have for thousands of years hybridized with wolves. The researchers examined mitochondrial haplotypes and microsatellite genotypes from 102 wolves, 57 livestock guarding dogs, and 9 mongrel dogs from the Caucasus, a region where wolves and dogs, shepherds and sheep still follow traditional patterns of transhumance.
A Caucasus shepherd dog. Photo ©Natia Kopaliani.
“Most of the studied dogs had mitochondrial haplotypes clustered with presumably [my emphasis] East Asia dog lineages, and most of the studied wolves had haplotypes clustered with European wolves, but 20 percent of wolves and 37 percent of dogs shared the same haplotype,” the researchers said. (Haplotypes are long stretches of chromosomes or even whole chromosomes that, inherited together, suggest shared ancestry.)
Looking more closely, the researchers found that more than 13 percent of wolves and 10 percent of dogs had readily discernable dog or wolf ancestry respectively. At least 2 to 3 percent were identifiable as first generation hybrids.
The researchers suggest that this high level of crossbreeding has had a significant effect on the genomes of dogs and wolves. Their findings reinforce a proposal by other researchers that at least some haplotypes identified by dog geneticist Peter Savolainen as being from East Asian dogs, which includes virtually all of those found in modern dogs, are, rather, from western European wolves and reflect a significant contribution to development of the dog in areas like the Caucasus.
For example, 14 percent of wolves and 17 percent of Caucasus shepherd dogs have the same haplotype from clade B, one of the groups showing the maternal ancestor and all of her descendants, as determined by mitochondrial DNA, into which researchers have divided dogs. The authors of this study argue that their findings support the view that CladeB, far from being of East Asian origin, represents a lineage that passed from European wolves to dogs. It must have originated with European wolves and passed from them to dogs because it is not found in Asian wolves.\
the genes flowed both ways and reflect matings of male wolves and female dogs, as well as female wolves and male dogs, believed the more common pairing. The authors point out that shepherds would breed captive male wolves with female dogs in order to reinvigorate their line of dogs.
I used to think that the arrival of animal husbandry created the chasm between dogs and wolves, but the suggestion here is that hybridization was common from the appearance of the first dogs and continues to this day in areas where wolves are common and livestock dogs are still used in traditional ways. The researchers identify those areas as Anatolia, mountainous parts of Iran and Iraq, Turkmenistan, and the Caucasus. The limiting factors are the number of wolves and freedom to roam of the dog population.
Combined with other recent studies showing that dogs emerged in hunting and gathering societies and continued to crossbreed with wolves for a considerable time, this study helps consign to the cabinet of failed ideas, Raymond Coppinger’s theory that dogs arose from a population of wolves who scavenged the garbage dumps of early agriculturalists and in so doing tamed themselves so that they wanted only to seek attention and affection from humans. (Coppinger’s theories are laid out in considerable detail in his 2001 book, co-authored with his wife, Lorna, Dogs: A Startling New Understanding of Canine Origin, Behavior, and Evolution. See Marc Bekoff's review here.)
In the process of domesticating themselves, he says, those wolves became juvenilized in appearance and behavior. (The retention of juvenile traits into adulthood is known as neoteny.) That transformation was necessary, he says, because wild wolves are nearly impossible to socialize and train.
Among the most juvenilized dogs are livestock guards, Coppinger says. Because they can be so gentle with the sheep under their watch, he says they could be neither wolf nor wolf hybrid. But according to the authors of this new paper, here they are not only in the Caucasus but also wherever wolves and livestock guarding dogs are still abundant and allowed to mix as they always have.
With crossbreeding so commonplace how did that separate or different entity the dog emerge? We may never have a completely satisfactory answer, but it is becoming increasingly apparent that the question is not how many centers for early dogs were there but why did some dogwolves (a name I use to distinguish doglike wolves from wolflike dogs or wolfdogs) make the leap to doghood while others did not? Might the answer lie in the type of mutations that occurred among ancient populations of dogwolves that became isolated from a larger population of wolves and were forced by circumstances to engage in unwelcome levels of inbreeding that would capture specific mutations, what canid geneticists Robert Wayne and Bridgett vonHoldt have called discrete mutations with large effects [article available for a fee], like the mutation for smallness itself. Among the least visible of those changes might well have been an extension of the critical socialization period that allowed dogs to bond more readily to other species.
Since the rise of scientific breeding in the late 18th century domestication of the dog has been under way in earnest. (Many geneticists date this event to 100 to 150 years ago and the rise of kennel clubs, but I think the earlier date more accurately reflects the rise of scientific breeding.) Humans began closing bloodlines to other types of dogs and certainly to wolves.
Breed purity became the watchword, a transformation nearly coincident with efforts to exterminate wolves across much of their former range.
Dogs have increased in numbers exponentially, but whether they have benefitted from being forced, in the process of breed formation, into restrictive genetic bottlenecks is another question entirely, and one many of us do not want to face.
