An extensive dog genetics study at UCLA has returned results that suggest that the Middle East is the birthplace of the domesticated dog as well as of cities and agriculture. Dogs share more DNA with the Middle Eastern gray wolf than with any other wolf population in the world.
Earlier genetic research pointed to dogs having an East Asian origin, but this result was never supported by the archaeological record. Dogs, on the other hand, have been found buried along with humans in the ancient Fertile Crescent.
Previous genetic research had suggested an East Asian origin based on the higher diversity of mitochondrial sequences in East Asia and China than anywhere else in the world. (Mitochondria are tiny cellular structures outside the nucleus that produce energy and have their own small genome.) However, that research was based on only one sequence, a small part of the mitochondrial genome, Wayne noted.
“That research made extrapolations about how the domestic dog has evolved from examination of one region in the mitochondrial genome,” Wayne said. “This new Nature paper is a much more comprehensive analysis because we have analyzed 48,000 markers distributed throughout the nuclear genome to try to conclude where the most likely ancestral population is.
“What we found is much more consistent with the archaeological record,” he said. “We found strong kinship to Middle Eastern gray wolves and, to some extent, European gray wolves — but much less so to any wolves from East Asia. Our findings strongly contradict the conclusions based on earlier mitochondrial DNA sequence data.”
A small group of East Asian dog breeds were found to be genetically related to Chinese wolves, so obviously that means there’s mating between the wolves and dogs, but we don’t know how recent or ancient the interbreeding is.
Another interesting tidbit from the study is that when you map out the relationships between ancient and modern dogs, the structure produced is surprisingly similar to the way dog shows classify dogs by function (herding, sporting, working, etc.). The one exception appears to be the toy dog, whose DNA come from all classes.
“We found there is a surprising genetic structure that accords with functional classifications — suggesting that new breeds are developed from crosses within specific breed groups that share particular traits,” Wayne said. “If they want a new sight hound, they tend to cross sight hounds with each other, and the same with herding dogs and retrieving dogs. That may not seem so surprising, but we had no reason to think beforehand that these groups would be strongly genealogical.
“There are some notable exceptions, such as ‘toy dogs.’ In this grouping, there are many different kinds of lineages represented, including traces of herding dogs and retrievers. When it comes to miniaturizing a dog, breeders start with a larger breed and cross that with a miniature dog to make a dwarfed breed on a new genetic background, causing the mixing of various lineages. It’s a mix-and-match approach for some of these breed groupings. But in other cases, new breeds have been based on combinations of breeds that have specific traits.”