Syndicate content

Most Domesticated Dogs Originated in Middle East, Study Suggests

Most domesticated dogs likely originated from gray wolves in the Middle East, with only some possibly originating in Europe or Asia, according to a new genetic analysis by an international team of scientists led by UCLA biologists. The team reported genetic data from 912 dogs from 85 breeds (including all the major ones) and 225 wild gray wolves (the ancestor of domesticated dogs) worldwide, including populations from North America, Europe, the Middle East and East Asia. The scientists used molecular genetic techniques to analyze more than 48,000 genetic markers (SNPs) on a genome-wide basis in the dogs and wolves. The team has not yet pinpointed a specific location of origin in the Middle East. The new research results were published online on March 17, 2010 in Nature. In their work, the researchers found evidence for certain candidate genes that might have been important in the early domestication of dogs. There was evidence of positive selection for two SNPs located near genes associated with memory formation and/or behavioral sensitization in mouse or human studies. There was also evidence of positive selection for a third SNP that is located near the dog counterpart of the gene associated with Williams-Beuren syndrome in humans. This syndrome is characterized by social traits such as exceptional gregariousness. The current results were consistent with earlier analyses suggesting that three groups of ancient breeds (origins >500 years ago) are distinct from modern domestic dogs that are the products of the controlled breeding practices of the Victorian era (circa 1830-1900). These ancient breeds consist of an Asian group (dingo, New Guinea singing dog, chow chow, Akita, and Chinese Shar Pei), a Middle Eastern group (Afghan hound and saluki), and a northern group (Alaskan malamute and Siberian husky). The current data further suggested that the basenji, a breed of Middle Eastern origin that is in a group of its own, is one of the most ancient of existing dog breeds.

With regard to the Middle Eastern origins of most domesticated dogs, senior author Dr. Robert Wayne of UCLA said, "Dogs seem to share more genetic similarity with Middle Eastern gray wolves than with any other wolf population worldwide. Genome-wide analysis now directly suggests a Middle East origin for modern dogs. We have found that a dominant proportion of modern dogs' ancestry derives from Middle Eastern wolves, and this finding is consistent with the hypothesis that dogs originated in the Middle East. This is the same area where domestic cats and many of our livestock originated and where agriculture first developed," Dr. Wayne noted.

Previous genetic research had suggested an East Asian origin for dogs, "which was unexpected," Dr. Wayne said, "because there was never a hint in the archaeological record that dogs evolved there.”

The archeological record has identified the earliest dog remains in Belgium (31,000 years ago), in the Bryard region in western Russia (15,000 years ago), and in the Middle East (12,000 years ago).

The earlier research suggesting the East Asian origin was based on the higher diversity of dog mitochondrial sequences in East Asia and China than anywhere else in the world. However, that research was based on only one sequence, that of a small part of the mitochondrial genome, Dr. Wayne noted.

"That research made extrapolations about how the domestic dog has evolved from examination of one region in the mitochondrial genome," Dr. 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."

“We were able to study a broader sampling of wolves globally than has ever been done before, including Middle Eastern wolves," said the paper's lead author, Bridgett vonHoldt, a UCLA graduate student in Dr. Wayne's laboratory, who studies the genetics of dog domestication. "In our analysis of the entire genome, we found that dogs share more unique markers with Middle Eastern wolves than with East Asian wolves. We used a genome-wide approach, which avoids the bias of [using a] single genome region."

According to a March 17, 2010 New York Times article by Nicholas Wade, opinions vary on the new research claiming a Middle Eastern origin for most domesticated dogs.

In his article, Mr. Wade wrote the following. “The [lead] author of the [earlier] survey, Peter Savolainen of the Royal Institute of Technology in Stockholm, said he was not convinced by the new report for several reasons, including that it did not sample dogs in East Asia from south of the Yangtze, the region where the diversity of mitochondrial DNA is highest. Also archaeologists in China have been less interested in distinguishing dog and wolf remains, he said.”

“Two other experts on dog genetics, Carlos Driscoll and Stephen O’Brien, of the National Cancer Institute, said they believed that Dr. Wayne’s team had made a convincing case. ‘I think they have nailed the locale of dog domestication to the Middle East,’ Dr. O’Brien said in an e-mail message from Siberia, where he is attending a tiger management workshop.”

In addition to Dr. Wayne and Ms. vonHoldt, there were many authors of the Nature article, including Dr. John Novembre of UCLA, Dr. Elaine Ostrander of the National Human Genome Research Institute, and Dr. Carlos Bustamante, formerly of Cornell University and now at the Stanford University School of Medicine. [Press release] [Nature abstract]