August 4, 2009
Researchers Challenge The Origins Of Domestic Dogs
Researchers are now questioning the idea that the domestic dog originated in East Asia.
Scientists have long concluded that domestication of canines began in East Asia, due to the huge genetic diversity of dogs found there. But new research published in the journal PNAS shows the DNA of dogs in African villages is just as varied.Blood samples from dogs in Egypt, Uganda and Namibia were analyzed by an international group of researchers who found that today's dogs are descended from Eurasian grey wolves, domesticated between 15,000 and 40,000 years ago.
The process by which humans domesticated the dog is still poorly understood, according to the authors.
The team, lead by Dr. Adam Boyko of the Department of Biological Statistics and Computational Biology at Cornell University, decided to look at village dogs - considered more genetically diverse than bred dogs - to see if they may hold the key to the origins of dog domestication.
The genetic diversity of 318 dogs from villages in Egypt, Uganda and Namibia were analyzed for the study.
The team also carefully looked at the genetic make up of dog breeds thought to be of African origin, like the Saluki, the Rhodesian Ridgeback, and the Pharaoh Hound, and compared all the resulting data with results for non African dogs such as Puerto Rican street dogs and non-pedigree dogs in the United States.
However, genetic diversity among African village dogs is just as diverse as that of East Asian dogs, which lead the researchers to question the hypothesis of an East Asian origin for dog domestication.
"The conclusion that was drawn before might have been premature. It's a consequence of having a lot of street dogs from East Asia that were sampled, compared to elsewhere," said Boyko.
He said the reason that East Asia looked more diverse than elsewhere was not because East Asia as a continent had more diverse dogs than elsewhere but because non-breed street and village dogs are more diverse than breed dogs.
However, the team is not ruling out East Asia as a possible location for the origin of the domestic dog - but it could equally have been anywhere else on the Eurasian landmass where there were both grey wolves and humans.
"It's interesting to know the answer to the question of where dogs were first domesticated and this paper goes some way to giving us an answer," said co-author Paul Jones of The Waltham Center for Pet Nutrition.
The research team is now sampling street and village dogs across Europe and Asia from Portugal to Papua New Guinea to pinpoint the areas of greatest genetic diversity.
All the dogs sampled in the study have grey wolf DNA, so they're not questioning the hypothesis that dogs descended from Eurasian wolves, Boyko said.
The study led them to the conclusion that African village dogs are a mosaic of indigenous dogs descended from early migrants to Africa.
Image Courtesy Lisa Raffensperger, National Science Foundation
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