Three Dog Eves: Canine diaspora from East Asia to Americas
Two genetic studies have just rewritten the history of humanity's best friend. The new version has moved the origins of the domestic dog from the Middle East to East Asia and argues that the first people to venture into the Americas brought their dogs with them.
OUT OF ASIA. Even an all-American pal has a pedigree stretching back to the Old World.
Analysis of 654 dogs from around the world suggests that their earliest female ancestors originated from several lineages of wolves primarily in one region, says Peter Savolainen of the Royal Institute of Technology in Stockholm. The patterns of genetic diversity point to East Asia as the likeliest place for the canine Eden, Savolainen and his colleagues argue in the Nov. 22 Science.
"This has been the search for the dog Eve," says Savolainen.
The same issue of Science also reports on extraction of bits of DNA from New World-dog remains predating European influence. This DNA shows that early New Worlders did not domesticate dogs anew, say Jennifer Leonard of the Smithsonian Institution in Washington, D.C., and her colleagues.
"The first Americans came across the Bering land bridge with their dogs, and this was something we couldn't prove before," says coauthor Robert K. Wayne of the University of California, Los Angeles.
Dogs were probably the first domesticated animals (SN: 6/28/97, p. 400: and have unusual sensitivity to signals from people (see Dog Sense, in this week's issue: ).
Savolainen started studying dog genetics to help crime-scene investigators analyze hairs. "I've been to a lot of dog shows here, snatching hairs from the dogs," he says.
As he assembled a large collection of dog hairs and attached cells, he began to wonder whether he could expand it and find the cradle of the domestic dog.
He and his international partners focused on stretches of DNA from the cells' mitochondria, or powerhouses, which pass from mother to pup. Based on similarities in that genetic material, 95 percent of the dogs that the researchers had sampled come from just three lineages that seem to have arisen in East Asia, Savolainen and his colleagues say.
To study New World dogs, Leonard and her colleagues worked with DNA from remains up to 1,400 years old. Thirty-seven came from archaeological sites in Peru, Bolivia, and Mexico, and 11, from modern gold mines in the Alaskan permafrost.
When the researchers constructed a family tree that includes modern dogs and wolves, they found that the ancient New World dogs were much closer to Old World dogs than to New World wolves. Also, the ancient New World lineages seem to have disappeared from modern breeds.
The two new studies agree with suggestions from older work: Dogs were domesticated in the Old World, and the earliest migrants brought them to the New World, comments geneticist David Hillis of the University of Texas at Austin. He is convinced by the new data that the major lineages of dogs originated in East Asia, but he sees evidence in the Savolainen study that some rarer lineages evolved elsewhere.