From National Geographic:
Labradors may be the most popular breed of dog, but the most populous kind is no breed at all. That distinction goes to the humble village dog scratching out a semiwild living in and around human settlements.
While a postdoc at Cornell University a few years ago, Adam Boyko became curious about the little-studied village vagrants. Though dogs were first domesticated 20,000 to 15,000 years ago, most breeds go back only a few hundred years. Perhaps village dog DNA might shed light on the long, early history of domestication, when canines were hanging around humans yet not under our domain. But how to get samples?
As it happened, around the same time Boyko’s brother Ryan had married, and he and wife Corin were looking for a cheap honeymoon off the beaten track. The three Boykos decided to merge their two quests. Adam—now at Cornell’s College of Veterinary Medicine—obtained a grant, then enlisted Ryan and Corin to spend their honeymoon traveling around Egypt, Uganda, and Namibia, befriending villagers and local vets. They collected DNA from more than 300 village dogs.
When the samples were analyzed, most of the village dogs turned out to be as closely related to wolves as they were to fully domesticated dogs. Rather than being mixed-breed mutts that had gone feral in historical times, the village dogs had been eking out an existence on the human fringe for millennia. Their genomes thus reflected a state of early domestication, before artificial selection and inbreeding directed by humans had taken over. “When you are looking at village dogs,” Adam Boyko says, “you have something more akin to natural selection, albeit in an environment that’s managed by humans.”
Unexpectedly, the study also helped to challenge the reigning view on the place where dogs first appeared. Fossil evidence had already pinned the transition from wolf to dog somewhere in Europe or Asia, and a 2002 study had shown that East Asian village dogs were more genetically diverse—an indication that wolves had first been domesticated in East Asia. But the Boykos’ 2009 work found that the African village dogs were just as diverse as the East Asian ones. Some also carried a genetic signature shared with Middle Eastern gray wolves, supporting research by Robert Wayne and Bridgett vonHoldt of UCLA that points to the Middle East as the likely cradle of dogs.
The Boykos continue to expand their sample collection, with another expedition planned for Africa. And they’ve also begun using the same techniques to solve a related mystery: the strange disappearance of native dogs in South America. We know from the historical record that Native Americans had dogs. But previous population surveys in the Americas turned up only dogs with European heritage. “How do you ship so many dogs across the world that they completely replace the native dogs?” Boyko wonders, suspecting that in fact there may still be village dogs with native DNA in the remotest areas of the continent. So in August the three Boykos packed their bags and headed into the jungles of Peru, searching for the lost American dog.
I have written about the discovery that African village dogs were just as genetically diverse as East Asian dogs– which in part falsifies the hypothesis that dogs originated in East Asia. People like that hypothesis for some odd reason.
I did not know that the Boykos had discovered that some these African village dogs showed an affinity with Middle Eastern wolves, which I think is very supportive of the hypothesis that Middle Eastern wolves– or very close relatives of the– are the most important population that contributed to the domestic dog.
Now, it doesn’t mean that phenotypically distinct domestic dogs first appeared in the Middle East. It just means that this population contributed to the majority of dogs we have today. The small dog gene that is found in purebred dogs is also found in some Middle Eastern wolves–likely coming from Canis lupus arabs. The smallest members of that subspecies weigh only 25 pounds.
I’m very excited that the Boykos are now looking at Latin American dogs to see if any possess indigenous ancestry. We know that virtually all Native American dogs in the US and Canada have largely been swamped with Western dog blood. Testing village dogs in remote areas of Peru might yield some interesting results, but keep in mind that “double-nosed” village dogs were found in Bolivia a few years ago. They likely derive “double-nosed” pointers that the Spanish brought over. Native peoples liked to use European dogs for the hunt, and in the colonies that later became the United States, laws were passed to prevent European colonists from selling their dogs to the Indians.
Native Americans’ preference for Western dogs would have been an important factor in the extinction of Native American dog strains.
Another important factor is that these dogs may not have had much resistance to European dog diseases. Just as their human owners were no match for small pox, it is possible that common diseases in European dogs were quite devastating to Native dog populations.
And then there is also the simple fact that Native peoples were conquered– and in some cases, exterminated. Massive social disruption leads to people not being able to care for their dogs– much less selectively breeding them. These dogs wound up wandering the countryside, where they either melded into the wolf or coyote population in North America or were shot on sight.
Any dogs that proved useful to the new order in the Americas were quickly absorbed into the growing Western-derived dog population.
To answer the Boykos’ question from an historical perspective, the Spanish were bringing over scores of dogs. Dogs were a major tool of conquest and colonization. The Navajo and Apache herders use their dogs as livestock guardians– a technique they got from the Spanish. The sheep they keep are derived from an old Spanish strain, and it is possible that their dogs trace to Spanish and maybe some remnant Native American dogs.
It will be interesting to see if the Boykos’ work reveals any clues to the extinction of Native American dog strains in South America. It will also be interesting to see if they find any dogs with clear indigenous ancestry. As far as I know, only the dominant hairless mutation that is found in xoloitzcuintli, Peruvian Inca orchids, and “Chinese crested dogs” has been traced to the Americas before the arrival of Columbus.
It will also be interesting to see if any of these dogs, if they prove to have ancestry from indigenous dogs, share signatures with North America wolves or coyotes or with wolves from East Asia. The VonHolt and Wayne study mentioned in this article found that certain East Asian breeds have an affinity with Chinese wolves. Because Native Americans came to the New World via Asia, it would make sense that some of these dogs would show some affinity with Chinese wolves– just as these East Asian breeds do.
I don’t know if they can be answered!
See related post:
- Twigs versus logs and the origin of the origin of the domestic dog (Critiques the supposed proof from y chromosome and mtDNA analysis that claims dogs have an East Asian origin. The bulk of the evidence points to the Middle East as the main source for domestic dog genetic diversity.)