Search into the genetic origins of dogs hits some obstacles

The scientific consensus is that dogs came from wolves. Beyond that, there are varying claims. It seems dogs appeared sometime between 15,000 and 100,000 years ago, in Asia or Africa or multiple times in multiple places.

There is a reason for this confusion, according to Greger Larson at the University of Durham in England. In a new research paper, he argues that the DNA of modern dogs is so mixed up that it is useless in figuring out when and where dogs originated.

The DNA of dogs is so mixed up that it is of little help to researchers who are tracing their origins.  [Photo/Agencies]

"With the amount of DNA we've sequenced so far," Dr. Larson said, "we're lucky to get back a hundred years, max." He says that only with the analysis of DNA from fossil dogs, now being done, will answers along this line emerge.

Dr. Larson, the first of 20 authors on a paper about the origin of dogs published May 21 in The Proceedings of the National Academy of Sciences, argues that genetic study of modern breeds does not "get us any closer to understanding where and when and how dogs were domesticated."

Dr. Larson and his colleagues analyzed 49,024 locations on dog DNA where the genetic code varies, so called SNPs (pronounced snips, for single nucleotide polymorphisms). They took the DNA from 1,375 dogs of 121 breeds, and 19 wolves.

What they found was that all the so-called modern breeds had been so mixed that their deep genetic history was obscured.

They also found six breeds that they called basal, meaning that their DNA was less mixed - the basenji, shar-pei, Saluki, Akita, Finnish spitz and Eurasier.

When they added these to eight breeds deemed ancient (older than 500 years) in other studies, what they found was that the dogs that were most genetically distinct were not from the places where the oldest archaeological and fossil evidence had been found. Dr. Larson said that the expectation was that if these breeds were closer genetically to the first domesticated dogs, they would be geographically closer as well.

Instead, the more genetically distinct dogs had been geographically isolated relatively recently. Dingoes, basenjis and New Guinea singing dogs came from Southeast Asia and southern Africa, where dogs did not arrive until 3,500 and 1,400 years ago, respectively. Their distinctive genes were indications of relatively recent isolation.

But, Dr. Larson said, humans have buried their dogs for a long time, and as a result there are fossils of truly ancient dogs, in the neighborhood of 15,000 years old, from which DNA can be extracted. Just as DNA from Neanderthals has helped illuminate the origins of modern humans, DNA from ancient dog fossils should help illuminate the story of early dog domestication in the next few years.

"Let's step back," he said. "Let's take a breath. We're not a million miles away" from figuring out when and where dogs appeared. "We're close."