Dogs evolved from wolves 40,000 years ago, according to new research of genetic material. This is several thousand years before the split was believed to have taken place, and could push back the accepted time when humans first became companions to canines.

The DNA from a Siberian wolf who lived 35,000 years ago was examined by researchers studying the branch of the family tree that includes both dogs and wolves. This genetic material suggests that humans may have started domesticating dogs between 27,000 and 40,000 years before our own time. Investigators theorize that the first domesticated dogs may have been companions to human hunters during the last major ice age.  

Previous genetic analysis had placed the separation of dogs and wolves at between 10,000 and 30,000 years ago. However, fossils of doglike animals have been found from before that time.

The rib bone from which the DNA was extracted was found on an expedition to the Taymyr Peninsula in Russia during 2010. When the bone was first found, researchers believed it may have come from a long-dead reindeer. Initial analysis showed the artifact was the remains of a wolf, and radiocarbon dating placed its age around 35,000 years old. This was thought to be well before the domestication of dogs, but the genetic code showed a nearly equal representation of DNA from wolves and modern canines.

Ancient humans may have kept wolves in captivity before they were fully domesticated, although the creatures likely retained the body features of wolves over thousands of years, researchers stated. Canines may have first been domesticated by early humans settling the continents of Asia and Europe.

Even after dogs split off the genetic tree containing wolves, the two types of animals likely interbred for a period of time. Dogs from Greenland and Siberian huskies have each been shown to possess more genetic material from wolves than other canines around the world.

"As for the genetic link between the 35,000-year-old wolf and Husky-type dogs, the most natural explanation is that these dog breeds absorbed local wolf ancestry that still lived on in Siberia when they followed early human groups to this region. This is the first direct evidence we have that the diversity in common dog breeds today has such deep roots," Pontus Skoglund, a geneticist from Harvard University, said.

If this analysis is correct, then dogs were domesticated well before other species, such as chickens, pigs, and cattle. Some researchers believe domesticated dogs may have helped ancient humans out-hunt Neanderthals, leading to our modern-day species.

"There's something there we don't quite understand yet. Dogs were fundamentally important to humans in a way that other animals weren't," Robert Wayne of the University of California, Los Angeles said.

Analysis of the genomes of dogs and wolves, and what it can tell us about the domestication of canines, was detailed in the journal Current Biology.

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