Researchers analyzing DNA isolated from an ancient Siberian wolf bone have discovered that dogs originated at least 27,000 years ago, and maybe even as far back as 40,000 years ago. The findings, published in Current Biology this week, suggest that dogs became domesticated thousands of years earlier than we thought.

Researchers can’t seem to agree on when dogs became domesticated from their wolf ancestors. According to some genome-based estimates, ancestors of today's canine companions diverged from the ancestors of modern-day wolves (Canis lupus) between 11,000 and 16,000 years ago, after the last Ice Age. But dog-like fossils started showing up in the archaeological record around 36,000 years ago.

For another look at the origin of domestic dogs, a team led by Harvard’s Pontus Skoglund and the Swedish Museum of Natural History's Love Dalén analyzed a wolf rib bone (pictured below) collected in 2010 during an expedition to the Taymyr Peninsula of northern Siberia. Based on radiocarbon dating, the bone is 35,000 years old.

The team then drafted the genome sequence of the Taymyr wolf and their findings suggest that the split between the ancestors of dogs and those of wolves occurred between 27,000 and 40,000 years ago. When they compared this genetic material to DNA from dogs and wolves (both modern and ancient), they discovered that this individual wolf belonged to a population that diverged from the most recent dog-wolf common ancestor right around the time the domestic dog lineage first appeared.

"Dogs may have been domesticated much earlier than is generally believed," Dalén says in a news release. "The only other explanation is that there was a major divergence between two wolf populations at that time, and one of these populations subsequently gave rise to all modern wolves." However, this latter explanation implies that there was a second population of wolves that became extinct.

What’s also interesting is that the split could have occurred with or without domestication, New Scientist reports. It’s possible that some wolves stayed untamed but tracked humans around for a long time afterwards. Or, “it’s quite possible that wolves were held captive, then they were domesticated – but kept looking like wolves for many, many thousands of years,” Dalén tells Nature.

According to the draft genome sequence, modern-day, high-altitude breeds – such as Siberian Huskies and Greenland sled dogs – share an unusually large number of genes with the Taymyr wolf. "The power of DNA can provide direct evidence that a Siberian Husky you see walking down the street shares ancestry with a wolf that roamed Northern Siberia 35,000 years ago," Skoglund adds. For some perspective, “this wolf lived just a few thousand years after Neanderthals disappeared from Europe and modern humans started populating Europe and Asia."

Images: Love Dalén