Cute puppies (Photo : Reuters)
Man's best friend has been man's best friend a lot longer than we thought, says a new study that showed the close relationship between dogs and man might have begun 40,000 years ago.
Previous theories suggest dogs diverged from wolves 11,000 to 16,000 years ago but this new study by Swedish researchers said this event took place 27,000 to 40,000 years ago.
The origin of domestic dogs is poorly understood and this new finding seems to demonstrate the ancestry of present-day dogs is derived from multiple regional wolf populations.
In the study published in the journal Current Biology, researchers radiocarbon-dated a Taimyr wolf bone they found in Siberia and concluded it to be some 35,000 years old. They noted the Taimyr wolf is possibly the most recent common relative of modern wolves and dogs.
Researchers said this ancient Siberian wolf yielded a first draft genome sequence of a Pleistocene carnivore that allowed recalibration of the lupine or wolf mutation rate.
They found this individual belonged to a population that diverged from the common ancestor of present-day wolves and dogs very close in time to the appearance of the domestic dog lineage.
"We use the directly dated ancient wolf genome to recalibrate the molecular timescale of wolves and dogs and find that the mutation rate is substantially slower than assumed by most previous studies, suggesting that the ancestors of dogs were separated from present-day wolves before the Last Glacial Maximum", researchers wrote in their study.
They also found the Taimyr wolf contributed between 1.4 percent and 27.3 percent of their ancestry lineage into present-day dog breeds from northeast Siberia and Greenland.
"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," said study co-author Love Dalen of the Swedish Museum of Natural History.
Under that theory, the second wolf population would have gone extinct, however.
"It is (still) possible that a population of wolves remained relatively untamed but tracked human groups to a large degree, for a long time," said study co-author Pontus Skoglund of Harvard Medical School and the Broad Institute.
Previous research gave genetic mutation rates that were much faster than what these researchers found. But the mutation rate in the Taimyr wolf genome was just half of what had been thought, Dalen told Reuters
"The difference between the earlier genetic studies and ours is that we can calibrate the rate of evolutionary change in dog and wolf genomes directly, and we find that the first separation of dog ancestors must have been in the older range," said Skoglund.
