04 July 2016

RESEARCH - Dogs May Have Been Domesticated Twice

Scientists have theorized for years about when and where and how dogs were domesticated, without ever reaching a consensus.

Were they domesticated in East Eurasia and traveled west? In West Eurasia and traveled east? Where did they first become our companions, and how did our relationship with them develop?

These questions hold a lot of interest for scientists and for dog lovers, because our relationship with dogs is unique.

Not only are dogs an integral part of many people’s lives and critical in industries from farming to health care, they are also the only animal domesticated before the development of agriculture.

It’s possible that the reason scientists could never come to an agreement on the origin of domestic dogs is because they were each contributing a piece to a puzzle that is much bigger and covers much more geographical area than anyone anticipated.

Although domesticated animals are all around us – dogs, of course, but also horses, chickens, pigs, and others – the process of domestication is rare and complex. It doesn’t happen often, and no one understands exactly how it happens even though there are clues as to the when and where of it happening.

Now there is a better understanding of when and where it happened with dogs, and the answer isn’t East Eurasia or West Eurasia, the answer is both.

New research suggests that dogs were domesticated twice, at separate times and in separate locations, from two distinct wolf populations - once in Eastern Eurasia, and once in Western Eurasia.

The scientists combined ancient genetic material from 59 dog DNA fragments found across the European continent with 167 sequences of modern dog DNA.

They were able to sort these sequences, and determine that there was “clear turnover in the mitochondrial ancestry of European dogs,” meaning that at some point there was an introduction of new DNA in the European dog population. This new DNA came from East Asian dogs, dogs that had been domesticated from a separate wolf population.

In addition to the DNA evidence, the archaeological evidence also supports the idea of two distinct domestication events.

Dog remains have been found in Eastern Eurasian sites as old as 12,500 years, and in Western Eurasian sites as old as 15,000 years. But the oldest dog remains found in Central Eurasia are approximately 8000 years old.

This suggests that there was not a single cross-continental dog population, but rather two separate populations that eventually made their way into Central Eurasia.

The archaeological evidence has presented a challenge to the understanding of dog domestication for years, because although it had been theorized that dogs had been domesticated twice, there wasn’t supporting DNA evidence.

And, as Professor Greger Larson told Science Daily, “Animal domestication is a rare thing and a lot of evidence is required to overturn the assumption that it happened just once in any species.”

This finding provides the evidence to overturn that assumption, and offers insight into humans’ long relationship with dogs. 

By Tiffany Sostar
Tiffany is a writer, editor, academic, and animal lover who came late to her appreciation of pets. At 18, a rescue pup named Tasha saved her from a depression and she hasn't looked back. She has worked as the canine behaviour program coordinator for the Calgary Humane Society, and was a dog trainer specializing in working with fearful and reactive dogs for many years. She doesn't have any pets right now, but makes up for it by giving her petsitting clients (and any dogs she comes across on her frequent coffee shop adventures) extra snuggles.

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