Dogs became man’s best friends somewhere in central Asia close to Nepal and Mongolia, according to the largest genetic study yet. The work looked at DNA from thousands of living dogs to piece together their ancestry and geographical origins.

“This is the first global study of genomic patterns of dog diversity,” says Adam Boyko of Cornell University in Ithaca, New York, who led the team. “We find a clear pattern of genetic diversity focused on central Asia, suggesting the first domesticated dogs came from this region.”

That departs from earlier studies that pinpointed Europe as where dogs were domesticated, although more recent work puts the location in southern China, just 1000 kilometres from the area Boyko’s team proposes.


The team broke new ground by analysing DNA samples from so-called “village dogs”, which have lived alongside humans throughout the world since dogs first evolved from wolves and were domesticated around 15,000 years ago. “Although they associate with humans, village dogs are more or less expected to make it on their own,” says Boyko.

Authentic signature

“They are very different from pure-bred dogs genetically because they are free-breeding, so in a genetic sense, they are a natural population.” Village dogs therefore carry a more authentic genetic signature of original dog populations than the modern-day breeds created in the past 200 years, mainly in Europe.

Boyko’s team took DNA samples from 549 village dogs in 38 countries all over the globe. They also took samples from 4676 pure-bred “modern” dogs of 161 breeds, many of European origin.

To further improve the reliability of the analysis, the team broadened the amount of DNA examined to include chromosomes inherited from both parents. Previous studies had relied mainly on mitochondrial DNA transmitted through the female line, or DNA from male sex chromosomes.

By analysing 185,805 genetic markers, Boyko’s team traced how all the animals were related, and from that how they had spread around the world. This essentially gave them a trail back to “founder” dogs in Nepal and Mongolia.

The analysis also revealed that following domestication, village dogs rapidly fanned out to other areas of Asia, particularly India and south-west and east Asia.

Scavenging

Boyko’s team speculates that hunter-gatherers in central Asia domesticated dogs from grey wolves. A combination of increasing human population density, better hunting methods and climate change may have reduced the availability of prey and pushed some wolves towards scavenging, which favoured tameness and smaller size. This would in turn have reduced their hunting prowess further, setting them on the path to domestication.

Other researchers have welcomed the tracing of domestication to the neighbourhood of central Asia, although some dispute the precise site.

“They are actually putting the origin very close to where we put it, just 1000 kilometres away in parts of Asia south of the Yangtze river,” says Peter Savolainen of the Royal Institute of Technology in Solna, Sweden. “So I would say the consensus pointing to south and east rather than central Asia is quite clear.”

Savolainen compliments the thoroughness of the study, but says that what is lacking is DNA from southern China, where he thinks dogs originated. “Since they don’t have a single sample from south China, they haven’t falsified [my] theory,” he says.

Olaf Thalmann at Uppsala University in Sweden praises the scale of the study, and says its conclusion is reasonable. “We know that this region was pivotal for ancient trade, and it seems plausible that animals followed the trading routes and thus increased the local diversity,” he says.

But Thalmann doubts that the study is the final word on where dogs were tamed, because the DNA comes only from animals living today. “I’m convinced the only way to shed further light on the topic is by analysing ancient remains,” he says. A consortium led by Greger Larson of the University of Oxford is now looking to doing just that.

Larson says Boyko’s result is important because it reaches a clear conclusion that can be tested further. “We are excited to be working with Boyko’s group and others,” he says.

“Having collected more than 1500 ancient dogs and wolves over the past few years, our lab has begun our next-generation sequencing effort.” The genetic data will then be compared with morphological data from more than 4000 specimens going right back into the late Pleistocene, he says.

Journal reference: PNAS, DOI: 10.1073/pnas.1516215112

(Image credit: FLPA/REX Shutterstock)

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