Double-dog domestication: How many times did dogs become man’s best friend?

Some 14,700 years ago, a loyal dog was buried alongside its human companions near what is today Bonn, Germany. That dog is the oldest undisputed domesticated dog on record, though many scientists purport that dogs were first domesticated far earlier, between 20,000 and 40,000 years ago.

It’s actually hard to say for sure where and when dogs were first domesticated. Scientists are unsure if it even happened all at once — in 2016, researchers looking at the DNA of modern and ancient dog species found that dogs were descended from two geographically distant wolf populations: one in Europe and one from Asia.

This led many to believe that dogs were domesticated in two different places, and that eventually their lineages came together. However, a recent study presented evidence suggesting that the Asian and European split could have instead occurred after domestication.

The team looked at the rate of mutations over time in the genomes of two ancient dog remains. Both dogs were found in Germany. One was around 7,000 years old, the other 4,700. The team compared its data to complete genomes and DNA snippets from 5,700 modern wolves and dogs.

The findings suggest that dogs split from wolves in a single domestication event between 36,900 and 41,500 years ago. This doesn’t completely rule out the double-domestication theory, rather it presents the single event taking place in Asia as a simpler explanation, according to scientists involved. Other scientists believe a single domestication event took place in Europe, based on other studies.

Not all are convinced either way, but the recent study presents more evidence to fuel the debate.

What we do know

Regardless of how they became domesticated, there’s one thing we do know about dogs: They are incredibly friendly to people. There may be a genetic basis for that.

Wolves usually aren’t as good at paying attention to humans and responding to commands as dogs are. This may be because hyper-social dogs carry variants of two genes called GTF2I and GTF2IRD1. When humans lack these genes, it causes Williams syndrome, which is characterized by distinct facial features, cognitive difficulties and a sociable, loving personality.

“We may have bred a behavioral syndrome into a companion animal,” evolutionary biologist Bridgett von Holdt told National Geographic.

Many dogs are, by nature, captivated by people. In an experiment with non-wild wolves and multiple dog breeds, the canines were instructed to open a box containing sausage in three scenarios: with a familiar human, with a stranger, and totally alone.

Who performed better? Wolves, by a large margin, especially when in the presence of humans.

“It’s not that they couldn’t solve the puzzle,” said von Holdt of the participating dogs. “They were just too busy looking at the human to do it.”

Neogen’s GeneSeek laboratory is a leader in companion animal genomic testing. For more information, click here.

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