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It might sometimes feel hard to believe when you're looking at a Chihuahua in a cushy dog bed or a golden retriever in a yellow raincoat and boots, but domestic dogs - yes, all domestic dogs - are the descendants of wolves. Now, scientists have long wondered when this switch happened. When did wolves become dogs? As NPR's Nate Rott reports, a pair of new studies gives us the clearest answer yet.
NATE ROTT, BYLINE: If you don't have a time machine, there are a couple of ways to look into the past - using ancient DNA and bones. For more than a decade, an international team of scientists have been using both to try to better understand the origin of dogs. Carly Ameen, a bioarchaeologist at the University of Exeter, focused on bones, specifically the shape of skulls. And she says, in part because of humanity's unique relationship with dogs, there were many skulls to look at.
CARLY AMEEN: Usually, the animal bone from archaeological sites is very fragmented. It's broken because it's the refuse and the waste or the trash.
ROTT: Like the discarded remains of a chicken wing.
AMEEN: But dogs, when they die, for whatever reason, they're often deposited in very different ways than you would just throw away your food trash. And that means that their bones preserve a bit better because they're often intentionally buried.
ROTT: That allowed Ameen and her fellow scientists to make detailed 3D models of more than 600 skulls, dating as far back as 50,000 years ago, that they could then search for subtle changes. And one of the biggest surprises they found was that dogs showed a wide range of physical diversity a very long time ago.
AMEEN: By about 10,000 years ago, half of the amount of diversity present in modern dogs is already present in the Neolithic. So very early on in our relationship with dogs, we not only change them from wolves, but they begin to change amongst themselves and generate a lot of diversity.
ROTT: Not the most extreme changes we see today. Looking at you, French bulldogs. Those were the results of selective breeding within the last few hundred years. But even the oldest sample of a known dog, from about 11,000 years ago, didn't look much like a wolf. Meaning?
LAURENT FRANTZ: It's not a recent dog.
ROTT: Laurent Frantz is a professor of paleogenomics at the University of Munich, and he says the genetic analysis from that same skull shows that it was a hybrid of distinct Western and Eastern dog breeds.
FRANTZ: So that means that by 11,000 years, you already had dogs all the way in Siberia and in Europe for thousands of years, probably. And not only have you had them in these two separate parts of Eurasia for long enough for them to become different...
ROTT: But you also had time for them to be brought back together, probably by humans so they could breed.
FRANTZ: So we're looking at a time where everybody had dogs already.
ROTT: Meaning the wolf-to-dog domestication had to have happened sometime earlier. Both studies published in the journal Science narrow the window, Ameen and Frantz say, to understanding when this shift happened. And if you're wondering why any of this matters - like, why we should care when a wolf became a dog - Ameen says, consider how important humanity's ability to domesticate wild animals is and has been to our existence. Take cows, sheep, goats, all sorts of plants.
AMEEN: Without them, we have no food. Without them, we have no plants to eat. We have no cereal. Like, the domestication of plants and animals is an enormous impact on human history. It's possibly one of the most important things that humans have ever done. And the dog is the first species we make this relationship with.
ROTT: So the next time your dog is barking at the delivery person or begging for food, take a breath and appreciate the fact that both you and your furry companion are part of a long, storied tradition. Nate Rott, NPR News.
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