Humans have been hanging out with dogs for even longer than we thought
Two new papers have shown that dogs were fully distinct from wolves—and companions with people—more than 14,000 years ago.
While scientists have known that dogs were our first domestication relationship, before even agriculture took root, exactly how far back our best friendship goes just got pushed back another few thousand years.
Two new papers, published March 25 in the journal Nature, have compared genetics from canines found in ancient human sites across Europe, and shown that dogs were genetically distinct from wolves—and buddy-buddy with people—more than 14,000 years ago. Even before farming, dogs were a common part of life across many ancient cultures, potentially aiding in guard duty, hunting and as a part of rituals.
“Once you have dogs, these dogs are attached to human populations through time,” says Lachie Scarsbrook, a paleogeneticist at the Ludwig Maximilian University of Munich in Germany. “We call it the Swiss Army Dog. They can adapt to all these cultural roles we associate with dogs today.”
Old bones, new tricks
Archaeologists have uncovered canines buried alongside humans dated to 34,000 years ago. But simply something dog-like buried next to a human does not a dog make, Scarsbrook explains. “The burying of an animal alongside humans is a risky strategy to use to identify something as domestic. We know people for millennia have been burying wild animals alongside people,” he says.
Dog and wolf skeletons also can look extraordinarily alike—especially when there’s only a part of a skull or a single tooth to go on. “A lot of very, very early putative dogs, when you run the DNA on them, they actually come out as wolves,” says William Marsh, a paleogeneticist at the Natural History Museum of London. Previous studies have dated the oldest definitely-dog to around 10,900 years ago. By then, Marsh says, the “dogs are genetically very, very distinct from a wolves.” That means dogs must have been around, becoming more doggish, thousands of years earlier to the Upper Paleolithic period between 12,000 and 50,000 years ago.
“We would kind of imagine that if dogs were in Europe this early, then there will be more of them,” says Anders Bergström, an evolutionary geneticist at the University of East Anglia in England. “So we kind of embarked on this large search for early dogs in Europe, and we basically tried to kind of sample as widely as we could.”
Proof of pooch
Bergström and his colleagues took samples from the remains of 216 canines buried near humans across thousands of years, from a 46,000-year-old site called Goyet in Belgium to 5,000-year-old skeletons from Scotland. They compared what they could reconstruct of their DNA, working to distinguish dog from wolf. The oldest sample that came up as a dog was 14,200 years old, from a site in Switzerland.
Meanwhile Scarsbrook, Marsh and their colleagues took samples from eight canid remains spread from Turkey, Iran, Serbia, and England. These bones dates from between 15,800 to 8,900 years old. They examined the remains of the DNA in the cell nucleus, as well as the DNA in their mitochondria, passed down only from the mother.
Scarsbrook and Marsh showed that six of their samples were dogs, all of which were fairly similar to each other—indicating that Europe had a consistent lineage of dogs across the continent by 14,300 years ago.
While the studies can’t offer ideas about what these early pups looked like, the animals in these studies were probably not Pomeranians in cute outfits. “We’re suspecting they would have kind of resembled smaller wolves,” Scarsbrook says. But the genes of these dogs have persisted, he says, “and ended up in many of the modern dogs breeds we know and love today, like the German Shepherd and St. Bernard.”
(Are foxes becoming domestic?)
Different peoples, same dogs
While the groups found similar timelines, they chased down slightly different details. With their large genetic dataset, Bergström’s group was able to examine how dog DNA changed after the rise of farming. Agriculture arose in the Fertile Crescent in the Middle East around 12,000 years ago. But then “people migrated into Europe at large scale, brought with them domesticated animals and crops and so on,” Bergström explains. This was not a peaceful influx. “They replaced something like 80 to 90 percent of the genetic ancestry of humans in Europe,” he says. This “replacement” of people was dramatic—and possibly violent.
But with their DNA analysis, Bergström and his colleagues showed farmers didn’t fully replace the old dogs. “They actually incorporated them into their own dog populations,” Bergström says.
Instead of looking at genetic changes across time, Marsh, Scarsbrook and their colleagues examined genetics across space and three different cultures. The Magdalenian culture occupied western Europe in France and Spain up to the United Kingdom around 14,000 years ago, while the Epigravettian was centered further east toward Germany and Italy. The Anatolian hunter-gatherers were based in what is now Turkey.
All these cultures had similar dogs. Dogs they cared for. Like many modern cultures, the Anatolian people buried their dead—and alongside them, they also buried their puppies, “suggesting that they kind of had that same personhood,” Scarsbrook says.
The Magdalenian culture, on the other hand, respected their dead with funerary cannibalism. Human remains from the period shaped skulls into cups, butchered, and left bone engravings. Similarly, their dog skulls showed holes and other modifications to indicate butchering after death. “They all seem to treat these dogs in a very, very symbolic manner, similar to how we treat our dogs,” Marsh says.
Our puppies, ourselves
The papers are “incredible works of phylogeography and population genomics,” says Emily Puckett, a phylogeographer at the University of Memphis in Tennessee. But they also “clearly tell us something about humans with this layered approach.”
While the results show domestic dogs were all over Europe 14,000 years ago, that does not mean that’s when they were domesticated, which likely happened much earlier outside of Europe, says Krishna Veeramah, a population geneticist at Stony Brook University in New York. After all, the dogs in these studies could be distinguished from wolves. The first very good boys (and girls) would be much closer to their wolf ancestors. Domestication is “a long process,” he says. “It's a multi-generational thing. It can’t happen all of a sudden.”
(Maybe dogs didn't need us at all to domesticate themselves.)
Until scientists uncover even older bones, to trace back when dogs and wolves diverged, exactly when domestication took place will remain a mystery, one that leaves many questions about the birth of the first Fido. “You can imagine it just opening up a new part of our brain,” Scarsbrook says. “We have these dogs who we're previously in conflict with. We now have this species…who now sort of is in cahoots with us to some degree, and that's fascinating.”
