The first dogs of America have lived with people for thousands of years. Then they disappeared | Science

By David Grimm Jul. 5, 2018, 2:00 PM

When 19th century naturalists and explorers first encountered Native American dogs, they were shocked by the fact that they had been killed. werewolf appearance of the canines. The animals were tall and strong, and they did not bark, they screamed. "If I had to meet one of them in the woods," noted John James Audubon, "I should definitely kill him."

But today, these dogs and their parents can not be found, their genetic inheritance is erased from the genomes of all living canines. Now, the DNA recovered from many of these ancient animals has revealed where the first American dogs came from – and how they could have disappeared.

"It's really a good research," says Jennifer Raff, an anthropologist geneticist at the University of Kansas at Lawrence. and an expert on the settlement of North America. The work supports the emerging evidence that early Americans did not bring dogs with them. In the 1960s and 1970s, archaeologists searched two sites in western Illinois, where former hunter-gatherers were collecting shells in a nearby river and stalking in the surrounding forests. These people also seem to have buried their dogs: one was found on a site known as Stilwell II, and four on a site called Koster, curled up in individual gravelike pits.

The radiocarbon bone badysis reveals that they are around 10,000 years old, making these dogs the oldest known dogs in the Americas, the researchers report in an article published on the bioRxiv server that will be published shortly in Archeology. He also makes it the oldest dog burials in the world

The Stilwell II dog was the size of an English setter, while the Koster dogs were smaller and thinner, says lead author of the study, Angela Perri, zooarchaeologist at the Max Planck Institute of Evolutionary Anthropology in Leipzig, Germany. "It would not be surprising that they are all used as hunting dogs." But where did they come from in the first place?

A second study, published today in Science could have the answer. A large international team of researchers sequenced DNA mitochondria, or cellular power plants, from 71 bone dogs of North America and Siberia, including those from one of the Koster dogs, dating to from about 10,000 to 1,000 years old. When they compared this matter, which is pbaded on only by the mother, to that of 145 modern and ancient dogs, they discovered that the old American dogs have a genetic signature that is not found in any other dog.

group that has its own story, "says Perri, also a senior author on the article Science .This means that the wolf-like dogs that Audubon encountered were in genetically distinct effect of European dogs.

These "pre-contact" dogs, as the team calls it, are very close to the 9000-year-old dogs of Zhokhov Island, hundreds of kilometers away North of the Siberian mainland.If baduming a relatively constant mutation rate of DNA and using it as a "molecular clock", the team concludes that both groups of dogs can having shared an ancestor almost 16,000 years ago, we still do not know exactly where and when the dogs appeared, but that could have been at that time.

Taken together with the archaeological finds, the data suggest that the first dogs may have come to Siberian Americas thousands of years after the first people. , says team leader Laurent Frantz, an evolutionary geneticist at the University of Oxford in the UK. Humans probably came to America about 16,000 years ago by the Bering Land Bridge, which connected Siberia to Alaska. The bridge disappeared about 11,000 years ago – at that time, the dogs must already be handed over, says Frantz.

Dogs may have been hanging out with people in Alaska for a while. North America, where they ended up in sites like Koster and Sitwell II. "People were moving a lot," says Raff. Once they saw how useful the dogs were – to hunt deer, haul supplies, and keep the camps – humans might have started to bring others for the trip.

"It's a tidy story. Says Melinda Zeder, an archaeozoologist at the National Museum of Natural History at the Smithsonian Institution in Washington, DC. But she notices that molecular clocks are only an approximation and that other mysterious bones found in Siberia and the Yukon may belong to dogs. in the Americas earlier by thousands of years. "It's hard to draw a firm conclusion."

An additional badysis of the nuclear genome – inherited from two parents – of seven pre-contact dogs supports the idea that they are genetically distinct. Their closest living relatives are the Arctic breeds such as the Alaskan Malamutes and the Siberian Huskies. These modern dogs can come from the same Siberian source population as precontact dogs, but thousands of years later. "If you have an Arctic dog, you probably have an old dog," says Perri. "If you have another dog, it has probably come from Europe or Asia much more recently."

This is even true for supposedly ancient dogs like the South American Xoloitzcuintli, which seems to have existed for thousands of years. "Dogs of today can look like these dogs," Frantz says. But according to the samples taken so far, "their genetics is totally different."

Indeed, the team found virtually no genetic trace of precontact dogs in any modern dog. "Overall, their genetic signature has disappeared," says Perri. She and Frantz speculate that just as European settlers have eliminated a large number of Native Americans with their diseases, European dogs may have even more devastated American dogs. The Europeans may have also feared these wild dogs, like Audubon, and tried to eliminate them, Perri said.

The only trace of these first dogs can survive in a badually transmitted canine cancer, which has retained the genetic signature. the first dog in prey. When the team compared the genomes of two of these tumors to modern and ancient dog genomes, the DNA was most similar to that of precontact dogs, perhaps the one that lived about 8000 years ago . "It's fascinating," says Frantz, "but for the moment that does not tell us much about the history of the first American dogs."

If people did not bring dogs with them right away, it may be because they did not know how useful they would be. Or it could just be that the dogs did not exist yet. When this alliance was formed in the Americas, it probably mirrored that which takes place all over the world, where dogs were used for hunting, keeping or simple company. "It's crazy that we would have started a relationship with an animal that could hurt us and compete with us," says Perri. "There must have been a good reason."