The remains of the oldest American dog support idea that the first humans arrived along the coast | Science

By Andrew CurryFeb. 23, 2021 at 7:01 p.m.

When researchers began to excavate a tunnel-shaped cave on the west coast of Alaska in 1998, they hoped to find the remains of ancient bears. Instead, they unearthed something even more intriguing: a tiny bone chip belonging to the first known dog of the Americas. The discovery supports the idea that dogs accompanied the first humans to set foot on these continents – and that both traveled there along the Pacific coast.

“It’s a fantastic study,” says archaeologist Loren Davis of Oregon State University Corvallis, who was not involved in the research. “If the theory of coastal migration is correct, we should expect to see exactly the type of evidence reported in this study.”

Researchers once believed that humans entered the Americas around 12,000 years ago. It was at this point that thick glaciers that covered much of North America began to melt. This opened up a corridor, which allowed people to walk from Siberia through lands now submerged in the Bering Sea, and then across North America in search of mammoths and other big game.

But over the past decade, archaeologists have shown that people may have started settling in North America much earlier. To get around the glaciers, they would have jumped onto the island by boat and walked along shores exposed by low sea level. They traveled from Siberia to the Alaskan archipelago about 16,000 years ago. , to finally descend the Pacific coast.

Dog bone ribbon supports this hypothesis. Recovered from more than 50,000 prehistoric animal and human remains found near Wrangel Island, researchers did not realize it was from a dog until they analyzed its DNA. “We started to think it was just another bear bone,” says team leader Charlotte Lindqvist, a biologist at the University of Buffalo (UB). “When we went further, we found out it was a dog.”

The bone is around 10,200 years old, making its owner the oldest known dog in the Americas, scientists in the Proceedings of the Royal Society B: Biological Sciences. (The previous record holders were two 10,000-year-old dogs discovered in the American Midwest.) And the dog’s DNA contains clues to an even older era.

The puppy’s genome has revealed that it is closely related to the first known dogs, which researchers believe were domesticated in Siberia around 23,000 years ago. Based on the number of genetic differences between the Alaskan dog and its Siberian ancestors, the team estimates that the two populations split 16,700 years ago, roughly a few thousand years ago.

It’s a clue that dogs – and their humans – left Siberia and entered the Americas thousands of years before North American glaciers melted. “Here we have the genetic evidence, if not the physical evidence, [showing] dogs were already in the Americas with humans 16,000 years ago, ”said Durham University archaeologist Angela Perri, who was not part of the team.

The dates also match DNA-based estimates of when modern Native Americans separated from their ancestors in Siberia, which provides another line of evidence to determine when the first migrations took place. “Understanding how dogs moved also shows you how humans move,” says Flavio Augusto da Silva Coelho, a UB graduate student who performed DNA and other analyzes.

Perri agrees. The study shows that dogs are a useful way to track ancient human migrations, especially when human remains are missing or cannot be sampled due to concerns from the descendant community, she says. Even without human samples, “dogs can tell us some really interesting things” about our history, she says.

For example, the chemical isotopes in the dog’s bone suggest that the dog has eaten marine animals. Because dogs are not very good at fishing, their owners likely gave them leftover fish, seals, or whales that they hunted themselves. “It’s a strong indication that people are feeding their dogs,” Perri says. “Everything in this study indicates that people adapted to the ribs and their dogs are moving to the Americas.”