7,400 years ago, Siberian dogs were much smaller than wolves, which made them more dependent on humans for food, including marine species, according to research released this Friday (22).
Robert Losey, a professor at the University of Alberta and director of the study published in Science Advances, said the findings helped explain the early growth of the canine population, which humans turned to for housework, herding and sled transport.
Previous research had focused on just two main ideas to explain how dogs changed from being wolves, a process that began about 40,000 years ago.
The first of these assumptions is that the friendliest wolves approached human camps during the Ice Age to forage for meat, isolated themselves from their wild counterparts, and then were intentionally bred as dogs.
The second is that some dogs developed a better ability to digest starch after the agricultural revolution, which is why some modern breeds have more copies of the gene AMY2B, which creates pancreatic amylase.
To study the diets of ancient dogs in greater depth, Losey and his colleagues analyzed the remains of about 200 of these animals and 200 wolves that lived within the last 11,000 years.
“We had to go to collections all over Siberia, we analyzed bones, we took collagen samples and studied the protein in the laboratories,” he said.
Based on the remains, the team made statistical estimates of the animals’ body sizes. They also used a technique called stable isotope analysis to estimate diets.
Scientists found that dogs from 7,000 to 8,000 years ago “were already quite small, which means they just couldn’t do the same things most wolves could,” Losey explained.
This has led them to become more dependent on humans for food and to hunt small prey rather than the larger hunts carried out by wolves.
Dogs at that time ate “fish, shellfish, seals and sea lions, which they cannot easily obtain on their own,” he said. They ate fish “in areas of Siberia where lakes and rivers were frozen for seven to eight months of the year,” she added.
While the wolves of those times, as well as the current ones, hunted in packs and ate mainly species of deer.
advantages and challenges
The new diets provided dogs with both benefits and challenges. “Advantages because they could access human food, easy at first, but at the cost of new diseases and problems,” Losey noted.
While the new bacteria and parasites they were exposed to may have helped some of them adapt, it’s possible that entire populations of dogs didn’t survive.
Most of the first dogs in the Americas went extinct, for unclear reasons, and they were replaced by European dogs, although colonization is not blamed for this process.
The dogs that survived acquired more diverse gut microbiomes, which helped them digest more of the carbohydrates associated with living with humans.
