The Ancient Roots of Arctic Sled Dogs | The Independent

Jhere are two great stories about dogs and humans. One is that of a deep and meaningful partnership between two species that ensures the survival of both. The other is that of scavengers and camp supporters who live off our waste and feed on our corpses in the shadow of war.

Both are undeniably true, in different places and times, but vast mysteries remain about the earliest roots of dogs and humans, and when the first glimpses of the working partnership appeared.

A team of 35, including a who’s who of ancient DNA experts, has now uncovered a vivid, genetically detailed picture of the oldest known case of selective breeding, the creation of Arctic sled dogs at least 9,500 years ago. years.

At that time, researchers discovered that sled dogs already had mutations in genes involved in oxygen utilization and temperature sensitivity that set them apart from other dogs and wolves.

And much of this genetic heritage survives in modern Greenland sled dogs. Other Arctic breeds, such as Alaskan Malamutes and Alaskan and Siberian Huskies, also carry some of this heritage, but not as much as Greenland dogs.

Mikkel-Holger S Sinding of the University of Copenhagen, one of the project’s lead researchers, says the genome of an ancient Siberian dog, an even older wolf, and some modern dogs provided “the first evidence tangible evidence of the early diversification of dogs”. He and his colleagues published their findings in Science.

Elaine Ostrander, who studies canine genetics and breed differences at the US National Institutes of Health and was not involved in the research, says it’s no surprise that dogs were bred in such a way selective 9,500 years ago. They were first domesticated at least 15,000 years ago. But, she says, the new research is the first “where someone put it all together and said, you know, this was 10,000 years ago.”

Terrie M Williams of the University of California, Santa Cruz, who studies the exercise physiology of carnivores, says researchers have tried to understand why sled dogs perform better than other breeds over long distances, by examining body shape and running mechanics. But they didn’t find the major differences they expected.

She says she’s thrilled to see that researchers have found specific genetic differences that set sled dogs apart. “That’s what’s so cool here,” she says.

Sled dogs have well-known roots in human prehistory. A 12,500-year-old tool found at an arctic site hints at its possible use on sleds. And archaeological digs at a well-known site on the island of Zhokhov in the Siberian Sea have unearthed dog bones and sled technology indicating dogs may have been the first canines bred for a specific task. .

Sinding and his colleagues dug deep into the DNA of one of these dogs, using a jawbone from the site dating back to 9,500 years ago. They also sequenced the genomes of a 33,000-year-old Siberian wolf and 10 modern Greenland sled dogs. They also relied on other canine genomes archived in databases.

They found that the Zhokhov dog was closest to modern sled dogs, specifically Greenland sled dogs, which are a “land breed”, bred for a task and sharing one appearance and behavior, but not the type of breed for which the records are. preserved.

In other words, if you have a malamute or a husky, don’t start parading around with your animal claiming its breed dates back 9,500 years.

The Zhokhov dog was not a direct ancestor of modern sled dogs, but it shared a common ancestor with modern sled dogs that was probably around 12,000 years old. This evidence suggests that the type of sled dog, bred to carry loads in harsh winters, was already established 9,500 years ago.

The researchers also found that sled dogs, ancient and modern, did not show interbreeding with wolves, even though other modern dog breeds did, and that dog-wolf matings were known in Greenland in the 19th century. historical era. The results suggest that the hybrids may not have been very useful for pulling sleds.

Then researchers began looking for different genes in sled dogs from wolves and other breeds of dogs. They found several that made sense. One is involved in a variety of physiological functions, including calcium transport and temperature sensitivity. They don’t know exactly what it does in sled dogs, but they do know that several similar genes are different in mammoths, creatures of the cold, and elephants, animals of more temperate climates, suggesting some sort of adaptation to arctic life.

Dogs drive their sled along a trail at the end of the winter season in Greenland, 2006 (AFP/Getty)

(AFP via Getty Images)

Another gene that sets sled dogs apart from other dogs is involved in managing low oxygen conditions. It is also found in a group of humans, the Sea Nomads, who have been diving for thousands of years. This could, according to Sinding, contribute to the ability to cope with the extreme demands of long sled rides.

And finally, one might expect to find arctic dogs adapted to a different diet than, say, dogs from the Fertile Crescent or European farmlands. They have specific genes to deal with high fat intake, just like humans and bears that live in the Arctic. And they don’t have the same adaptations to starch digestion found in many other dog breeds.

Dietary adaptations were not present in the Zhokhov dog, indicating that sled dogs changed over time.

Sinding warns that although Greenland sled dogs and other Arctic breeds make a major genetic contribution, particularly in terms of important identified genes from ancient sled dogs, they are not the same.

Modern sled dogs and sled technology have their origins in the Thule culture, he says, which dates back 2,000 to 3,000 years ago. And Greenland’s sled dogs went through what’s called a bottleneck about 850 years ago when the population declined. That’s when the Inuit arrived, and they succeeded the Thule people in Greenland.

Modern Arctic breeds have a major contribution from sled dogs of 9,500 years ago, he says, but a gap exists between then and 3,000 years ago.

In other words, if you have a malamute or a husky, don’t start parading around with your pet claiming its breed dates back 9,500 years. A lot of his genes may come from those old sled dogs, but as Sinding points out, “in principle, all dogs are the same age.”

© The New York Times

Bette C. Alvarado