They accompanied the first people to set foot in the Americas.
Dogs tagged along with the first humans to venture into the Americas, according to a recent study that analyzed existing collections of canine and human DNA. The results suggest that people domesticated dogs sometime before 23,000 years ago in Siberia, where isolated groups of wolves and people were struggling to survive the Last Glacial Maximum.
A tail of two species
Researchers generally agree on how dogs evolved (more on that below), but the when and where have remained more elusive. Durham University archaeologist Angela Perri and her colleagues used genetics to try to narrow it down.
Because genomes collect small, random mutations at a predictable rate, geneticists can compare genome sequences and tell how long ago two animals last shared a common ancestor. Perri and her colleagues used already-sequenced genomes from ancient and modern dogs to calculate when populations had split or interbred, and then they repeated the process with human genomes.
Their results suggest that people in northern Siberia domesticated the first dogs sometime before 23,000 years ago.
Like several other recent genetic studies have recognized, Perri and her colleagues noticed that dog and human groups tended to split or merge in roughly the same times and places, creating a genetic map of our species’ shared journey. The timing of one of those splits, around 16,000 years ago, strongly suggests that the first people to enter the Americas brought dogs with them.
Did someone say W-A-L-K?
A major split in both dog and human populations happened between 16,000 and 15,000 years ago. Archaeological evidence tells us that at this time, people were making their way south along the Pacific coast of North America, traveling past the edges of the massive ice sheets that still covered most of the continent.
At the same time, a new branch of dogs split off from the Arctic dog population, which includes modern Siberian huskies. The branch is called haplogroup A2b, and it’s the maternal lineage of all indigenous North American dogs. Mitochondrial DNA from ancient and modern dogs suggests that the dogs of haplogroup A2b last shared a common ancestor with Siberian huskies around 16,400 years ago—about the time the first people were crossing the Bering land bridge and moving into North America. “The time frame is remarkably consistent with that of the first peopling of the Americas,” wrote Perri and her colleagues.
Sadly, you won’t find many dogs from haplogroup A2b in the Americas today.
“There are some dogs that have small amounts of those lineages, such as the Carolina Dog, or some Chihuahuas, but most dogs in the Americas today all genetically look like European breeds,” coauthor Kelsey Witt Dillon, a molecular biologist at Brown University, told Ars. “Similar to how many Native Americans were killed by Europeans through warfare and disease, their dogs were likely also targeted by European colonizers and died from diseases from European dogs,” she said. “And when Europeans brought their dogs with them in large numbers, European breeds eventually replaced a lot of the genetic lineages we see in these ancient dogs.” [ … ]