Many dog owners may not be surprised to learn that most dogs still carry some wolf DNA in their genomes. Domestication has changed dogs dramatically from their wolf ancestors, but most do still have some small but detectable remnants of their wild ancestry. The wolf genes that can be found in dogs seem to influence a variety of traits, such as scent ability, body size, and some behavioral characteristics. Wolf ancestry is found at different levels in a variety of dog breeds, from Shiloh shepherds to chihuahuas. The findings have been reported in the Proceedings of the National Academy of Sciences (PNAS).
"Modern dogs, especially pet dogs, can seem so removed from wolves, which are often demonized," said lead study author Audrey Lin, a Gerstner Postdoctoral Scholar in Bioinformatics and Computational Biology at the American Museum of Natural History. "But there are some characteristics that may have come from wolves that we greatly value in dogs today and that we choose to keep in their lineage. This is a study about dogs, but in a lot of ways, it's telling us about wolves."
It’s generally thought that about 20,000 years ago, dogs emerged from a now-extinct group of grey wolves that lived alongside humans. Wolves and dogs still have things in common; they share territory, and can even generate viable offspring. But they don’t typically hybridize, and once separate lineages of wolves and dogs were established, there seem to have been very few events where they mixed again.
"Prior to this study, the leading science seemed to suggest that in order for a dog to be a dog, there can't be very much wolf DNA present, if any," Lin said. "But we found if you look very closely in modern dog genomes, wolf is there. This suggests that dog genomes can tolerate wolf DNA up to an unknown level and still remain the dogs we know and love."
In this study, the researchers assessed over 2,700 genomes in databases maintained by National Center for Biotechnology Information and the European Nucleotide Archive. This data included DNA from wolves, breed dogs, village dogs, and other types of canids, and spanned DNA samples that are as much as 20,000 years old, to modern samples.
The work showed that about two-thirds of breed dogs have detectable wolf ancestry in their genomes from hybridization events that happened roughly 1,000 generations ago.
The highest levels of wolf ancestry were found in wolf-dog hybrids like Czechoslovakian and Saarloos wolfdogs, who carried 23 to 40% wolf DNA. But the highest in typical dog breeds was seen in the great Anglo-French tricolor hound with 4.7 to 5.7%. Next was the Shiloh shepherd with 2.7%. Higher levels of wolf ancestry were seen in some larger dogs and those bred for specific duties, like Arctic sled dogs or hunting dogs. They also tended to be described with words like "alert," "loyal," "reserved," "suspicious of strangers," "dignified," and "territorial."
Terriers and scent hounds had lower levels of wolf ancestry, but the chihuahua still carries a bit of wolf ancestry: 0.2%. Those with lower wolf ancestry levels tended to be described more like "affectionate,” "friendly," "eager to please," and “easy to train," for example.“Intelligent," "calm," "cheerful,” "obedient," "good with children," and “dedicated," were seen with similar frequency in both groups.
“What we've found is that this is the norm most dogs are a little bit wolfy," Lin said.
Sources: American Museum of Natural History, Proceedings of the National Academy of Sciences