Five Dog Lineages

In a new study published in the journal Science, an international team of scientists sequenced the genomes of 27 ancient dogs, some of which lived up to nearly 11,000 years ago, across Eurasia. The researchers found that dogs likely arose once from a now-extinct wolf population and that by 11,000 years ago, at least five major ancestry lineages had diversified, demonstrating a deep genetic history of dogs during the Paleolithic.

Bergström et al. presents evidence that there were different types of dogs more than 11,000 years ago in the period immediately following the Ice Age. Illustration by John James Audubon John Bachman.

“The dog is the oldest domesticated animal and has a very long relationship with humans,” said co-lead author Dr. Anders Bergström, a researcher in the Ancient Genomics Laboratory at the Francis Crick Institute.

“Therefore, understanding the history of dogs teaches us not just about their history, but also about our history.”

“We examined dogs from across the old world, and they represent a period that stretches almost 11,000 years back in time,” said co-author Professor Anna Linderholm, an archaeologist at Texas AM University.

“The dog samples have been gathered from museums, and other collections from across the world and by several members of the team.”

“Since we don’t know when and where dogs were domesticated, we have collected most of the known dogs from the old world, going back as far in time as possible and using dog DNA that has been best preserved.”

The scientists sequenced 27 ancient dog genomes up to 11,000 years old from Europe, the Near East, and Siberia.

To test the association with human population history, they compiled 17 sets of human genome-wide data that matched the age, geographic location, and cultural contexts of the ancient dogs, and they directly compared genetic relationships within the two species.

They found that all dogs share a common ancestry distinct from present-day wolves, with limited gene flow from wolves since domestication but substantial dog-to-wolf gene flow.

While the precise timing and location of domestication remain elusive, the results indicate that at least five major dog lineages had already diversified and spread worldwide by 11,000 years ago, suggesting a considerable genetic history during the Paleolithic.

Ancestry of global dogs today: (A) for each present-day population, the ancestry proportions estimated by the best-fitting qpAdm model, restricted to models containing up to four of seven selected sources, are displayed; populations for which a single component accounts for over 98% of the ancestry are collapsed to smaller circles; (B) illustrations of inferred population histories in three regions of the world. Image credit: Bergström et al., doi: 10.1126/science.aba9572.

“The five linages from over 11,000 years ago is more diversity than we have been able to identify before,” Professor Linderholm said.

“Having said this, all dogs seem to have originated from one ancient wolf population, a wolf population that has since disappeared.”

“We have no connection with our modern-day wolf populations with our first domesticated dogs.”

“Some of the variation you see between dogs walking down the street today originated in the Ice Age,” said co-lead author Dr. Pontus Skoglund, a scientist in the Ancient Genomics Laboratory at the Francis Crick Institute.

“By the end of this period, dogs were already widespread across the northern hemisphere.”

“Dogs are our oldest and closest animal partner,” said co-lead author Dr. Greger Larson, Director of the Palaeogenomics and Bio-Archaeology Research Network at the University of Oxford.

“Using DNA from ancient dogs is showing us just how far back our shared history goes and will ultimately help us understand when and where this deep relationship began.”

“Just as ancient DNA has revolutionised the study of our own ancestors, it’s now starting to do the same for dogs and other domesticated animals,” said co-lead author Dr. Ron Pinhasi, a researcher at the University of Vienna.

“Studying our animal companions adds another layer to our understanding of human history.”

“The human-dog bond can now be seen a bit more clearly. When humans moved, they almost always took their dogs with them,” Professor Linderholm added.

“We see this happening when farming was introduced into Europe and other areas such as the Steppes in Asia.”

“We note a clear link between the movement of people and the introduction of a new type of dogs. This is new, and we also don’t see this pattern repeating itself when we have another large population movement.”

“So humans were not always consistent in their actions at this time, but we do see a much greater connection between humans and their dogs, more so than any other animal.”

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Anders Bergström et al. 2020. Origins and genetic legacy of prehistoric dogs. Science 370 (6516): 557-564; doi: 10.1126/science.aba9572