Dogs are descended from at least two distinct populations of wolves.

The current dog comes from at least two populations of wolves. / Jessica Rae Peto

Science | Genetics

The analysis of 72 wolf genomes from the last 100,000 years suggests that their domestication could have occurred in Eastern Europe

Where does the dog come from? Scientists know that at least 15,000 years ago, during the Ice Age, humans domesticated the wolf ('Canis lupus'); but not where or if the process took place once or several times. An international team of geneticists and archaeologists says in the journal Nature that dogs (Canis lupus familiaris) descend from at least two distinct wolf populations and that domestication may well have occurred in eastern Eurasia.

Anders Bergström, from the Francis Crick Institute's Laboratory for Ancient Genomics, and his collaborators have analyzed 72 wolf genomes that have lived in Europe, Siberia and the Americas in the last 100,000 years. They correspond to animals recovered by archaeologists from sixteen countries. The oldest come from Eastern Siberia and the most recent from Europe and North America.

Only 6 genomes – all Siberian – had been published, while 66 have been sequenced for this work by nine laboratories. The remains analyzed include a perfectly preserved Siberian wolf head from 32,000 years ago and a two-month-old cub that lived 18,000 years ago known as Dogor ('friend', in Yakut), whose DNA has not allowed to determine if it is a wolf or a dog.

Dogor, a two-month-old puppy who lived 18,000 years ago. /

Sergey Fedorov

Researchers have found that both primitive and modern dogs are genetically more similar to ancient wolves from Asia than to those from Europe, suggesting domestication in eastern Eurasia. They have also found evidence that dogs are descended from two populations of wolves. The first dogs from northeastern Europe, Siberia and America seem to have a single oriental origin. However, the ancient dogs of the Near East, Africa, and southern Europe also appear to be descended from Near Eastern wolves.

100,000 years of natural selection

"We found that dogs derive from at least two separate wolf populations: an eastern source that contributed all dogs and a western source that contributed some dogs," says Bergström. According to the authors, there are two possible explanations for this double origin: that the wolf was domesticated several times and the resulting dog populations mixed, or that it was domesticated only once and the primitive dogs then mixed with wolves.

As the 72 wolf genomes span some 30,000 generations, the researchers have been able to see how the species' DNA has changed over time. They have thus seen that, between 40,000 and 30,000 years ago, a genetic variant of chromosome 25 went from being very rare to being in all wolves, and today it is in all wolves and dogs. It affects a gene that is involved in the development of the skull and jaw bones. The authors believe the spread of this variant may have been driven by a change in available prey during the Ice Age, giving wolves with a certain head shape an advantage, but they caution that the gene could also have unknown functions.

"This is the first time that scientists have directly followed natural selection in a large animal over a 100,000-year timescale, seeing evolution unfold in real time rather than trying to reconstruct it from current DNA." says Pontus Skoglund of the Francis Crick Institute's Ancient Genomics Laboratory and one of the authors. The researchers believe that the rapid spread of mutations to all wolves was due to “the species being highly connected across great distances. This connectivity is perhaps one reason wolves survived the Ice Age while many other large carnivores disappeared."

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