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Wolf turned into dog both in the east and the west

Today’s dogs descended from two different wolf populations that were domesticated in East or Central Asia. Researchers have come to this conclusion after analyzing DNA from prehistoric wolves in the northern hemisphere. Dogs of African and European origin also have a certain heritage from prehistoric wolves in the Middle East in their DNA. The study was recently published in Nature.

”Since we can follow evolution over time by analyzing prehistoric DNA, we can see the common history of wolves and dogs,” says Love Dalén, professor of paleogenetics at the Swedish Museum of Natural History and Stockholm University.

Previous studies have shown that wolves were domesticated between 14,000 - 35,000 years ago, possibly even earlier.

In this study, researchers have begun to identify where it may have happened, and if it has happened in several places. By analyzing DNA in 72 prehistoric wolves from up to 100,000-year-old finds across the northern hemisphere - Europe, Siberia and North America - the researchers saw that dogs are most closely related to early wolves in East Asia, indicating that it was probably there that the domestication took place.

Two possible scenarios

A certain kinship is also seen between wolves in western Eurasia and both African and European dogs. This can be explained by two different scenarios. Either wolves have been domesticated even in the Middle East, or dogs in this part of the world have been mixed with wolves so that the dogs’ offspring have been supplemented by local wolves’ DNA.

None of the wolf populations in the research study match enough with dogs for the researchers to be able to say exactly where the domestication took place. But since all dogs have parts of their DNA in common with prehistoric wolves from East Asia, it is probably somewhere there the dogs’ origins are found. The difficulty of finding preserved DNA from southern, and thus warmer, latitudes than eastern Siberia means that finds from there are rare. But when more such finds are made, it could show which wolf population the first domesticated wolf belonged to.

”Dog DNA has a specific signature, so in the future we hope to be able to find the missing link, the wolf populations that would become dogs. Ancient wolf DNA is the key to solving the mystery of dogs’ unknown origins,” says Pontus Skoglund at The Francis Crick Institute.

The wolf’s head was reshaped by mutation

Wolves have been present throughout the northern hemisphere for hundreds of thousands of years. In the study, the researchers got a picture of the wolf’s evolution by comparing the DNA from wolf fossils with different ages. They saw that it was in Siberia that evolution had its engine and that a large gene exchange has taken place continuously between wolves all over the hemisphere. This great gene flow was possible thanks to an open landscape and the wolves’ long walks.

A mutation that probably changed the shape of wolves’ heads or jaws spread rapidly around the world about 40,000 years ago, and other mutations in olfactory receptors spread similarly. Today, these mutations are found in all wolves, including dogs.

”Thanks to the fact that we have DNA that extends over such a large time span, we can observe the natural selection directly, and identify favourable mutations. That some of these mutations spread so quickly to the whole species gives us a new understanding of the wolf’s evolution,” says Anders Bergström at The Francis Crick Institute.

The wolf survived the ice age

Unlike many other larger mammals, the wolf survived the last ice age. The researchers partly explain this with the large gene exchange which meant that wolves in different parts of the world were not isolated from each other. Today, however, the situation looks very different, with great isolation between different wolf groups and local extinction in many areas in, for example, Western Europe and South Asia. It is probably the spread of humans, with agriculture and industrialization, that has put strong pressure on wolf populations in recent centuries.

”The wolf seems to have coped well with the dramatic climate changes that took place during the end of the ice age, and did not meet the same fate as, for example, hyenas, lions and cave bears in Eurasia. The wolf probably has this to thank for its great mobility and ability to adapt to different environments,” says researcher Dave Stanton, Center for Paleogenetics.

The research group was led by Swedish researchers at both The Francis Crick Institute in London and the Center for Paleogenetics, which is a joint venture between the Swedish Museum of Natural History and Stockholm University.

Read the article in Nature: Grey wolf genomic history reveals a dual ancestry of dogs.