Domestic dogs are probably descended from two lines of wild wolves.
Scientists analyzed the ancient DNA of wolves, which was stored in permafrost for tens of thousands of years, and were able to shed light on the process of dog domestication. This analysis showed that humans domesticated these animals twice, Science Alert reports.
All dogs in existence today, from the tiny Chihuahua to the mastiff, belong to one species, Canis familiaris. And they all descend from a common ancestor of wolves, including the modern gray wolf, Canis lupus. But the time frame of domestication is debatable. Some scientists suggest that this process began 100,000 years ago.
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In the course of preliminary work, scientists studied DNA samples of 32 dogs, whose age is 100-32 thousand years. They found that dogs diversified 11,000 years ago, so domestication must have started earlier. It is known that domestication began between 40 and 20 thousand years ago. Probably, this process took place more than once and in different parts of the world.
In the new work, the researchers studied 72 genomes of wolves, whose age was up to 100 thousand years. They covered about 30 thousand generations of wolves in Europe, Siberia and North America. These genomes were compared to 68 genomes of modern wolves, ancient and modern dogs, and other canine species such as coyotes.
The analysis showed that both ancient and modern dogs have more in common with the ancient wolves of Asia than with those that lived in Europe. This suggests that domestication and diversification may have started in the East, not the West.
But the researchers also found something strange. Early dogs in northeastern Europe, Siberia, and the Americas derive 100% of their DNA from eastern wolf populations. Early dogs from the Middle East, Africa, and southern Europe have wolf DNA related to modern populations in Southeast Eurasia.
This supports earlier findings that dogs were domesticated more than once. But it could also mean that dogs were first domesticated in the East and then interbred with wild wolf populations. At the same time, which of these scenarios is reliable, it has not yet been possible to determine.
The study also allowed scientists to learn more about the evolution of wolves. In particular, they found that the variant of the IFT88 gene has changed from very rare to common over the past 10,000 years. It is responsible for the development of the bones of the head and jaw, and is still present in almost every dog or wolf.
Currently, scientists cannot say why this mutation became so common. It may be due to natural selection: the types of food available have made the changes caused by the mutation particularly beneficial. It is also possible that this gene is responsible for some processes not yet known to scientists, which makes the mutation even more significant.
Previously, scientists found out that ancient European dogs between 8000 and 2000 years ago became twice as large. Thanks to this, they could protect livestock from wolves and bears.
