At least 15,000 years ago, towards the end of the last Ice Age, a pivotal event in human history occurred when wolves became the first species to create a domestic population: the dog. Numerous cultures and empires have risen and fallen since then, but one thing hasn’t changed: dogs – and now many other animals – continue to live with us across the globe, as science tries to get ever closer. at the beginning of this relationship.
There are still several mysteries surrounding the origin of dogs, although it is clear that they arose from the wolf. A study published this Wednesday by the magazine Nature, made from an exhaustive analysis of more than 70 samples of ancient wolf DNA, sheds new clues about this decisive moment in the history of the cnids … and humans. Today’s dogs, according to the new research, were born from two different populations of wolvesalthough they come to a greater extent from the ancestral wolves of Asia than from those of Europe.
The finding therefore suggests that the domestication of the dog may have occurred somewhere in the East. However, it is not all clear yet, since it has also been found that some dogs share another ancestor among ancient wolves, linked this time to the populations of the West. There are two possible explanations: either domestication occurred independently in various regions, and populations later mixed with one another; or else there was only an initial domestication, in the East, but some of the earliest populations of dogs continued to mix with wild wolves.
In any case, the double ancestry that the research has identified would have occurred. That is to say, the dog would descend from two different populations of wolves, an eastern one from which all current dogs come, and a more western one that also contributed its genes, but only to some dogs. On the other hand, the work offers valuable data on the evolution of the wolf during the Ice Age, a very convulsive time for the species, in which many of them disappeared. The survival of the wolf in those harsh times allowed its descendants to be domesticated and thus began a new kind of relationship between humans and other species.
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“First, our study provides new insights into the evolution of the wolf species over the last 100,000 years. We have found that, during the Ice Age, wolf populations in different parts of the world were very genetically connected, reflecting the great mobility of wolves around the world“, comments Anders Bergstrm, first signatory of the study and researcher at the Francis Crick Institute, in the United Kingdom, to EL MUNDO.
“We have also identified examples of natural selection, with beneficial new mutations rapidly spreading throughout the wolf species. These findings may help us understand how wolves survived the dramatic changes of the Ice Age, when many other mammals became extinct. High genetic connectivity surely helped local wolf populations avoid becoming fragmented and isolated from one another, and allowed new biological adaptations to reach the entire species,” continues Bergström.
“Second, our study takes an important step toward resolving the question of the origins of the dog. By studying ancient wolves that lived around the time of dog domestication, we have discovered that dogs in general are more closely related to the ancient wolves of Asia than to the ancient wolves of Europe, suggesting a domestication process somewhere in the East. But we have also discovered that some dogs, particularly those from Africa and the Near East, have an additional genetic contribution from a second population of wolves, one that is related to wolves in the West. Therefore, it seems that there are at least two different original populations of wolves that gave rise to a double ancestry in current dogs”, details the researcher.
However, some pieces of the puzzle remain to be discovered: “In this study we have taken important steps to understand how dogs fit into the evolutionary history of the wolf. In particular, by determining that there would have been two different original populations of wolves. But we have not resolved the geographic origins of these two populations with much precision geographic. This is because, in many parts of the world, we do not yet have any ancient wolf genomes. The search for original populations will therefore continue in future research, and will require extending the sample of ancient wolves into regions not covered in this study,” explains Bergström.
In fact, obtaining usable DNA samples from ancient species is quite a challenge: “Ancient wolf remains, which were mostly bones and teeth, were provided by a large number of zooarchaeologists who have participated in previous excavations and studies of the remains.” We then drill small holes into each specimen to obtain a small amount of bone powder, from which the DNA is extracted. It is the same technology used to study DNA in other species, including humans.. One challenge is that many remains do not have much preserved DNA, or none at all. A study like ours, therefore, requires analyzing many different remains, and being lucky with some of them that maintain good DNA preservation”, explains the first author of the study.
One of the institutions that has provided various samples has been the Doana Biological Station, attached to the Higher Council for Scientific Research (CSIC). “These samples are particularly
important, since the oldest wolf fossils have been found in the regions
southern Europe”, explains Jennifer Leonard, a researcher at the aforementioned center who collaborated in the study. “The problem is that it is quite difficult to obtain ancient DNA from these bones, due to
Andalusian climate favors the degradation of the genetic materialhe adds.
In total, 72 wolf genomes have been analysed, 66 of them obtained for the first time for this study, and which together cover the last 100,000 years. The samples come from Europe, Siberia and North America. By genetically tracing the history of the species for so long, equivalent to 30,000 generations, scientists have found evidence of natural selection. Specifically, they have seen a major mutation in the IFT88 gene that spread rapidly throughout all wolf populations about 30,000 years ago and that, surely, helped the species overcome the Ice Age.
“We know from studies in mice and humans that the IFT88 gene is involved in skull and jaw development. Although we can’t be sure why natural selection favored this gene in Ice Age wolves, we speculate that it might have reflected in some kind of morphological adaptation, perhaps in response to changes in prey availability or hunting strategies. Many species that were potential prey became extinct during the Ice Age. Changes in facial or jaw morphology, such as those conferred by IFT88 mutations, could have allowed wolves to adapt to new conditions during this ecologically tumultuous period,” says Bergström.
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