For years, archaeological evidence has led scientists to believe that the wild boar was domesticated in the Middle East some 10,000 years ago, and as such, that the wild boars that populate these countries today would tend to resemble domestic pigs throughout Europe. . But this is not the case . A new study from the University of Oxford in conjunction with Queen Mary University of London has found that, by contrast, pigs underwent a complete genetic restructuring in the years following their arrival in Europe.
This research, published in the Proceedings of the National Academy of Sciences , has made it possible to write a new timeline in relation to the origin of modern pigs: they are much more similar to the European wild boar that was already on the continent when they arrived there around 8,000 years ago. years, than the eastern wild boars from which they came.
Pigs lost ALMOST all their eastern ancestry
Although it is true that the first pigs that arrived in Europe, together with their farmers, at that time had a clear ancestry from the Middle East, over the next three thousand years, these ancient pigs were mixed with the European wild boar, of so that they came to lose almost all their oriental lineage.
Of course, the pigs did not completely lose their oriental ancestry, which is evident in the characteristic black color of the fur, or in the black and white spots in some of them. In the future, the goal will be to accurately identify the remaining (few) genes that retained their original Middle Eastern ancestry in the genome of modern European domestic pigs. This will allow us to assess whether the artificial selection applied by the first farmers more than ten thousand years ago left a legacy in modern pigs beyond coat color.
According to Dr. Laurent Frantz, lead author of the study at Queen Mary University of London: “Until now, it was believed that the big genetic change in the pig occurred in the initial process of domestication, but new data suggests that the first two fifteen hundred years of human selections have not been relevant in its evolution process ”, which would downplay the importance of human intervention in the characteristics of modern pigs.
On the other hand, not all pigs were mixed equally: the Mediterranean island pig populations maintained a higher level of eastern ancestry, probably because these populations experienced comparatively less gene flow with the European wild boar than those of the interior of Europe.
The replacement of almost the entire genome of pigs, in slow motion
The research team worked with sequenced DNA signatures from more than two thousand ancient pigs , including the genomes of sixty-three archaeological pigs from the Middle East and Europe over the last ten thousand years, as explained by Professor Greger Larson, Director of the Paleogenomics and Bioarchaeology Research Network at Oxford and lead author of the study, in a press release:
“Having access to ancient genomes in such a large space and time has allowed us to see ‘in slow motion’ the replacement of the entire domestic pig genome. This suggests that the domestication of pigs in Europe for thousands of years was extensive, and that although the pig farmers kept the selection of some coat colors, the domestic pigs interacted with the wild boar often enough to lose the ancestral signature of the eastern wild boar, from which they originated. “
An anonymous relative
In 2015, an international team of researchers already discovered that domesticated pigs in Europe have much more wild boar than previously thought. In their paper published in Nature Genetics , the team describes their genetic study of a large number of domestic pigs and wild boars in Europe and Asia.
The researchers also concluded that modern pigs are not the result of isolated reproduction, but are the result of crossing between domestic pigs and wild boars over the course of many years. What’s surprising about this study, and what the new research doesn’t address, is that some of those wild boar genes weren’t in the starting data set, suggesting they might have been from an unknown, now extinct species. .
Source: Laurent AF Frantz el al., Ancient pigs reveal a near-complete genomic turnover following their introduction to Europe , PNAS (2019). www.pnas.org/cgi/doi/10.1073/pnas.1901169116
