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New enigma about the beginnings of livestock

An investigation has succeeded in sequencing the oldest mitochondrial genome of the immediate ancestor of modern cows analyzed to date. The remains, some 9,000 years old, appeared next to a woman. Why were they going with her, if the cattle had not yet been tamed?

The relationship of the human being with the Uros (Bos primigenius) was very close from the beginning, first hunting them and later, breeding and selecting them.

This extinct species of mammal is little known in the Iberian Peninsula because its skeletal remains are difficult to distinguish from the remains of bison. In fact, in many sites the presence of “large bovids” is cited as it is not possible to differentiate them. At the European level there is also a dearth of genetic data.

An international team of specialists, which includes scientists from the University of A Coruña in Spain, has managed to extract mitochondrial DNA from ruminants from various eras in Galicia. Among them they have analyzed remains of B. primigenius from the Chan do Lindeiro cave (Lugo, Galicia, Spain). These remains were found in a chasm together with the human fossils of the shepherd of O Courel “Elba”, with a dating of about 9,000 years old. The analyzed uros are not the oldest discovered, but they are the oldest whose mitochondrial DNA has been sequenced so far. Interestingly, although they were found together, they are genetically very diverse.

“His finding in the chasm along with a human is a great enigma. Given all the evidence, such as its similar chronology and the fact that the bones are intermingled at the base of a collapse due to the subsidence of the ground – at about 15 o 20 meters deep -, we think that the woman and the uros went together. This interpretation is controversial because at that time it is not considered that there was domestication “, explains Aurora Grandal, researcher at the University of A Coruña and co-author of the study that publishes the academic journal PLoS ONE.

Artistic reconstruction of the shepherdess Elba accompanied by the three aurochs found at the site and whose mitochondrial DNA has been analyzed. (Image: José Antonio Peñas (SINC))

The analysis of their mitochondrial DNA has not made it possible to relate these three uros with the current modern cows of the Peninsula. To investigate this possible relationship, the next thing the research team wants to do is analyze the nuclear DNA.

Until now, different varieties of aurochs have been described, just based on their morphology. The three that have been analyzed in this work are from haplogroup P, characteristic of the species. However, they differ from each other in a large number of base pairs (pieces that make up the genetic sequences), something striking for being contemporaries. “This may indicate that they were from different origins, in a scenario in which the Elba woman had an active role; or a trait that simply reflected a very high genetic variability in the Uros”, says the researcher.

Domestic cattle were introduced to Spain by the first settlers and agricultural societies. Due to the absence of Neolithic sites in Galicia, very little is known about the process in this region.

To extract information about the introduction of this livestock in Galicia, the researchers took samples of 18 fossils of cattle from different ages and from different Galician mountain caves, of which eleven were subjected to mitochondrial genome sequencing and phylogenetic analysis. .

The study of the three aurochs revealed their kinship with those from other areas of Europe. “By studying their mitochondrial DNA, which is transmitted almost intact from mother to child, we can determine in which geographical areas the different lineages predominated and what were their movements due to the change in climatic conditions or by the human being after the beginning of the disease. livestock “, explains the paleontologist and veterinarian Amalia Vidal, co-author of the work at the same university.

Thanks to the DNA, it is possible to know if the autochthonous aurochs contributed to the local livestock or, on the contrary, if they are imported animals, “with all the information that this provides about the movement of bovine and human populations”, continues Vidal.

Their data show a close relationship between the first domesticated cattle in Galicia and modern cow breeds, and offer an overview of the phylogeny of cattle. The results of the study indicate that settlers migrated to this region of Spain from Europe and introduced breeds of European cows now common in Galicia.

“Specifically, these aurochs are more closely related to that of the British Isles than to the Central European specimens. The British aurochs are more recent than those of Galicia. This may be related to the role of the Peninsula as a glacier refuge and the origin of later recolonization. of the islands, “says Grandal.

These three contemporaries are small in stature and relatively short horns compared to northern Europe, and their morphology is different.

Now, the team of researchers seeks to analyze the nuclear DNA of the three aurochs, which will allow them to know the possible contributions of these individuals to subsequent domestic livestock. “For example, in some breeds of cows from northern Europe fragments of nuclear DNA from British aurochs can be recognized. This shows that there was a genetic contribution of aurochs to domestic cattle. We are going to look for possible contributions of our aurochs to the Iberian cows, current or fossils “, underlines Grandal.

In recent years there is a growing interest in the scientific community to know the origin of domestic animals and there are many projects to reconstruct their ancestors. One of the reasons is that these species are considered more rustic and with a better capacity to adapt to harsh environmental conditions.

“The first projects sought to generate phenotypes similar to the species they were trying to recreate (as was done with Heck’s bovine), but the most modern also use DNA as a source of information”, concludes Vidal.

The social organization of the uros herds is supposed to be similar to that of their domesticated bovine descendants: a single male who is relieved by another as he weakens and his group of females.

The new males, when they reach adulthood, do not remain in the group, the females do. In this way, the normal thing is that the females of the same group are related and that, therefore, their mitochondrial lineages are similar.

The domestic cow comes from the domestication of the aurochs, but not in the Iberian Peninsula but in Asia, specifically in the Middle East and from a small number. Thus arose the domestic cow, which later expanded along with humans to occupy all of Europe.

In Italy, some researchers claim that cows already domesticated had genetic contributions from local aurochs. Also in the British Isles. The contribution of local uros to cows is best seen in nuclear DNA and was detected in some cases of northern European breeds.

In the north of the peninsula, the oldest domestic cows are between 7,000 and 6,000 years old. (Source: FECYT / SINC)

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