Old DNA reveals common history of sheep and humans

Old DNA reveals common history of sheep and humans

Vessel with two pockets from around 2600 to 2500 BC. © Norbert Shcimmel Trust, 1989/ Met Museum

Sheep has been serving us humans as farm animals for around 11,000 years. A study has now reconstructed the descent history of the sheep based on DNA up to 12,000 years old bones. The genetic information reveals numerous human influences. On the one hand, the hikes of our ancestors are also reflected in the genome of the sheep. For example, shepherd peoples from the Eurasian steppe brought their herds to Central Europe around 5,000 years ago. On the other hand, people apparently selected their herd animals early according to certain characteristics. For example, this explains why most sheep are white today.

With around 1.2 billion copies worldwide, sheep are among the most important farm animals of humans. In addition to meat and milk, they provide in particular wool from which our ancestors were able to produce warm, water -repellent clothing many thousand years ago. Earlier studies had already indicated that the sheep were originally domesticated in the fertile crescent moon more than 11,000 years ago, where Wilde Mufflons formed the starting population for the Neolithic herds. However, the exact history of the sheep was still unclear.

Genome from old sheep bones

A team led by Kevin Daly from Trinity College Dublin in Ireland has now reconstructed 118 genomes from sheep bones, which are up to 12,000 years old and come from all over Eurasia, from Mongolia to Ireland. Some of the oldest finds come from the Aşıklı Höyük settlement in Anatolia, where people and sheep lived side by side more than 10,000 years ago. “These genomes are genetically close to the origins of the house sheep, but do not completely explain the descent of later populations,” report Daly and his team.

When comparing with old sheep genoma from other parts of the world, the researchers found conspicuous parallels to human migration movements. 8,000 years ago, there were still clear genetic differences between the households in their anatolical area of ​​origin and the herds in Europe and East Asia. Later, however, the descent lines mixed. “The pronounced Bronze Age migration movement of the sheep from the Eurasian steppes to Europe coincides with what we know about human hikes in the same period,” explains Daly. “This indicates that when they move on, people took their herds with them.”

Targeted selection

In addition, the research team found evidence that our ancestors began to breed sheep about 8,000 years ago and to select them according to certain characteristics. “The genomic signatures indicate a selection of shepherds at the time in relation to fur color, horn formation and growth rate,” report the researchers. Especially in the case of a gene associated with the white fur color, Daly and his team found strong indications of a positive selection by humans. In the course of the cathedral history, the bright fur color was increasingly prevailing against the darker color of the wild and early sheep breeds.

“This indicates that the shepherds preferred certain fur colors,” explains the research team. Perhaps individual shepherds also deliberately breed animals with exceptional pigmentation in order to be able to better identify them in common herds. “An alternative explanation is that the pets had a strong symbolic and aesthetic value and the shepherds simply preferred the beautiful and unusual preferred,” said the researchers. Together with similar indications of goats, this is the earliest evidence that humans influenced the biology of animals in a targeted manner.

“Our study brings morphological and genomic evidence of the geographical origin of households in harmony,” says co-author Joris Peters from the LMU Munich. “But it also clearly shows that further transdisciplinary research is necessary to clarify the patterns of the spread and selection of the many landing breeds that are now widespread in Eurasia and Africa.”

Source: Kevin Daly (Trinity College Dublin, Ireland) et al., Science, Doi: 10.1126/science.adn2094

Recent Articles

Related Stories