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A genomic analysis A complete set of modern and ancient donkeys reveals the origins of this animal and its spread across the continents. The domestic donkeys (Equus asinus) have been important to humans for thousands of years, providing a source of work and long-distance transportation for many cultures, particularly in arid and semi-arid regions. However, very little is still known about their history, and when and where they were domesticated is a scientific mystery long lasting.
Now, a new study published in Science reveals that these creatures were domesticated in Africa and from there they spread like wildfire, reaching Europe and Asia in just a few centuries. The work is the result of collaboration between more than 30 institutions from various countries and has been led by researchers from the Paul Sabatier University of Toulouse.
Although currently undervalued −probably due to their loss of usefulness in modern industrialized societies−, donkeys continue to be essential for the development of low and middle income communities, particularly in semi-arid environments. Understanding their genetic history is important to assess their contribution to human civilizations, but also to improve their management in the future, the authors write.
Modern and ancient DNA study
The researchers sequenced the genome of 207 modern specimens and 31 ancientincluding 15 wild equids. “To understand genetic change over time, we analyzed the genomes of donkeys that lived in the past in a wide geographic region, from Western Europe until Central Asia”, tells SINC Evelyn Todd, researcher at the Center for Anthropobiology and Genomics of Toulouse CAGT and first author of the study.
The science team found strong evidence for a single event of domestication in East Africa more than 7,000 years ago (about 5,000 BC). This was followed by a series of expansions on that same continent and in Eurasia, where subpopulations eventually became isolated and differentiated.
The team estimates that the donkeys expanded out of africa at least 4,500 years ago (around 2,500 BC) and spread rapidly both to the east − through Asia − and to the west − in Europe − at a maximum of a thousand years. “The oldest genomes we studied were from West and Central Asia and provide evidence for an early expansion of donkeys out of Africa.”explains Todd.
“Through the analysis of ancient DNA, we also discovered the existence of a previously unknown genetic lineage in the Levant some 2,000 years ago. Although different from all the other donkeys included in the study, we identified traces of its genetic legacy in modern specimens throughout Eastern Europe, Central and East Asia”says Todd. The researchers suggest that this lineage contributed to increasing ancestry toward Asia.
Donkeys in the Roman Empire
The expansion of the donkeys, however, did not follow a single direction and later returned to Africa. Already in the Roman age these animals were exchanged between Europe and Africa across the sea Mediterranean. Although these exchanges continued after the collapse of the Roman Empire, they left the most important genetic imprint on modern West African specimens.
According to the scientists, the breeding of donkeys then implied inbreeding −inbreeding− for the production of giant Bloodlines, at a time when mules were essential to the economy and military of the Roman Empire. Mating between these giant donkeys and female horses made it possible to produce sterile mules, which were an important source of animal labor.
Here, the genetic evidence it echoes texts from Roman times describing that selective breeding of animals of exceptional stature was already a common practice and lucrative business at the time. “This is the power of ancient DNA: to provide data that can test hypotheses from other classical historical sources, comments Ludovic Orlando, CAGT researcher and lead author of the research.
This work clarifies global patterns of donkey domestication and movement around the world, but also highlights many directions for Future investigations, the authors write. “Improve the archaeological record Africa today will allow us to refine our understanding of the genetic history of these animals and their relationships with humans over time.”Todd concludes.
Font: Iole Ferrara / SINC Agency
Reference article: https://www.agenciasinc.es/Noticias/La-domesticacion-del-burro-happened-en-Africa-7,000-years-ago
