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An international team of researchers, with the participation of UAB professor, Jordi Jordana, has published in Science magazine the results of their investigation into the origins of the domesticated donkey. The authors have discovered by using genetic analysis that the domesticated donkey originated in northeastern Africa approximately 5,000 years ago, quite probably due to the desertification of the Sahara. The conclusions of the study state that all domesticated donkeys come from two different lines from northeast Africa.
Donkeys were the last species of domestic livestock (cows, sheep, goats, horses, pigs, etc.) to be domesticated. Archeological evidence suggests that they were domesticated some 5,000 to 6,000 years ago. However, there was no solid evidence of where their domestication may have taken place. The majority of species were first domesticated in the Near East (Mesopotamia, Asia Minor, Iraq, etc.) and southwest Asia (the Arabian Peninsula), so it may seem logical that that the same occurred in the case of donkeys. Nevertheless, based on the genetic data of 259 domesticated donkeys from 52 countries, the team of researchers arrived at an unexpected conclusion: the closest relatives to present day domesticated donkeys are the wild asses of northeastern Africa, i.e., Nubian wild asses, (E.a.africanus) and the Somalian wild ass (E.a.somaliensis)
The scientists have also discovered the number of domestication events that took place. The study of the domestic populations places these individuals in two large groups with a high level of divergence (of the sequences of mitochondrial DNA) between them, which would suggest two different origins. Thus, the phylogenetic analyses indicated the existence of two divergent maternal lineages, which implies two domestications. The separation of these two lineages coming from a hypothetical common ancestral line took place between 303,000 and 91,000 years ago, a time quite earlier than the first domestication events of other livestock species, which corroborates two different maternal origins for domesticated donkeys from two different wild populations.
To locate the specific area of the first domestications, the researchers studied the genetic diversity. The northeast African animals retained, in a very significant way, greater diversity. The scientists have deduced that the ass is the only hoofed livestock species domesticated exclusively in Africa.
The study also demonstrates that the practice of domesticating animals, which first occurred in the Near East between 10,000 and 12,000 years ago, reappeared 5,000 years ago in northeastern Africa, probably as a response to the desertification of the Sahara (between approximately 5,000 and 7,000 years ago).
The investigation supports the idea that the asses were transported, moved and intensely commercialized. This could shed light on the role of the northeastern African region in human migrations and commerce. The study could contribute new clues that will redirect future archaeological studies to approach new evidence on the origins of animal domestication.
Other participants in the research were: Albano Beja-Pereira, of the University of Porto (Portugal), who was the study director; Phillip R. England, Pierre Taberlet and Gordon Luikar, of the Joseph Fourier University in Grenoble (France); Nuno Ferrand, from the University of Porto and the Praça Gomes Teixeira Faculty of Sciences (Portugal); Steve Jordan, of Bucknell University (U.S.A.); Amel Or Bakhiet and Mohammed To Abdalla, from Sudan University of Science and Technology (Sudan); Marjan Mashkour, from the National Natural History Museum (Frankfurt).
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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