Researchers Identify Ancestral Mother of Modern Horses

"Equine Eve," the ancestral mother of all modern horses, probably lived about 140,000 years ago, according to new mitochondrial genome research by Italian geneticists on a large population of modern horses. This research might someday help breeders identify athletic potential in horses, the researchers noted.

Humans began domesticating this wild mare's descendants well over a hundred thousand years later in multiple domestication sites across the planet, said Alessandro Achilli, PhD, assistant professor of Genetics in the Department of Cellular and Environmental Biology at the University of Perugia, Italy.

Although there is no physical evidence of this "equine Eve," genetic investigation and calculations based on the mitochondrial genomes of 83 modern horses throughout the world, provide a fairly reliable estimation of her existence, Achilli said. 

"We were able to reconstruct the Ancestral Mare Mitogenome (AMM), representing the mitochondrial DNA (mtDNA) of the most recent common female ancestor of modern horses," he said. "Then, by counting the number of differences between this ancestral mtDNA and the mtDNAs of modern horses we were able to establish when this ancestral mare was living." Unlike previous studies, Achilli's research focused on a more complete mitochondrial analysis, as is done in human genetic research, he said. 

The mtDNA of the modern horses in the study, which involved a wide variety of breeds and geographies—from the American Paint Horse and Chincoteague pony in the Americas, to the Trakehner and Clydesdale in Europe, to the Akal-Teke and Przewalski in Asia—could be divided into approximately 18 subcategories according to their haplotypes (classifications of the mtDNA based on close similarities of certain segments of the genome). 

The presence of these different "haplogroups" suggests the horses descended from separate lines, which is likely the result of domestication occurring about 10,000 years ago during the Neolithic period, Achilli said. In all, there were probably 17 different sites of domestication, mostly in Eurasia; the 18th haplogroup represents the Przewalski, which has never been domesticated but is still categorized as a modern horse.

More lines than these 18 haplogroups probably descended from the "equine Eve" but were lost due to severe climatic conditions over the past 140,000 years, he added.

The findings not only provide greater insight into the history of the horse, but in the future could also help breeders identify potential in racehorses, according to Achilli. "Mitochondria are the power generators of cells, and mtDNA (is) implied in energy production," he said. "(This could be) the first case of a 'measurable' genetic component related to performance variability, an innovative selection criterion for broodmares."

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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