Scientists have shed new light on the origins of the domestic horse. After analysing DNA samples from both ancient and modern horses, researchers have concluded that contemporary horses do not have a single ancestry, but were probably domesticated from several distinct ancestral populations.
Scientists have shed new light on the origins of the domestic horse. After analysing DNA samples from both ancient and modern horses, researchers have concluded that contemporary horses do not have a single ancestry, but were probably domesticated from several distinct ancestral populations.
The German/UK research team included three Cambridge archaeologists. The team extracted mitochondrial DNA (mtDNA) - a type of DNA inherited from the mother and often used to study the evolution of species. mtDNA accumulates mutations at a steady rate, acting as a "molecular clock" for a species, and allowing maternal ancestry to be traced. The study analysed mtDNA samples from 25 different breeds of horses, and compared it with previously published DNA sequences from other horse breeds.
The researchers determined that the domestication of at least 77 different wild mares was required to produce modern domestic horses. The extensive genetic diversity of these 77 ancestral mares led the team to conclude that several populations of wild horses were involved in domestication.
"We see traces of original wild populations of horses that have been incorporated into the domestic horses of today," says co-researcher Dr Peter Forster of the McDonald Institute for Archaeological Research.
He believes it resolves the debate over whether horses were domesticated from one world population or from several.
"The genetic evidence shows that wild horses were recruited for domestication from different areas of the world. A single, simple origin of horse domestication can be ruled out," he explains.
It is not clear when domestication took place - there are claims for horse domestication as early as 4500BC, but the earliest undisputed evidence is from the Ural Steppe in 2000BC. Another question yet to be settled is how domestic horses spread: did one human population spread the techniques of domestication across continents, taming native horses as they travelled; or was domestication achieved by different groups in different places? The researchers hope that more detailed investigation will answer these questions.
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