Genomic analysis has allowed scientists to track the process of equine domestication, identifying changes in DNA over time.
Previous studies pinpointed the first stages of the taming of wild horses to the steppes of Eurasia around 5,500 years ago. Evolutionary geneticists have long wanted to understand the associated genetic changes because of the great influence that horses had on the development of early civilizations.
The introduction of horses as a method of transport led to wholesale changes in trade and warfare, as well as the movement of people and ideas. The development of large empires such as the Scythians has also been attributed, at least in part, to the domestication of wild horses.
DNA changes in domesticated horses
This latest study, led by geneticist Ludovic Orlando of the Natural History Museum of Denmark, says that 125 genes are responsible for equine domestication. Mr. Orlando claims that the genes are “related to skeletal muscles, balance, coordination, and cardiac strength, they produced traits so desirable that ancient breeders selected horses for them,”
Other genes linked to social behavior, fear response, humor and learning are also more common in domesticated horses.
In order to understand how horses were domesticated, scientists compared tamed species to their wild cousins. Without any wild horses to study, the team compared the DNA of 5 modern domesticated horses to the DNA from 29 horse bones recovered from Siberia. The bones date from 16,000 and 43,000 years ago.
Certain genes present in modern horses were not present in ancient ones, meaning that they are the product of relatively recent mutations. One example is a short-distance “speed gene,” particularly important for horses bred for racing.
A point of contention
The study has provoked opposition from others in the genetics community, who claim that analyzing DNA from the time of domestication, rather than from ancient horses, would lead to more accurate results.
“Comparing ancient genomes to modern genomes is tricky,” said Arne Ludwig of the Leibniz Institute for Zoo and Wildlife Research in Berlin. If scientists can find a source of DNA from around 5,500 years ago, it would further improve our understanding of the process of equine domestication.
The full study was published in the journal Proceedings of the National Academy of Sciences this week.