26 November 2021
Modern horses emerged from Western Eurasia
Published online 21 October 2021
An extensive genetic analysis concludes that the ancestors of modern-day domesticated horses originated in the western Russian steppes.
A long-standing debate about the origins of domesticated horses has been resolved, according to a multidisciplinary team of researchers ranging from archaeologists and geneticists to linguists.
“We map out the homeland of modern domestic horses to the Don-Volga region around 4,200 years ago,” says molecular archaeologist, Ludovic Orlando of Paul Sabatier University, in Toulouse, France. Orlando collaborated with more than 150 co-authors, including researchers at King Saud University in Riyadh, Saudi Arabia.
“Our Saudi colleagues were key to facilitating access to some specimens and to help understand and interpret some complex patterns in the DNA sequence data,” says Orlando.
Researchers have known for some time that modern domestic horse breeds are not descended from the earliest known domesticated horses, leading to much speculation about their true origins.
Orlando and his colleagues analysed horse remains from all suspected domestication centres throughout Europe and Asia. Their samples spanned a huge date range from around 2,000 years ago to more than 50,000 years earlier. The team performed DNA sequence analysis on 264 ancient genomes extracted from the remains, adding to the mix 10 modern genomes and 9 previously characterized ancient genomes. Overall, they say their dataset is “the most extensive high-quality genome time series for horses.”
The conclusions confirm some previous models proposing that modern horses originated in the western Russian steppes, while rejecting previously suggested origin sites in other regions such as Anatolia, Iberia and Central Asia.
“One important surprise was the timing of the expansion to after 4,200 years ago,” Orlando says. He explains that this is later than some genetically documented major human migrations, implying that horseback riding did not drive those earlier expansions
The work reveals that modern domestic horses eventually replaced almost all other local horse populations as they expanded rapidly across Eurasia. They also find that expansion was linked to strong selection for locomotive and behavioural adaptions suited to the needs of equestrianism. The researchers now plan to further explore such links between horse evolution and human societies.
Harvard University anthropologist, Christina Warinner, who was not involved in the work, comments: “This is an outstanding study, and it helps to clarify and answer so many long-standing questions about horse domestication. However, now that the homeland of domesticated horses has been identified, the next question is why there and why then? I suspect horses still have a few more secrets to tell.”
Librado, P. et al. The origins and spread of domestic horses from the Western Eurasian steppes. Nature https://doi.org/10.1038/s41586-021-04018-9 (2021).