16-05-2025
Horses were running between Asia, North America 50,000 years ago: study
Ancient horses repeatedly migrated between North America and Eurasia, reaching today's Russian Far East near China, during the late Pleistocene when sea levels dropped and a land bridge connected the two continents, a new study found.
Among the studied fossils are Dalianensis horses, named after the northeastern Chinese city of Dalian, near where they were unearthed. They are shown to have a mixed ancestry from both Eurasian and American populations.
Dalianensis lived 17,000 years ago and were slightly bigger than existing wild horses.
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In the latest study, the scientists found that horses undertook multiple migrations across the Bering land bridge between 50,000 and 13,000 years ago, with genetic exchanges between North America and Eurasia in both directions.
Researchers in Britain, Canada, France, Russia and the United States published their findings in the peer-reviewed journal Science on Friday.
'We find that Late Pleistocene horses from Alaska and northern Yukon are related to populations from Eurasia and crossed the Bering land bridge multiple times during the last glacial interval,' the team wrote.
'We also find deeply divergent lineages north and south of the American ice sheets that genetically influenced populations across Beringia and into Eurasia.'
Horses evolved in the Americas around 4 million years ago. About 20,000 years ago, warming after the Last Glacial Maximum submerged the Bering land bridge, which led to a decline in horse populations in North America.
They largely disappeared from the region about 10,000 years ago but continued to evolve and were domesticated in Eurasia.
Spanish settlers likely reintroduced horses to the Americas in the 1500s. Horses were then moved through trade routes and became key to many Indigenous cultures across the American Southwest and the Great Plains.
Lead author Ludovic Orlando, director of the Centre for Anthropobiology and Genomics in France, said while some lineages native from America migrated and brought their genes far into Eurasia, a Eurasian lineage expanded from the Ural Mountains into western Alaska and all across the Arctic.
This region comprises present-day northern Russia, Siberia and Alaska.
'The lineage that migrated the other way around from America into Eurasia indeed reached out to China, since we find subfossils in the Sukhkaya cave in the Russian Far East, not far from the Chinese city of Dalian and next to the Jilin Province, carrying a fraction of American genetic ancestry,' he said.
'These subfossils are older than 50 thousand years ago, and related to Equus dalianensis from around Dalian.'
He said Dalianensis horses could be seen as 'a mixture of populations originating both from Eurasia and America'.
'It implies that a Eurasian lineage first established and evolved in the region, and at some point mixed with another lineage that expanded in the region, and originated all the way up to America,' Orlando added.
When asked about the motivations for horses to migrate vast distances across continents in both directions, he pointed to a Native American Lakota concept for the rationale for life forms to move.
Orlando said when environmental conditions became suboptimal for horses and their associated microbes and food sources, 'they would reach out to other more favourable environments where they can thrive again, and maybe merge with other populations that would reinforce them'.
'Migration is thus one of the key ways that life has to develop,' he said. 'Maintaining populations as they are and within limited habitats may not be enough as they could not [necessarily] thrive, mix and develop new alliances to face fast-changing environments.'
First author Yvette Running Horse Collin, a postdoctoral researcher in the archaeology, genomics, evolution and societies group of the laboratory in France, said horses 'moved great distances regularly until relatively recent times when their natural patterns were interrupted'.
'For the Lakota, and many Indigenous Peoples, our relationship and science around the horse helps us to understand that the horse was designed to move,' she said. 'The horse is not only responding to change, it is also actually part of the change.'
To conserve horses, Collin said it was important to protect other forms of life that move with horses.
'It is for this reason that one of the research outcomes of this study is to suggest the creation of corridors that would allow life to move – together – as needed,' she said.
'One of our next steps will be to apply the findings in this study to preserve life in our traditional territory in the Black Hills of South Dakota and provide for the scientific measurement of those efforts.'
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