Horses originated in America and reached Europe through China, fossil DNA reveals

Everyone knows the story: when Spanish conquistadors rode into the New World, Native Americans were stunned by a towering, four-legged creature they had never seen before. Horses, the theory goes, were a European import to the Americas.
But a new fossil DNA study indicates that horses actually originated in North America millions of years ago and only reached Europe thanks to an unexpected genetic middleman in China.
An extinct lineage called the Dalian horse, once dismissed as a local oddity in northeastern China, had a distinctive American ancestry and passed it on to ancient horse populations in Siberia, the researchers say.
That gene flow means the bloodlines that later gave rise to modern European horses picked up their American roots via this Chinese crossroads.
“Dalian horses likely served as one route through which North American-related genetic ancestry entered Northeast Eurasian horse populations,” the researchers wrote.
“[The] findings position the Dalian horse as a key lineage for elucidating late Pleistocene equid evolution in Northeast Asia and the dynamics of trans-Beringian genetic exchange.”
The team led by the State Key Laboratory of Geomicrobiology and Environmental Changes published their findings in the peer-reviewed journal Proceedings of the Royal Society B: Biological Sciences on May 27.
Equids originated in North America during the early Eocene. The genus Equus, which first appeared around 4 to 5 million years ago, is the only surviving lineage, encompassing all existing horses, asses and zebras.

According to fossil records and genomic data, Equus dispersed from North America into Eurasia via the Bering Land Bridge about 2.6 million years ago, and then underwent extensive evolutionary diversification.
A 2025 study found that ancient horses repeatedly migrated between North America and Eurasia, reaching today’s Russian Far East near China during the late Pleistocene era when sea levels dropped and a land bridge connected the two continents.
The Dalian horse was one of the fossils studied and was shown to have a mixed ancestry from both Eurasian and American populations.
In the most recent study, scientists analysed 20 Dalian horse samples from the late Pleistocene and recovered their complete mitochondrial genomes. These samples were mostly unearthed from Qinggang county in western Heilongjiang province and Harbin, the province’s capital in the northeast.
The mitochondrial genome refers to the genetic material found in mitochondria, which generates most chemical energy in cells.
The researchers identified a “distinctive component” of eastern Beringian, which pointed to “American ancestry in Dalian horses”. This signal was absent from other northeast Asian equids.
“In light of spatiotemporal overlap between Dalian and northeast Siberian horses and the documented gene flow between them, our findings suggest that Dalian horses likely served as a conduit for the introduction of Eastern Beringian ancestry into the northeast Siberian gene pool,” the researchers said.
The gene flow appeared to have continued until after 50,000 years ago – a time frame consistent with the existence of the Bering Land Bridge. The team suggested that such exchange across the land bridge connecting Asia and North America was “intermittent and geographically limited”.
The discovery also rewrites the geographic range of the species. First identified from fossils in the Gulongshan Cave in Dalian, the horse was thought to be confined to northeastern China during the late Pleistocene.
The study found that two equid fossils from Yakutia in the Russian Far East fell within the mitochondrial diversity range of the Dalian horse.
This suggests that “Dalian horses likely extended from northern China at least northwestward to southern Siberia and northeastward to Yakutia during the late Pleistocene”.
Despite its role as a genetic conduit, the Dalian horse ultimately vanished. The study found that its downfall was not due to a lack of genetic diversity, but its inability to adapt to a changing climate.
Stable isotope analysis revealed the Dalian horse was a “specialised” grazer. As the environment shifted roughly 40,000 years ago – becoming more humid as dry grasslands were replaced by peatlands and wetlands – its narrow diet left it unable to adapt.
For the Dalian horse, its large body size and “limited ecological plasticity” meant it could not survive the loss of its high-quality forage.
“Dalian horses’ specialised dietary niche constrained its ability to adapt to rapid late Pleistocene environmental change, ultimately contributing to its extinction,” the study said.
This extinction trajectory mirrors other vanished large herbivores of the era, such as North American horses and the giant camel. The latter vanished when grassland ecosystems shifted towards wetter, less productive habitats.