Horses evolved in North America and traveled across Beringia, where they further speciated and expanded their ranges. As far as we know, modern North American horses are descended from Eurasian lineages later brought by Europeans. Running Horse Collin et al. looked across modern and ancient samples and found that horse movement between North America and Asia was common across Beringia between 50,000 and 13,000 years ago. In the late Pleistocene, this route was lost, and connectivity between these populations ended, leading to the extinction of horses on their natal continent. Understanding how such losses of connectivity have affected species in the past should shape our efforts to maintain species into the future. —Sacha Vignieri

Climate affects habitat, food availability, and the movement and sustainability of all life. In this work, we apply Indigenous and Western scientific methods, including genomics and isotope profiling, on fossils from across Beringia to explore the effect of climate change on horses. 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. We also find deeply divergent lineages north and south of the American ice sheets that genetically influenced populations across Beringia and into Eurasia. As climate warmed and horses entered the ice-free corridor connecting Beringia and midcontinental America, restricted mobility and food availability impeded population growth. Our combined Western and Indigenous framework offers critical guidance for wildlife conservation amid ongoing climate change.