Study reopens debate over when horses were first ridden

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A new Science Advances paper argues that the start of horse domestication can't be reduced to the rise of the now-dominant DOM2 lineage around 2200 to 2100 BCE. Instead, the authors say archaeology, ancient DNA, osteology, and residue evidence together support a longer, more complex story in which horses from multiple genetic backgrounds were being managed, milked, and likely ridden well before DOM2 became widespread. That challenges a recent genetics-first narrative shaped by earlier high-profile studies that traced all modern domestic horses to a Pontic-Caspian lineage that spread rapidly across Eurasia about 4,200 years ago. (phys.org)

Why it matters: For veterinary professionals, the paper is a reminder that horse domestication was a prolonged human-animal relationship, not a single switch flipped by a favorable gene set. That matters because modern equine genetics, behavior, conformation, and disease risk sit on top of a much deeper history of management, selection, and lost diversity. Earlier work linked DOM2 horses to selection near genes associated with back conformation and behavior, while other reviews have noted that later intensive breeding reduced diversity and increased genetic load, themes that still resonate in equine health and breeding discussions today. (frontiersin.org)

What to watch: Expect more debate over how to define “domestication” in horses, and more efforts to combine genomics with archaeological and skeletal evidence rather than treating DNA alone as the deciding marker. (phys.org)