In a study published June 6 in the journal Nature, an international team of researchers analyzing 475 ancient horse genomes identified genetic changes that point to a domestication date of around 2,200 B.C. This is roughly 1,000 years later than recently suggested by another research team studying human skeletons from the semi-nomadic Yamnaya culture.

The study helps pinpoint the rise of horse-based mobility in human culture but also challenges the theory that large horse herds accompanied human migration across Europe thousands of years ago. Some experts hypothesize that while the Yamnaya and other early Western Steppe cultures might have started working with wild horses and using them for milk, those horses were not sufficiently domesticated for use in their mass migrations.

Evidence of husbandry

The horse genomes studied by these latest researchers were based in central Europe and the Carpathian and Transylvanian Basins (Eurasia’s Pontic-Caspian Steppe) until the end of the third millennium B.C.

The evidence of human management of these horses—meaning husbandry or domestication—includes a shorter time between generations (indicative of intentional breeding) and a sharp decrease in genetic diversity (indicative of some degree of selective breeding between certain individuals—”close kin,” according to the abstract).

The emergence 4,200 years ago of a new bloodline matching that of modern domesticated horses reportedly coincides “neatly” with the appearance of horse imagery and chariot burials in the archaeological record. According to several sources, a notable feature of this new type of horse—which spread rapidly across Europe and Asia—was a back shaped to facilitate riding by humans.

The militaristic Sintashta people were prominent horse breeders and traders in this region during this period. Indeed, the earliest known horse-drawn chariots have been unearthed in Sintashta burials. It is believed that this culture used horses to help expand its territory, driving the spread of this new bloodline, which quickly became dominant throughout Eurasia.

‘Domestication bottleneck’

According to the research abstract: “We find that reproductive control of the modern domestic lineage emerged ~2,200 BCE (Before Common Era) through close kin mating and shortened generation times. Reproductive control emerged following a severe domestication bottleneck starting no earlier than ~2,700 BCE and coincided with a sudden expansion across Eurasia that ultimately resulted in the replacement of nearly every local horse lineage.

“This expansion marked the rise of widespread horse-based mobility in human history, which refutes the commonly held narrative of large horse herds accompanying the massive migration of steppe peoples across Europe ~3,000 BCE and earlier.

“Finally, we detect significantly shortened generation times at Botai ~3,500 BCE, a settlement from Central Asia associated with corrals and a subsistence economy centered on horses.

“This supports local horse husbandry before the rise of modern domestic bloodlines.”

It is believed that the domestication of horses, once it started, was a process that occurred relatively quickly compared to the earlier domestication of dogs, sheep and cattle.