The milk drinkers of the steppe
On the vast, open plains of northern Kazakhstan, the Botai culture flourished between 3700 and 3100 BCE. These people were not nomadic hunters in the way of their ancestors; they built large, permanent settlements with more than 160 semi-subterranean pit-houses. The most telling discovery from these sites, first excavated in 1980 by Viktor Zaibert, is the overwhelming abundance of horse bones, which constitute up to 99% of all animal remains. While this points to a diet heavy in horse meat, a more subtle clue found on their pottery shows something else.
Using a technique called lipid residue analysis, scientists examined the fats absorbed into the porous surfaces of ancient Botai pottery sherds. The chemical signature of these fats was unmistakable: it was mare's milk. This finding shows that the Botai people were hunting horses and were also managing them in herds, milking the mares, and likely fermenting the milk into a beverage similar to the modern Central Asian drink, koumiss. This pushes back the timeline for horse domestication by about 1,000 years, identifying the Botai as the earliest known horse pastoralists.
Evidence of horse management
The evidence for domestication at Botai extends beyond dairy. Archaeologists have identified patterns of postholes that suggest the construction of corrals or enclosures for managing horses. Soil analysis within these areas reveals high phosphate levels, consistent with the accumulation of large quantities of manure from penned animals.
Evidence also comes from the horses' teeth. Microscopic analysis of the lower second premolars on some horse skulls reveals a specific type of wear. This "bit wear" is a beveling caused by the friction of a mouthpiece, part of a bridle used for riding and controlling a horse. While some recent studies have questioned whether this wear is definitively from a bit, it is a strong indicator of early equestrianism. Genetic studies also show a higher frequency of the leopard-spotted coat color gene (TRPM1) in Botai horses, a trait that also causes night blindness and would have been a disadvantage in the wild, suggesting human selection.
Recent ancient DNA analysis has shown that the Botai horses are not the direct ancestors of modern domesticated horses (Equus caballus). Instead, they are the ancestors of Przewalski's horse, long thought to be the last truly wild horse. This suggests Przewalski's horses are actually feral descendants of the Botai's herds, meaning there are no truly wild horses left on Earth. Modern domestic horses seem to have descended from a separate domestication event, having only about 2.7% Botai-related ancestry.