WASHINGTON, March 5 (Xinhua) -- An international team of archaeologists has uncovered the earliest known evidence of horses being domesticated by humans.

    The discovery, which suggests that horses were both ridden and milked, could point to the very beginnings of horse domestication and the origins of the equine breeds we know today.

    Led by the Universities of Exeter and Bristol in the United Kingdom, the research will be published Friday in leading academic journal Science.

    The researchers have traced the origins of horse domestication back to the Botai Culture of Kazakhstan about 5,500 years ago. That is about 1,000 years earlier than previously thought and about 2,000 years earlier than domestic horses are known to have been in Europe.

    The findings strongly suggest that horses were originally domesticated, not just for riding, but also to provide food, including milk.

    Through extensive archaeological fieldwork and subsequent analysis, using new techniques, the team developed three independent lines of evidence for early horse domestication.

    Their findings show that in the fourth millennium BC horses in Kazakhstan were being selectively bred for domestic use. They also show that horses were being harnessed, possibly for riding, and that people were consuming horse milk.

    Analysis of ancient bone remains indicated that the horses were similar in shape to Bronze Age domestic horses and different from wild horses in the same region. This suggests that people were selecting wild horses for their physical attributes, which were then amplified through breeding.

    The team used a new technique to search for "bit damage" caused by horses being harnessed or bridled. The results showed that horses had indeed been harnessed, suggesting they could have been ridden.

    Using a novel method of lipid residue analysis, the researchers also analyzed Botai pottery and found traces of fats from horse milk. Mare's milk is still consumed in Kazakhstan, a country in which horse traditions run deep, and is usually fermented into a slightly alcoholic drink called "koumiss." While it was known that koumiss has been produced for centuries, the study shows the practice dates back to the very earliest horse herders.

    Lead author Alan Outram of the University of Exeter said: "The domestication of horses is known to have had immense social and economic significance, advancing communications, transport, food production and warfare. Our findings indicate that horses were being domesticated about 1,000 years earlier than previously thought. This is significant because it changes our understanding of how these early societies developed."

    The steppe zones, east of the Ural Mountains in Northern Kazakhstan, are known to have been a prime habitat for wild horses thousands of years ago.

    Horses were a commonly-hunted animal. This may have set the stage for horse domestication by providing indigenous cultures with access to plentiful wild herds and the opportunity to gain an intimate knowledge of equine behavior.

    Horses appear to have been domesticated in preference to adopting a herding economy based upon domestic cattle, sheep and goats. Horses have the advantage of being able to adapt to severe winters and are able to graze year round, even through snow.

    Cattle, sheep and goats need to be provided with winter fodder, and were a later addition to the prehistoric economies of the region.