“Rather than looking at how we shaped the horse, I looked at how horses shaped us.”
Sandra Olsen, curator of anthropology
Harnessing the Horse
After more than a decade of sleuthing in the central Eurasian country of Kazakhstan, zooarchaeologist Sandra Olsen and her research team reveal the earliest traces of humans domesticating the horse some 5,500 years ago.
Sandra Olsen in front of a re-creation of her dig site, on view through July 5 as part of
The Horse exhibit. photo: Ric Evans
Sandra Olsen knows all too well that life isn’t easy on the arid, windy
plains of northern Kazakhstan, where she’s directed field expeditions since the early 1990s. Temperatures plummet to 50 below in the winter, and summer brings unbearable heat, grass fires, hail, locusts, spiders, and tornadoes. “Almost like the biblical plagues,” muses Olsen, curator of anthropology at Carnegie Museum of Natural History.
Even with modern amenities like cell phones and all-season tents, working in these extreme conditions is challenging at best. Perhaps that’s why the ancient Botai people—trying to eke out survival there in the fourth millennium B.C.—resolved to domesticate wild horses, slaughtering the stallions for meat and milking the mares.
“With domesticated horses, you work harder than if you are a nomadic hunter-gatherer, but you have a reliable meat supply,” says Olsen. “That stability always translates into population growth, which allows you to build and expand your society.”
Olsen and an international scientific team recently uncovered new evidence suggesting the Botai horse herders were, in fact, the earliest known people to make this important technological advance.
The researchers published their findings in March in the prestigious journal Science, setting the archaeological community abuzz with excitement about finally having a clearer picture of the dawn of the human-horse relationship.
“The horse was one of the most important animals ever domesticated,” says Olsen, pointing to the enduring role our equine friends have played in aspects of human achievement ranging from trade to transit, work to warfare. “If we would try to extract the horse from the course of human history, we would have no idea what we would be like.”
But the mystery of exactly when, where, and how humans began to control wild horses and direct their breeding has long puzzled Olsen and other archaeologists.
Studies have concentrated on the Eurasian steppes—stretching from Hungary to Mongolia—where wild horses roamed in abundance for centuries.
Scientists once believed the first domesticated horse lived in 4,000 B.C. in Ukraine after the discovery of a horse skull with teeth worn from champing at a metal bit in a pit at an ancient site. That finding was recently discredited when it was found to be a more recent, Iron Age animal. All the while, Olsen focused her efforts on the Botai settlement and its sister villages, where she has been digging since 1993.
Unlike most livestock, domesticated horses don’t differ much skeletally from their wild ancestors, making it difficult to find clues in ancient bones. That’s why Olsen decided to search for answers by recreating the lifestyle of the herders.
“If you have domestic herds, the people’s lives are changing, and that should show up in the archaeological record,” Olsen says. “Rather than looking at how we shaped the horse, I looked at how horses shaped us.”
Olsen uncovered many lines of secondary evidence suggesting domestication, including a horse corral; sacrificial burial pits; horse manure in roofing materials; heavy bones that would have been left behind at the kill site if the horses were hunted far away; and tools to make rawhide leather strips, possibly for bridles, lassoes, and hobbles.
The biggest site contains about 150 adobe pithouses that probably sheltered more than 1,000 permanent settlers. “Such a large population of hunters would have quickly exhausted the local herds of wild game and been forced to become nomadic again,” Olsen says.
While support for her theory continued to build over the past decade, Olsen still lacked direct evidence to make her case.
That came through the chemical study of Botai pottery shards, with the help of archaeologist Alan Outram and his colleagues at the Universities of Exeter and Bristol in the United Kingdom. They used a novel method of lipid analysis to detect traces of fats from horse milk on the clay pots. As Olsen says, “No one in their right mind would milk a wild mare.
“I hung in there for many years and just kept building the record,” she says. “Now we’ve actually got a product of the horses that can’t be obtained from wild animals, and everybody accepts that we have domesticated horses.”
“Sandi has been like Perry Mason in compiling really strong circumstantial evidence that has been controversial,” says Melinda Zeder, director of the Archaeobiology Program at the Smithsonian’s National Museum of Natural History. “With the mare’s milk, though, she finally found the smoking gun.”
Olsen’s recent Science paper reports these findings and also presents two more pieces of evidence of horse taming at Botai. Measurements of the lower leg bones of horses found at the site show they were more slender than their wild counterparts, a trait selected by breeders for speed. Her team also found bit markings on horse teeth indicating they had been harnessed with a bridle for work and possibly for riding.
Just as we will never find the first stone tool or the first traces of fire, no one will ever be certain that Botai was the world’s very first horse farm, Olsen acknowledges. “What I’m hoping is for the bigger picture—that my colleagues adopt the same suite of techniques I used in Kazakhstan and apply them to sites in western Russia and Ukraine, with the hope of finding even earlier evidence of domesticated horses.”
Botai itself could hold more secrets. Olsen plans to return this August to study how changes in the seasonal levels of oxygen and strontium isotopes in ancient horse teeth might shed light on the animal’s migration patterns.
“If I had known how hard it would be early on, I might never have started working in Kazakhstan,” says Olsen, laughing. “But it’s so important in science to keep grinding away until you get where you are headed. It’s been a long time coming, and I’m just grateful that we made it.”