Few visitors to Kiev's natural history museum notice the skull of a stallion in a quiet corner of the prehistoric animal hall. The woolly mammoth skeleton, standing 12 feet at the shoulder, is much more impressive.
But 6,000 years ago, that stallion may have been part of a development nearly as significant as the invention of the wheel. Some intrepid forebear of today's Ukrainians probably stuck an animal bone in its mouth, attached reins, climbed aboard the beast and invented horseback riding.
That is the controversial conclusion of American anthropologist David Anthony, who recently completed experiments that he says showed the skull belonged to the earliest known riding horse in the world.
"This was not a wild horse taken on a joy ride," Anthony said in a telephone interview from New York. "It was (ridden) regularly for months, maybe years."
If Anthony is right, the people who buried the stallion's head near the modern town of Dereivka, 150 miles south of Kiev, had mastered the seemingly simple but revolutionary technique of horseback riding in 4000 BC, about 2,000 years earlier than previously thought.
The name they called themselves is lost in the mute millennia before writing was invented. But archeologists call them the Seredniy Stih, after an island in the Dnieper River where their culture was first discovered.
Before Anthony's studies, theories that the Stih were the world's first horsemen had been percolating in Soviet scholarly circles since 1964, when Ukrainian archeologist Dmytro Telehin excavated a horde of horse bones--including the separately buried stallion's skull--in Dereivka. Radiocarbon and other testing dated Dereivka's artifacts to about 4000 BC.
"It was a sensation," said Yuri Rasamakin, a Ukrainian expert on the period.
Wild horses had been excavated all over the vast steppe between Hungary and Manchuria, where prehistoric people hunted them for food. Dereivka was unique if only because of evidence that the Stih were herding horses, not hunting them, making them the world's earliest known domesticated horses.
Telehin's conclusion was a controversial one, buried in Soviet academic literature behind the Iron Curtain. Few Western experts knew about it, fewer still accepted it.
Although many archeologists agree that horseback riding first arose somewhere on the steppe between the Dnieper and the Volga, the conventional wisdom, based on ancient drawings of horsemen, was that it began between 2000 and 1000 BC.
Even many of Telehin's Ukrainian colleagues disagreed with him, contending one horse bone is much like another.
"There is no direct method for distinguishing the bones of prehistoric wild horses from those of domesticated horses," argued Rasamakin, who is not convinced that the Dereivka horses were herded or ridden. "Telehin's theory about Dereivka was based on circumstantial evidence."
However, one of those circumstances caught Anthony's attention when he began studying Soviet archeological literature in the 1970s. Among the artifacts Telehin found near the Dereivka stallion were pieces of antler with holes bored through the center. He speculated they were cheek pieces--the parts of a bridle alongside a horse's mouth that connect the mouth bit to the reins. But he never tested his theory.
That is what Anthony, an anthropologist from Hartwick College in Oneonta, N.Y., set out to do. But instead of looking at horse bones, the American examined their teeth.
On the assumption that a bit will wear down the teeth, Anthony first compared the teeth of modern riding horses with wild horses such as Nevada mustangs. When he found that only the riding horses' teeth were worn, Anthony compared the Ukrainian find to the teeth of prehistoric horses excavated in Iran, France and the former Soviet Union. The Dereivka stallion was the only one with "bit wear," he said.
Although modern bits are made of hard metal, Anthony recently finished experiments showing that bits made of bone produce similar markings on the teeth.
"This is the first direct evidence of the use of bits," said Anthony, who said he plans to submit his findings for publication this month.
Since there is no purpose for a bit except to control a horse, he believes the bit wear proves that the Dereivka horse, whose skull reposes in the Kiev museum, is the world's earliest known mount. Judging by the wear on another horse from Dereivka, it was not the only one.
"This is disputable only if the (horse's) age is wrong," Anthony said. The Dereivka stallion's 4000 BC birth date is based on tests performed on other objects from the site. The skull itself has never undergone radiocarbon dating to prove its age.
After studying Telehin's research and interviewing the aging archeologist himself, Anthony says he is "convinced, at the moment," that the Dereivka skull is 6,000 years old.
He does face rival claims, however. Ukrainian archeologist Nadia Kotova recently excavated evidence of horse-herding cultures north of the Azov Sea that predate Dereivka by 1,500 years, leading her to believe that riding may have begun as early as 5500 BC.
"The only way to control a horse herd is on horseback," she said. "So, if those people were herding horses, they must have been riding them too."
Scientists may never know when the world's first equestrians emerged from the pedestrian prehistoric masses. Unlike bits, which marked a technological advance, the most basic riding equipment would have been reins tied to a horse's nose.
"That would leave no traces at all," Kotova said.
Whenever it began, Anthony compares the impact of horseback riding on prehistoric society to the revolution wrought by the private automobile in the United States.
"Riding was the first transition from leg power to another form of energy for moving things," Anthony said. It let people travel longer distances faster than ever before.
Nevertheless, if some people took decades to accept Ford's newfangled Model T despite its obvious advantages, then horseback riding--if it indeed began in 4000 BC--took 2,000 years to emerge on a mass scale in the sophisticated societies of the Mediterranean and Near East.
Some scholars speculate that riding had a lower-class aura because of its association with northern steppe "bumpkins." The fact that horses were not native to those warm climes, where they were called "foreign highland donkeys," may also have delayed their acceptance.