Some of the world's first farmers may have sped around in two-wheeled carts pulled by camels and bulls, suggests a new analysis on tiny models of these carts that date to 6,000-5,000 years ago. The cart models, which may have been ritual objects or children's toys, were found at Altyndepe, a Chalcolithic and Bronze Age settlement in Western Central Asia near Ashgabat, Turkmenistan. Together with other finds, the cart models provide a history of how wheeled transportation first emerged in the area and later developed. "Horsepower" is a common term today, but the ancients had bull-power, followed by camel-power, researcher Lyubov Kircho explained to Discovery News. "I think that the carts pulled by bulls were mostly used in agriculture in the 4th millennium, when the climate was more humid," said Kircho, who is at the Institute for the History of Material Culture at the Russian Academy of Sciences. [...]