Are wheel-like objects first discovered in the Arabian Desert decades ago among the oldest man-made objects on Earth?
Archeologists have used a technique called optically stimulated luminescence to date thousands of stone structures – some following a shape similar to a kite, while others look like a bicycle wheels with spokes – in the Wadi Wisad region of Jordan.
The study was published in October in the Journal of Archeological Science and Arabian Archaeology and Epigraphy, and noted that the wheels were arranged in clusters and that their spokes followed a southeast to northwest direction, along the path of the sun's rise during the winter solstice.
The stone objects appear to have been constructed about 8,500 years (which means that they would be considered prehistoric), with evidence suggesting one object was altered several thousand years later, researchers found.
Evidence of charcoal from trees and shrubs discovered on the sites and dating back more than 6,000 years ago also shows that the area, now a dry desert, may have once offered more hospitable living conditions.
Researchers have compared the structures to the Nazca Lines of Peru, where more than 1,000 geometric objects can be found, dating back about 1,300 to 2,000 years.
The outside world first got wind of the objects in Jordan in 1927, when a member of Britain’s Royal Air Force published an article called “The Works of Old Men.”
Gary Rollefson, a professor at Whitman College in Walla Walla, Wash., told Live Science that two wheels recorded in the study did not follow strict geometric criteria.
"They contrast sharply with some other wheels that appear to have been set out with almost as much attention to detail as the Nazca Lines,” he said, indicating that the wheels may have been used constructed for separate purposes like tombs for burials.
Rollefson, a director of the Eastern Badia Archaeological Project, said the settlements were abandoned in 6,900 BC as people migrated to the country’s highlands.
In a lecture called “A Kinder, Greener Black Desert: Results of Archaeological Research of Neolithic Sites,” Rollefson said about 3,000 people made up herding and hunting communities until adverse environmental conditions like drought drove about 90 percent of them out.
“The new residents in the area, who herded sheep and goats, used to hunt gazelles,” Rollefson said. “We found large quantities of wild and domesticated animal bones in addition to hundreds of arrowheads and butchering tools."
Another research team, the Aerial Photographic Archive for Archaeology in the Middle East project, has been studying the structures in Jordan since 1997, capturing 91,000 images and maps.
Those studies have recently recorded smaller wheel-like structures in Saudi Arabia and Yemen by using Google Earth images. The images show the spokes inside these wheels vary from those in Jordan, appearing more like triangles or kites. Another structure appears more akin to a bulls-eye than a wheel, according to David Kennedy, of the University of Western Australia.
Dr. Kennedy said the common perception in the scientific community is that the kite-like structures were used as traps to capture migratory animals. More than 900 such structures have been found so far, but the addition of high-resolution technology will likely divulge additional structures and variations.