New rock art sites have been found in Wadi Abu Dom, a valley in northern Sudan. The problem is that no one seems to know what they mean! The carvings go back as far as 3,000 BCE and are spread across 15 sites, drawn in the rock faces of the 'khors', which are the streams which feed into the main valley.
     The oldest shapes found are of spiral motifs, similar to other artwork found in the Sahara Desert. The lead researcher at the sites is Tim Karberg, of the Westfalische Wilhelms-Universitat Munster, in Germany. When asked what he thought the spirals represented, he dismissed theories that linked them to astronomy or astrological signs and believes that are linked to mathematics. He is quoted as saying "The regularity of the spiral might be one of the earliest mathematical ideas the people developed".
     Other images appear to depict armed riders, horned animals and even crosses. Despite talking to the local inhabitants (who offered the 'useful' advice that the images were older than their grandfathers!) the team is no closer to discovering the reasons for the designs than when they started.

Edited from Live Science, UPI (13 May 2011)