成人快手

The Inca civilisation that emerged from the highlands of what is now Peru and stretched over vast swathes of South America left many mysteries when it died out. One of them is the khipu - a knotted string device used as a way of communicating and recording events as there was no written language. Professor Sabine Hyland from St. Andrews University is on a mission to decipher what they mean. (Photo credit: Christine Lee.)