Close-up of a rib bone from a stag that has a fragment of stone tool (centre) embedded in it. It is believed that the tool belonged to Neanderthals. The bone was found in the Galeria de las Estatuas section of the Cueva Mayor cave system in the Sierra de Atapuerca foothills in northern Spain. The Cueva Mayor site was first discovered in 1910 and is believed to contain evidence of the final phase of human evolution, between 127,000 and 11,000 years ago.