1. Departamento de Paleontologa, Instituto de Geologa Econmica, Facultad de Ciencias Geolgicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
2. Departamento de Ciencias Histricas y Geografa, Facultad de Humanidades y Educacin, Universidad de Burgos, 09071 Burgos, Spain
3. Museo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Cientficas, Jos Gutirrez Abascal 2, 28006 Madrid, Spain
4. Laboratori d'Arqueologia, Universitat Rovira i Virgili, Plaza Imperial Tarraco 1, 43005 Tarragona, Spain

Correspondence to: Juan-Luis Arsuaga¹ Correspondence and requests for materials should be addressed to J.-L.A. (e-mail: Email: azara@eucmax.sim.ucm.es).

Abstract

The Middle Pleistocene site of Sima de los Huesos in Sierra de Atapuerca, Spain, has yielded around 2,500 fossils from at least 33different hominid individuals¹. These have been dated at more than 200,000 years ago^{2, 3, 4} and have been classified as ancestors of Neanderthals⁵,⁶. An almost complete human male pelvis (labelled Pelvis 1) has been found, which we associate with two fragmentary femora. Pelvis 1 is robust and very broad with a very long superior pubic ramus, marked iliac flare, and a long femoral neck. This pattern is probably the primitive condition from which modern humans departed. A modern human newborn would pass through the birth canal of Pelvis 1 and this would be even larger in a female individual. We estimate the body mass of this individual at 95 kg or more. Using the cranial capacities of three specimens from Sima de los Huesos, the encephalization quotients are substantially smaller than in Neanderthals and modern humans.