RESUMO
The Orce skull fragment from southern Spain, dated at 1.6 Myr, has been a subject of heated controversy since it was first discovered in 1982. If it is hominid, as its discoverers contend, it is by far the oldest fossil hominid yet found in western Europe and implies that human populations settled this region much earlier than was previously realized. Numerous stone artifacts found at the Orce sites provide evidence that hominids were indeed present there in the Lower Pleistocene. Some paleontologists maintain that the 8 cm diameter occipital fragment is from a horse, not a hominid. Two independent investigations of the residual proteins in the skull were undertaken, one at the University of Granada in Spain, the other at the University of California, San Francisco. Two immunological methods of comparable sensitivity were employed for detection and species attribution of protein extracted from fossil bone: the Granada team used an enzyme-linked-immunosorbent assay (ELISA), and the UCSF team used a radioimmunoassay (RIA). Both teams obtained reactions characteristic of human albumin in the Orce skull and horse albumin in some of the horse fossils. These results support the lithic evidence that hominids were living in Andalusia 1.6 million years ago.