National Geographic : 1996 Jan
1 'r ' 1 b I:. Conditions at the Spanish Save site, called La Sima de los Huesos, are grueling. Oxygen S is in short supply. And rock and dirt removed from test pits must be carried up a 40 Sfoot shaft in backpacks. Orange areas indicate test pits A hole to nowhere Tumbling into a gruesome grave, the body of a young pre-Neandertal is cast into the darkness some 300,000 years ago in northern Spain. The shaft, deep inside a cave in the Sierra de Atapuerca, may once have been located near a cavern mouth and hominid living area, long since oblit erated by a landslide. Researchers have excavated hundreds of animal bones and the remains of more than 30 humans from test pits in a cham ber beneath the vertical well (be low). The human fossils are unique: Reaching back to the very origin of Neandertals, they hint at a transi tional stage from a more ancient ancestor, Homo erectus. "It was like finding the Holy Grail," says paleon tologist Juan-Luis Arsuaga (below right, in red). "I spent my youth dig ging here. During the rest of my life, I'll explore maybe a third of the cave." The richness of the site has scientists baffled. Some believe bod ies were disposed of in the shaft simply for housecleaning. Others suspect ritual or cite the possibility of a natural disaster.