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An unusually rich trove of fossils has been found at two sites in northern Spain's Atapuerca mountains. One, known as Gran Dolina, has yielded 800,000-year-old hominids that Spanish researchers believe are a new species, perhaps the most recent common ancestor of modern humans and Neanderthals. Named Homo antecessor (Latin for explorer or pioneer), they had a primitive jaw and prominent brow ridges but a projecting face, sunken cheekbones and tooth development similar to that of modern humans.
Less than half a mile away, antecessor's co-discoverer, Juan Luis Arsuaga of the Universidad Complutense de Madrid, is excavating at Sima de los Huesos (Pit of Bones), deep inside a natural cave. So far, his team has found thousands of fossils from at least 33 hominids of all ages. About 300,000 years old, they appear to represent an early stage of Neanderthal evolution. Explains Eric Delson, a professor of anthropology at Lehman College in New York City: "For the first time, we have a good population from a single place and enough variation to show Neanderthal features being distilled and standardized."
What occurred some 200,000 years later, when Homo sapiens first met their Neanderthal cousins--the only other hominid species that hadn't dwindled into extinction--is a matter of much speculation, scientific and otherwise. Our species would end up the only one left standing, but whatever happened to the Neanderthals didn't happen quickly. Plentiful archaeological evidence proves that Homo sapiens and Homo neanderthalensis inhabited the same general turf in many parts of Europe and the Middle East for thousands of years. That doesn't prove, however, that they lived as peaceable neighbors. Populations were so sparse that run-ins probably would have been rare.
A romantic notion of how the Neanderthals disappeared has been around for decades: perhaps they were eliminated by interbreeding with us. Maybe we all carry a bit of Neanderthal in our DNA. Two years ago, molecular biologists tested that hypothesis by extracting some DNA from a Neanderthal fossil and comparing it with that of modern humans. Their conclusion: the differences are great enough to rule out significant interbreeding, even though such mating would have been biologically possible.
But a skeleton discovered in Portugal last December gives new life to the old idea. Co-discoverer Joao Zilhao, director of the Portuguese Institute of Archaeology, and consultant Erik Trinkaus of Washington University in St. Louis, Mo., claim that the 24,500-year-old remains of a four-year-old child show a mix of human and Neanderthal features. The boy could simply be the love child from a single prehistoric one-night stand--except that the last true Neanderthals had disappeared from the area at least 3,000 years earlier. Plenty of experts are unwilling to be swayed by romance, however--especially the American Museum's Ian Tattersall, who says flatly, "It's just a chunky modern kid. There's nothing special about it."