In addition to the fractures, cut marks left on the bones by stone tools clearly indicate that the individuals were cannibalized. Whoever ate their flesh, and for whatever reason—starvation? ritual?—the subsequent fate of their remains bestowed upon them a distinct and marvelous kind of immortality. Shortly after the nine individuals died—possibly within days—the ground below them suddenly collapsed, leaving little time for hyenas and other scavengers to scatter the remains. A slurry of bones, sediment, and rocks tumbled 60 feet into a hollow limestone chamber below, much as mud fills the inside walls of a house during a flood.
There, buffered by sand and clay, preserved by the cave's constant temperature, and sequestered in their jewel cases of mineralized bone, a few precious molecules of the Neanderthals' genetic code survived, awaiting a time in the distant future when they could be plucked out, pieced together, and examined for clues to how these people lived, and why they vanished.
The first clue that our kind of human was not the first to inhabit Europe turned up a century and a half ago, about eight miles east of Düsseldorf, Germany. In August 1856 laborers quarrying limestone from a cave in the Neander Valley dug out a beetle-browed skullcap and some thick limb bones. Right from the start, the Neanderthals were saddled with an enduring cultural stereotype as dim-witted, brutish cavemen. The size and shape of the fossils does suggest a short, stout fireplug of a physique (males averaged about five feet, five inches tall and about 185 pounds), with massive muscles and a flaring rib cage presumably encasing capacious lungs. Steven E. Churchill, a paleoanthropologist at Duke University, has calculated that to support his body mass in a cold climate, a typical Neanderthal male would have needed up to 5,000 calories daily, or approaching what a bicyclist burns each day in the Tour de France. Yet behind its bulging browridges, a Neanderthal's low-domed skull housed a brain with a volume slightly larger on average than our own today. And while their tools and weapons were more primitive than those of the modern humans who supplanted them in Europe, they were no less sophisticated than the implements made by their modern human contemporaries living in Africa and the Middle East.
One of the longest and most heated controversies in human evolution rages around the genetic relationship between Neanderthals and their European successors. Did the modern humans sweeping out of Africa beginning some 60,000 years ago completely replace the Neanderthals, or did they interbreed with them? In 1997 the latter hypothesis was dealt a powerful blow by geneticist Svante Pääbo—then at the University of Munich—who used an arm bone from the original Neanderthal man to deliver it. Pääbo and his colleagues were able to extract a tiny 378-letter snippet of mitochondrial DNA (a kind of short genetic appendix to the main text in each cell) from the 40,000-year-old specimen. When they read out the letters of the code, they found that the specimen's DNA differed from living humans to a degree suggesting that the Neanderthal and modern human lineages had begun to diverge long before the modern human migration out of Africa. Thus the two represent separate geographic and evolutionary branches splitting from a common ancestor. "North of the Mediterranean, this lineage became Neanderthals," said Chris Stringer, research leader on human origins at the Natural History Museum in London, "and south of the Mediterranean, it became us." If there was any interbreeding when they encountered each other later, it was too rare to leave a trace of Neanderthal mitochondrial DNA in the cells of living people.