In March of 1994 some spelunkers exploring an extensive cave system in northern Spain poked their lights into a small side gallery and noticed two human mandibles jutting out of the sandy soil. The cave, called El Sidrón, lay in the midst of a remote upland forest of chestnut and oak trees in the province of Asturias, just south of the Bay of Biscay.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.
The bones from El Sidrón were not Republican soldiers, but the fossilized remains of a group of Neanderthals who lived, and perhaps died violently, approximately 43,000 years ago. The locale places them at one of the most important geographical intersections of prehistory, and the date puts them squarely at the center of one of the most enduring mysteries in all of human evolution.
So, while the new genetic evidence appears to confirm that Neanderthals were a separate species from us, it also suggests that they may have possessed human language and were successful over a far larger sweep of Eurasia than previously thought. Which brings us back to the same hauntingly persistent question that has shadowed them from the beginning: Why did they disappear?
When teeth are imaged at high resolution, they reveal a complex, three-dimensional hatch of daily and longer periodic growth lines, like tree rings, along with stress lines that encode key moments in an individual's life history. The trauma of birth etches a sharp neonatal stress line on the enamel; the time of weaning and episodes of nutritional deprivation or other environmental stresses similarly leave distinct marks on developing teeth. "Teeth preserve a continuous, permanent record of growth, from before birth until they finish growing at the end of adolescence," Smith explained
