An injury sustained by a Neandertal who died 50,000 years ago has puzzled scientists for nearly half a century. The individual, found at the site of Shanidar in Iraq and known as Shanidar 3, has a deep slice in one of the ribs, indicating that he was stabbed with a stone implement. The question has been: by whom? There are several possibilities: Either a fellow Neandertal or an early modern human did it intentionally, or the hapless victim himself or a hunting partner inflicted the wound by accident.

Researchers now think they have the answer. In a paper released online last week by the Journal of Human Evolution, Neandertal expert Steven Churchill of Duke University and his colleagues describe experiments in which they took replicas of stone points made by Neandertals and early moderns who lived in western Asia and wielded them against pig carcasses, which stood in for Neandertals. The investigators attached the points to wooden shafts and launched them with a calibrated crossbow that enabled them to deliver both high and low kinetic energy stabs to the carcasses' ribs.

Churchill and his colleagues found that the marks left on the ribs by the low-energy stabs, which were intended to simulate the blows delivered by the projectile weapons early modern humans' used, more often resembled the puncture evident on Shanidar 3's rib than did the marks that resulted from the high-energy stabs, which simulated the blows delivered by the handheld spears Neandertals brandished.

The team thus concluded that the culprit in the Shanidar 3 case was most likely a modern human. But other experts are not so sure. Paleoanthropologist John Hawks of the University of Wisconsin–Madison wrote in his blog that the findings are not sufficient to exclude the possibility that a Neandertal-made weapon created the wound.

But even if a modern human did fire a dart at Shanidar 3, that does not mean moderns drove the Neandertals to extinction in this way, as Churchill stressed in a statement. Although scholars once thought that modern humans might have killed off the Neandertals, studies conducted over the past decade suggest that climate or subtle differences in behavior or biology between the two human groups are to blame.

For more on the demise of the Neandertals, see the "The Mysterious Downfall of the Neandertals" in the August issue of Scientific American.