Archaeologists excavating a South African cave have recovered remains of the oldest known complex projectile weapons. The tiny stone blades, which were probably affixed to wood shafts for use as arrows, date to 71,000 years ago and represent a sophisticated technological tradition that endured for thousands of years. The discovery bears on an abiding question about when and how modern human cognition emerged.

Fossils show that humans who basically looked like us had evolved by 200,000 years ago. Yet based on the cultural stuff they left behind, it looked as though anatomically modern humans did not begin reliably thinking like us until little more than 40,000 years ago. The new finds, which come from a site called Pinnacle Point 5-6 (PP5-6), indicate otherwise.

Kyle S. Brown of the University of Cape Town and his colleagues argue that the tiny points they found, which the ancient people at PP5-6 made by carefully heating and shaping stone, are a proxy for complex cognition and that the 11,000-year duration of the tradition indicates it was transmitted verbally from generation to generation.

The findings, published online November 7, 2012, by Nature, add to mounting evidence that modern cognitive capacity evolved at the same time as modern anatomy, with various elements of modern behavior emerging gradually over the subsequent millennia. (Scientific American is part of Nature Publishing Group.) A competing hypothesis holds that modern human behavior arose far more recently as the result of a fortuitous genetic mutation.

Brown and his collaborators conclude their paper by noting that this projectile technology, which allows one to attack from a safe distance, would have given modern humans a significant edge during hunting and interpersonal conflict as they spread out of Africa into Europe and encountered the resident Neandertals equipped with handheld spears.