Capuchin Monkeys and the 3,300-Year-Old Tool Tradition

In Brazil’s Serra da Capivara National Park, a capuchin monkey was caught on camera smashing a palm nut with a rock, just inches from a cluster of stone tools dating to 1,200 BCE. Among the scattered relics, archaeologists found stone hammers pitted with wear marks and anvils ringed by the broken shells of cashew nuts-clearly not the work of humans. Some hammers weighed nearly two pounds, far heavier than anything the capuchins themselves. But what really shattered expectations was the discovery of layered tool sites: distinct patches where, every few years, generations of capuchins returned to the same limestone slabs. Each new layer of tools showed a gradual improvement-older stones rough, newer ones carefully chosen for their shape and heft. At least four generations, and probably more, had used these exact spots long before written history, leaving behind a fossilized map of their learning. No other non-human primate outside Africa has left a tool tradition this old. And the nut that monkey opened was a jatobá, with a shell tough enough to crack human teeth-unless you know the secret passed down by capuchins for thirty-three centuries: the perfect swing of a stone more ancient than most civilizations.