Researchers have found traces of what appears to be plant-derived poison on tiny stone arrowheads from South Africa dated to 60,000 years ago. The finding pushes back the origin of this revolutionary hunting technology by tens of thousands of years.
Scientists have long been fascinated by the development of poisoned hunting weapons. For one thing, they would have seriously leveled up our ancestors’ foraging game. For another, they offer a window into cognition: poisoned weapons represent a highly sophisticated technology that requires knowledge of how to extract poison from plants, how poison affects prey and how to exploit those effects to increase hunting efficiency.
Previously the oldest direct evidence of poisoned weapons came from bone arrowheads in an Egyptian tomb dated to little more than 4,000 years ago and bone arrowheads from Kruger Cave in South Africa dating to around 6,800 years ago. Researchers had reason to suspect the technology might be significantly older than that, however, because they had found much older bone and stone arrowheads that closely resemble the poisoned ones in their size, shape and wear patterns. But scientists didn’t have direct evidence of poison on these older weapons.
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In a paper published today in Science Advances, Sven Isaksson of Stockholm University and his colleagues report on their microchemical and biomolecular analyses of residues found on 60,000-year-old quartz arrow tips from Umhlatuzana Rock Shelter in KwaZulu-Natal, South Africa. Their analyses revealed toxic compounds from members of the Amaryllidaceae family of flowering plants that are indigenous to southern Africa. The authors surmise that the ancient humans who made these arrowheads used secretions from the bulbs of Boophone disticha, an Amaryllidaceae species that is well known to have been used for centuries as an arrow poison .
Isaksson and his colleagues observe that these poisoned arrows probably did not kill prey animals instantly, if more recent examples of poisoned arrows are any indication. Instead they would have weakened the animals over time. Hunters would have needed to track the wounded animals as they ran.
“Poison is a breakthrough adaptation for humans, and here we see it appear by at least [60,000 years ago],” says Curtis Marean of Arizona State University, who was not involved in the new study. He notes that the fact that the poison was found on microliths—tiny stone tools—is also important. Miniaturization of stone tools was another key advance for humans, one that helped lead to bow and arrow technology, for instance. According to Marean the new finding raises the question of whether the development of microlith technology is related to the development of poison. “I think that seems likely,” he says.
