New study pushes back earliest use of poisoned weapons by 50,000 years

A new analysis of ancient arrowheads discovered in South Africa suggests that prehistoric humans began using poisoned weapons more than 50,000 years earlier than previously believed.

Researchers have identified traces of plant-based poison on five quartz arrowheads dating back around 60,000 years. The poison was derived from a bulbous flowering plant known as gifbol, or “poisonous onion,” which remained in use by traditional hunters in southern Africa until recent centuries, according to an article by Science News.

The findings were published earlier this week in the journal Science Advances and significantly revise earlier assumptions, as the oldest known poisoned arrowheads had previously been dated to less than 7,000 years ago.

“This is the earliest direct evidence of the use of poison and these are earliest poisoned arrowheads,” says Sven Isaksson, an archaeological scientist at Stockholm University and one of the study’s authors.

Isaksson and his colleagues analyzed arrowheads that were originally excavated in 1990 by South African archaeologist Jonathan Kaplan at the Umhlatuzana rock shelter, located in present-day KwaZulu-Natal province in southeastern South Africa.

To establish their age, the team first conducted geochemical and magnetic analyses to confirm earlier dating of the sediment layer in which the arrowheads were found. They then applied gas chromatography-mass spectrometry, a highly sensitive technique used to identify chemical compounds, to search for traces of poison residues on the artefacts. This analysis was guided by comparisons with poison residues found on 18th-century poisoned arrows collected in southern Africa by Swedish naturalist Carl Peter Thunberg.

The researchers detected traces of the same gifbol-based poison on both the prehistoric arrowheads and the much later historic examples, despite the tens of thousands of years separating them. According to Isaksson, the chemical match strongly suggests a shared tradition or repeated rediscovery of the same toxic plant.

It remains unclear whether knowledge of gifbol poison was passed down continuously over millennia or whether it was independently identified and exploited by different groups at different times, Isaksson notes.

The study also sheds light on the cognitive and behavioral complexity of early hunter-gatherers. Poison derived from gifbol is not instantly lethal, meaning that hunters would have needed to anticipate a delayed effect and track wounded animals over time until the toxin incapacitated them. This implies a sophisticated understanding of hunting strategies and animal behavior.

Although these early humans would not have understood the precise biochemical mechanisms behind the poison, the researchers argue that its use still required advanced mental skills. “Our study demonstrates that they had a knowledge system or procedural knowledge, enabling them to identify, extract and apply toxic plant exudates effectively,” the authors write. “Because poison is not a physical force, but functions chemically, the hunters must also have relied on advanced planning, abstraction and causal reasoning.”

The findings push back the timeline for complex weapon technologies and chemical knowledge in human prehistory, offering new insight into the ingenuity and adaptability of early Homo sapiens.

By Nazrin Sadigova