KZN team finds ‘oldest evidence’ of arrow poison use by humans on 60,000-year-old arrowheads

Scientists have discovered what they say are the oldest traces of arrow poison that had survived on 60,000-year-old arrowheads.

The quartz arrowheads were excavated at the Umhlatuzana Rock Shelter in KwaZulu-Natal, about 30km from Durban, and the discovery suggests that hunter-gatherers then had a sophisticated understanding of toxic substances and were using them to bring down game.

The researchers from Sweden and the University of Johannesburg identified the millennia-old poison as having come from the gifbol plant (Boophone disticha), which, with its fan of long, green, strap-shaped leaves, has a deadly reputation. It is known to kill livestock and is still used by some hunter-gatherers to poison their arrows.

Identifying the poison from microscopic traces proved not only challenging, but was also the culmination of a 20-year journey for one of the scientists.

Professor Marlize Lombard, a researcher at the Palaeo-Research Institute at the University of Johannesburg, first saw the Umhlatuzana Rock Shelter quartz arrowheads when she was completing her Phd. She noticed that some of them appeared to have some sort of residue on them.

“I started use-trace analysis of the small quartz artefacts during my PhD. It revealed that they were probably used as arrow tips or barbs, and I could see preservation of adhesives under the microscope. But at the time, I couldn’t say it was poison, because I couldn’t verify it chemically,” she recalls.

The findings of the study were published in the scientific journal Science Advances.

“Since then, I’ve been looking for a person and a laboratory to work with. And 20 years later I found an archaeochemist. And we decided to collaborate.”

That archaeochemist was Professor Sven Isaksson from the Archaeological Research Laboratory at Stockholm University, an expert in the analysis of organic residues in archaeological materials.

More than 200 arrowheads have been excavated from the site, but the team selected those artefacts with signs of residue on them.

“We extracted residues from 10 arrowheads, and we found the same molecules on five out of the 10. That’s extraordinary,” Lombard says.

The analysis found the presence of two alkaloids, buphanidrine and epibuphanisine, both of which are found in the gifbol plant.

Further study of 250-year-old arrowheads held in Swedish collections, which had been collected by travellers during the 18th century, also revealed traces of the same poison.

“Finding traces of the same poison on both prehistoric and historical arrowheads was crucial,” Isaksson says in a statement. “By carefully studying the chemical structure of the substances and thus drawing conclusions about their properties, we were able to determine that these particular substances are stable enough to survive this long in the ground.”

Lombard, who has been studying hunting groups across Africa, believes these 60,000-year-old hunter gathers would have used these arrows similarly to how modern-day San use them today.

One difference is that the San in more recent times have derived their arrow poison from the larva of the Diamphidia beetle.

Both the San and our 60,000-year-old ancestors would have stalked their prey and when close enough fired the poisoned arrow. The poison is slow-working and would have required the hunters to track the animal for hours or even days before it finally succumbed.

“It is a neurotoxin that goes into the blood and it affects your heartbeat; you will become drowsy and disoriented. It will be easier to track the animal,” Lombard explains.

The ability to find and select a poison, then apply it to an arrow shows rather modern problem solving, believes another member of the

Team, Professor Anders Högberg of the Department of Cultural Sciences at Sweden’s Linnaeus University.

“Using arrow poison requires planning, patience and an understanding of cause and effect. It is a clear sign of advanced thinking in early humans,” he says in a statement.

“This tells us a lot about cognition, and it is the oldest evidence for the most complex technology known in hunter gatherer behaviour,” Lombard adds.

She suspects that this advanced behaviour has its roots in recent evolution, when human brain shape changed about 100,000 years ago.

“So, around about 100,000 years ago our brain shape changed. We have this globular brain that we have today. I therefore think that from about 100,000 years ago, people in southern Africa could think and problem-solve in similar ways we do today,” she explains.

Now that the team have found what they believe is the oldest use of poisoned arrows, the search is on for more evidence.

“We need to now look at sites of a similar age or younger to see if this is really a continuous tradition. This is very difficult work that will take years. But I think that over the next decade or so we and other researchers will find more evidence of similar behaviour,” Lombard says. DM