Stone points hint at 125,000-year-old poison use in Arabia

What makes the poison interpretation plausible?

Several points carried chemical residues linked to the arrow poison tree, Acokanthera schimperi, a toxic plant native to eastern and central Africa and southern Arabia. African hunters have historically coated spear tips and arrowheads with its extracts to paralyze or kill game.

The combination of impact damage, animal tissue and toxin-linked chemistry supports a poisoning interpretation, but it does not establish one. If the points were made when the lake was 125,000 years old, they would be substantially older than poisoned arrowheads recently identified in South Africa, which date to around 60,000 years ago.

Clarkson cautioned: “We haven’t demonstrated exactly how the poison was prepared or whether it was effective. So I’d describe these as potentially the oldest evidence for poisoned hunting weapons, rather than an unequivocally established first.”

A poison’s effect depends on the substance, dose and route into the body. Material entering a wound need not behave as it would when swallowed. Historical hunters sometimes removed meat around a poisoned wound before eating the rest of an animal. The site cannot show whether people here used that method or avoided self-poisoning another way.

How complex was the tool technology?

The preserved organic materials complicate a familiar picture of early toolmaking. Clarkson said researchers often underestimate technological complexity because organic components decay. People here apparently combined stone with wood, fibers, resins and possibly toxins to make multi-part tools and weapons, rather than merely knocking flakes from larger stones.

Eleanor Scerri, an archaeologist at the Max Planck Institute of Geoanthropology who did not join the research, called the evidence remarkable. She linked microscopic traces of spear-tip hafting (attachment to wooden shafts) to the site-wide relationship between hunting tools and hippo bones.

Jeffrey Rose, a Paleolithic archaeologist at the University of Algarve in Portugal who also did not participate, noted that Arabian sites with both tools and animal bones are rare. Some flakes at Uruq Aljelibah fit back together, indicating onsite toolmaking, he said, and he called the assemblage valuable new data.

Who made the tools?

The researchers found no human remains. They suspect the site most likely belonged to modern humans (Homo sapiens), because the species had already expanded from Africa into Southwest Asia by this period. The identity of the toolmakers remains unconfirmed.

The Arabian Peninsula sits between Africa and Asia and served as a major corridor for human dispersal. Wetter intervals could make its hostile landscapes habitable. The findings strengthen the view that such periods created migration corridors and productive habitats capable of sustaining repeated occupation.

Clarkson said the people did more than pass through; they exploited these environments with sophisticated technologies and resources. Hippos and enormous buffalo around a lake in today’s Empty Quarter also underscore how dramatically regional landscapes and the global climate have changed.

How old are the artifacts, really?

Rose said: “Not one was excavated from the layers that were dated. The 125,000-year date belongs to the lake, not to the tools. For the tools, it is only a maximum age.”

The distinction matters because wind has stripped most Arabian sites of stratified deposits (layers formed in sequence), leaving artifacts in surface scatters (loosely exposed on the ground). Desert conditions make excavation difficult. The tools could therefore be younger than 125,000 years. Rose said researchers should seek artifacts sealed in lake beds, a difficult goal in Arabia.

What will researchers do next?

Clarkson wants to return for more animal fossils and, if possible, human fossils. He also plans chemical analyses and tests of tool function to identify plant compounds, determine their preparation and assess whether people deliberately applied them to hunting weapons. The team plans to search lake margins for other activity areas and better-preserved, stratified deposits.

The assemblage offers an unusually broad view of a vanished technological system combining stone, wood, fibers, resins and possible toxins. The next excavation will test whether the lakeshore records a 125,000-year-old hunting system or a later toolkit resting on an older landscape.