Archaeologists find world’s oldest multi-component hunting poison in 7,000-year-old bone

Archaeologists in South Africa made a remarkable discovery on arrow blades lodged inside the femur of an antelope: the oldest mixed poison on record.

The femur bone belonged to an antelope that hunters targeted long ago with three deadly arrows. Researchers have had the bone since 1983, but they only recently decided to examine it more closely.

In a new paper, the rare and significant artifact from the painted rock shelter in Kruger Cave in South Africa possessed a much more exciting feature than just the ancient blades.

Researchers believe that the femur’s contents could be a combination of at least two toxic plant ingredients. There’s also evidence of a third toxin.

The “complex recipe,” as the study authors phrased it, provides a stunning portrait of how sophisticated medicine traditions were 7,000 years ago.

A poisonous mixture with three toxins

Originating from a hunt that occurred 7,000 years ago, the femur might have fallen into researchers’ hands in 1983, but it remained unexplored until 2022.

A recent excavation of Kruger Cave, a painted rock shelter and living heritage site in western Magaliesberg, South Africa, reopened the intriguing case.

X-rays in the past showed researchers that three bone arrowheads had punctured the bone, leaving traces behind in the marrow cavity, the first study author, Justin Bradfield, explains in Science Alert.

Advanced imaging techniques such as micro-CT enabled them to take thousands of X-rays to construct a 3D model of the femur. They had a hunch that they might detect toxic plant-based materials. After all, as the paper outlines, research understood that humans started using poisons 60-70,000 years ago.

Tests confirmed that the “sediment-like matrix filling the marrow cavity” comprised toxic plant residues with a lethal final touch, according to Bradfield.

The hunting poison revealed new details about a hunt

After performing a chemical analysis, researchers detected the presence of digitoxin and strophanthidin. These are two commonly known toxic cardiac glycosides that affect the heart muscle. The addition of ricinoleic acid might reflect the “oxidative breakdown of the toxin lectin ricin,” as per Science Alert.

Furthermore, these plant derivatives might have originated elsewhere as they weren’t native to the area surrounding Kruger Cave. Bradfield suspects they either traveled to gather their organic materials or acquired them through trade.

Though not the oldest poison on record, the antelope’s marrow cavity holds the first composite mixture ever found in history. Nonetheless, using poison in the hunt marks an early technological innovation. Human ancestors affirmatively employed complex poisons for hunting.

Bradfield and his colleagues emphasized the importance of their findings, noting, “To date, there have been several attempts to identify putative poisons on stone and bone arrowheads with varying degrees of confidence,” study authors state in the study.

The research published in Science Direct demonstrates that archaeobotany and organic chemistry as disciplines can enrich and enhance the picture of the past.