The Arabian Peninsula served as a crucial migration route for the first humans who ventured beyond Africa. Yet its unforgiving desert climate presented a formidable challenge to anyone attempting this ancient journey.

New research suggests that early humans met that challenge with complex survival strategies, possibly including composite hunting weapons coated with lethal plant poison. The evidence comes from a prehistoric campsite beside an ancient lake in southern Saudi Arabia.

Paleoclimate data indicates that Arabia was not always as dry as it is now. During the past several hundred thousand years, the peninsula repeatedly shifted between periods of greater humidity and intense aridity.

Even when rainfall increased, water remained unevenly distributed across the landscape. It collected in particular places that humans could use as stepping stones while moving out of Africa and into the rest of Eurasia.

One of those places was the ancient lake of Mundafan, which occasionally filled when the climate grew wetter. Along its former shore, archaeologists identified a 125,000 year old campsite called ‘Uruq Aljelibah.

Hunter gatherers living at the site preyed upon large herbivores that depended on the lake for survival. Excavations produced 5,511 stone artifacts, including several with impact fractures suggesting that they had been used as hunting weapons.

Researchers could not determine whether the stone points had been attached to thrusting spears or used as projectiles. However, adhesive residues and plant fibers found on their surfaces confirmed that the points were hafted and belonged to composite hunting systems.

“One of the most significant discoveries is evidence that some stone points were used as hafted hunting weapons,” said study author Chris Clarkson in a statement.

“This suggests people were manufacturing composite weapons made from multiple materials rather than simply using handheld stone tools.”

Residues appeared on 84% of the stone points examined, while 49% showed evidence consistent with hafting. The plant resins identified on the artifacts included Egyptian balsam, Indian senna, and some Pistacia species.

The most striking discovery involved compounds associated with Acokanthera schimperi, a plant also known as the arrow poison tree. Researchers detected those compounds on several of the weapons recovered from the campsite.

Taken together, the findings suggest that the prehistoric inhabitants of ‘Uruq Aljelibah used composite hunting weapons treated with lethal poison. Such technology would have formed part of the sophisticated strategies employed by people living beside the ancient lake.

The study authors do not currently have direct evidence of an animal being killed with the toxic weaponry. Still, megafaunal remains found at the site show that humans were butchering hippos, ostriches, camels, gazelles, and buffalo.

“The lakeshore preserves evidence of a very different Arabia where freshwater, grasslands and trees supported people and abundant wildlife,” said study author Frans van Buchem.

The weapons were not the only objects carrying traces of plant use. Researchers also discovered tools containing remnants of woody plant material, suggesting that the prehistoric hunter gatherers practiced woodwork and conducted various plant processing activities.

The range of preserved evidence gave researchers an unusually broad view of life at the site. Hunting weapons, animal remains, plant traces, and distinct activity areas appeared together within the archaeological assemblage.

Clarkson highlighted that rare level of preservation, explaining that “archaeological sites this old rarely preserve such a complete snapshot of daily life with hunting weapons, butchered animals, plant processing and tool-making areas all in one place.”

The discoveries offer a detailed picture of prehistoric life at ‘Uruq Aljelibah and expand the understanding of Arabia’s role in early human movement out of Africa. The peninsula was more than a route through which people simply passed.

During humid periods, the region offered habitats capable of sustaining significant human occupation. Freshwater ecosystems supported abundant wildlife, while early humans exploited those resources through composite weapons, plant processing, and other complex survival practices.

The findings reveal how periods of greater moisture transformed parts of Arabia into environments where humans could live and hunt. The study was published in the journal Science.