Traces of plant poison have been identified on 60,000-year-old Stone Age arrowheads excavated from the Umhlatuzana Rock Shelter in KwaZulu-Natal, South Africa. This discovery represents the oldest direct evidence of arrow poison found globally to date, indicating advanced hunting strategies and cognitive abilities in early human populations in southern Africa. The findings were published in the scientific journal Science Advances.
Discovery Details
The identified poison originates from the South African plant Boophone disticha, commonly known as gifbol or poison bulb. This plant is still utilized by traditional hunters in the region for similar purposes today. Chemical analysis, conducted by a collaborative team of South African and Swedish researchers, revealed the presence of alkaloids, specifically buphanidrine and epibuphanisine, which are characteristic compounds of Boophone disticha.
The arrowheads, described as quartz arrowheads or backed microliths, were excavated in 1985. The presence of these tools during the Late Pleistocene suggests an understanding of plant properties by hunter-gatherers.
Chemical Analysis and Persistence
Chemical analyses were performed on 10 quartz arrowheads, with the alkaloids buphanidrine and epibuphanisine detected on five samples. The low water solubility of these alkaloids is believed to have contributed to their preservation over thousands of years within the buried artifacts.
Sven Isaksson, a professor of archaeological science at Stockholm University and lead author of the study, noted that even in small quantities, the plant's toxins can be lethal to rodents within 20 to 30 minutes. In humans, exposure to these toxins can cause symptoms such as nausea, respiratory paralysis, lung edema, and a feeble pulse.
Hunters may have applied the poison to the arrow points by directly stabbing the gifbol plant's bulb or by extracting and concentrating the poisonous substance, potentially using heat or sunlight. Poisons can operate via various mechanisms, such as myotoxins, which destroy muscle tissue, or neurotoxins, which affect the nervous system. Some toxins are primarily dangerous when entering the bloodstream and may not be harmful upon ingestion, while others can be neutralized by cooking.
Implications for Human Cognition and Technology
The identification of these substances on 60,000-year-old artifacts indicates that people in southern Africa possessed knowledge of toxic substances and their application in hunting millennia ago. The use of poisoned arrows would have reduced the time and energy required for hunters to track and exhaust wounded prey during persistence hunting.
Researchers suggest that the application of arrow poison implies advanced planning, patience, and an understanding of cause and effect. Understanding the delayed effects of a substance applied to an arrow demonstrates complex cultural knowledge, advanced cognitive abilities, and developed hunting practices in prehistoric humans.
Justin Bradfield, an associate professor at the University of Johannesburg’s Paleo-Research Institute, who was not involved in the study, commented on the significance of this direct chemical verification, which supports archaeologists' previous inferences about early human knowledge of plant toxins for hunting.
Historical Context and Previous Findings
For comparative analysis, researchers also examined four 250-year-old arrowheads collected in South Africa during the 18th century. These historical samples also contained the same toxic alkaloids, supporting a continuity of knowledge regarding the use of gifbol as an arrow poison in the region. Isaksson stated that finding identical poisons on both prehistoric and historical arrowheads confirmed the stability of these substances over extended periods.
Prior to this discovery, the earliest direct evidence of poison on hunting tools included bone-tipped arrows from an Egyptian tomb (dating 4,431 to 4,000 years Before Present) and from Kruger Cave in South Africa (approximately 6,700 years Before Present). Other related evidence from Border Cave in South Africa includes an applicator for poison on arrow tips dated to 24,000 years ago and a beeswax lump from 35,000 years ago, potentially used as an adhesive.
Ludovic Slimak, an archaeologist at the French National Centre for Scientific Research and Paul Sabatier University, who was not part of the research, commented that the study supports the view of the bow as a fundamental and complex technology with origins dating back at least 80,000 years in Africa and Asia, accompanying the spread of Homo sapiens.
Future Research
Sven Isaksson and his collaborators plan to investigate additional sites in South Africa to further determine the extent of poison arrow use during that ancient period.