In a groundbreaking revelation that rewrites the history of human hunting technology, researchers have uncovered traces of poison on 60,000-year-old stone arrowheads from South Africa, marking the oldest direct evidence of toxic weapons ever found. This discovery not only highlights the sophisticated ingenuity of Middle Stone Age hunter-gatherers but also provides crucial insights into early behavioral modernity and the deep roots of ethnobotanical knowledge in the region.

The arrowheads, tiny quartz microliths backed for hafting, were excavated from the Umhlatuzana Rock Shelter in KwaZulu-Natal province. Dated to approximately 60,000 years ago during the Howiesons Poort period—a time associated with advanced stone tool technologies—these artifacts reveal a level of planning and chemical understanding previously unattributed to such early humans. The poison, derived from the toxic bulb of the Boophone disticha plant (commonly known as gifbol or poison bulb), contains stable alkaloids like buphanidrine and epibuphanisine that survived millennia due to the site's unique acidic soil conditions.

This find pushes back the confirmed use of poisoned arrows by over 50,000 years, surpassing previous evidence from sites like Border Cave (35,000 years ago) and Kruger Cave (7,000 years ago). It underscores how southern African populations were leveraging nature's pharmacy for survival long before similar practices appeared elsewhere.

Unhlatuzana Rock Shelter: A Window into the Middle Stone Age

Umhlatuzana Rock Shelter, discovered in 1982 and first excavated in the 1980s by Jonathan Kaplan, has long been a key site for understanding the Middle Stone Age (MSA) in South Africa. Located in the lush KwaZulu-Natal Midlands, the shelter spans over 100,000 years of occupation, with layers revealing Still Bay, Howiesons Poort, and later MSA technologies. The Howiesons Poort layer (Layer RBS XX), from which the poisoned arrowheads come, is dated to 60 ± 3.5 thousand years ago using optically stimulated luminescence (OSL), placing it firmly in Marine Isotope Stage 4—a period of climatic instability.

Out of 649 backed quartz pieces recovered, researchers selected 10 with visible residues for analysis. The site's stratified deposits, gradual sedimentation, and low pH (acidic Pleistocene layers) created ideal conditions for organic preservation, shielding the alkaloids from degradation. This contrasts with alkaline Holocene layers where preservation is poorer, explaining why earlier Holocene poisons are better documented.

The shelter's history includes evidence of heat-treated silcrete tools and ostrich eggshell beads, hallmarks of symbolic behavior, making it a hotspot for studies on MSA innovation.

Microlithic Arrowheads: Precision Engineering of the Stone Age

The arrowheads are backed microliths—small (under 2 cm), sharp quartz segments with one blunted edge for hafting into arrow shafts. Microscopic examination revealed impact fractures, spin-off scars, and striations consistent with projectile use, specifically transverse hafting where the tip hits prey sideways to maximize penetration and poison delivery.

Quartz was chosen for its sharpness and brittleness, ideal for detaching in wounds and lodging barbs. Adhesives, likely plant resin mixed with ochre and fat, secured them to wood shafts. This technology mirrors Holocene San arrows, suggesting continuity in design for poison application—small wounds suffice for toxin entry, avoiding the need for large impacts.

In the Howiesons Poort, such microliths represent a shift to composite tools, requiring foresight in hafting, poison sourcing, and tracking wounded game over distances.

Advanced Chemical Detective Work Reveals Ancient Toxins

The breakthrough came from gas chromatography-mass spectrometry (GC-MS), a technique separating and identifying compounds in minute residues (<100 μg). Led by Sven Isaksson at Stockholm University, the team derivatized samples minimally destructively, comparing them to ethnohistorical arrows (1772-1774 CE) and fresh Boophone disticha exudate.

Five of 10 microliths yielded buphanidrine (match scores 682-873) and epibuphanisine (729), crinane-type alkaloids unique to southern African Amaryllidaceae. Fatty acids like palmitic (plant-derived) confirmed hafting residues. NIST database matches exceeded 900 for excellent identification, ruling out contamination.

"The poison takes time to have an effect, so the hunters had to understand cause and effect and plan ahead," Isaksson noted, emphasizing the cognitive demands.

Boophone disticha: The Gifbol Plant and Its Deadly Legacy

Boophone disticha, or gifbol (Afrikaans for "poison bulb"), is a hardy geophyte with a spiral trunk and red flowers, native to southern Africa's grasslands. Its bulb exudate yields neurotoxic alkaloids causing paralysis, convulsions, and death via muscle relaxation—perfect for delaying prey escape without spoiling meat.

San and Khoi hunters historically scraped the milky gum, drying it into a paste applied to arrowheads. Ethnobotanical records from 1770s explorers like Carl Peter Thunberg confirm its use, with poisons remaining potent after centuries. Modern San still employ it, mixing with other plants for potency, though single-component use at Umhlatuzana suggests early simplicity evolving to complexity.

The plant's range overlaps the site, thriving in MIS 4 conditions, indicating ancient knowledge of foraging, extraction, and dosage.

From Persistence Hunts to Poisoned Precision: Hunting Revolution

Middle Stone Age hunters likely combined poison with persistence hunting—tracking exhausted animals over hours. Slow-acting toxins induced nausea and weakness, turning minor hits lethal. This efficiency boosted calorie intake, supporting population growth and brain evolution.

Marlize Lombard (Univ. Johannesburg) highlights: "It takes a developed working memory to predict that if I put this arrowhead into that plant, it will shorten the delay before I get my hands on this meat." Compared to thrusting spears, bows and poison enabled safer, distant kills against dangerous game like buffalo.

South Africa's MSA sites like Sibudu show bow-and-arrow evidence ~64 ka, aligning with poison innovation.

Behavioral Modernity: Cognition in the Cradle of Humankind

Howiesons Poort (65-55 ka) marks a 'creative explosion' with heat treatment, shell beads, and engravings—proxies for symbolism and planning. Poison use demands multi-step reasoning: plant identification, toxin extraction, testing, application, and prey tracking.

This challenges Eurocentric views of modernity originating ~50 ka, affirming southern Africa's role. Lombard notes it evidences "cumulative culture" where innovations built iteratively.

Stats: ~10% MSA sites show backed tools; poison elevates Howiesons Poort's uniqueness.

The Preservation Puzzle: Why Did the Poison Survive?

Alkaloids' stability—lipophilic, rigid structures—resists hydrolysis. Site's acidic pH (~5), low moisture, and quartz's inertness prevented breakdown. Modern analogs: B. disticha poison active after 100 years on arrows.

Future analyses could target younger layers for recipe evolution.

Behind the Science: An International Team's Triumph

Co-led by Sven Isaksson (Stockholm), Marlize Lombard (Univ. Johannesburg), Anders Högberg (Univ. Johannesburg), the team used non-destructive sampling. Lombard, MSA expert, contextualized artifacts; Isaksson's residue expertise unlocked secrets.

Funded by Swedish Research Council, published Science Advances Jan 2026. Collaboration exemplifies global archaeology.

South Africa's Rich Archaeological Tapestry

Blombos Cave (shell beads 75 ka), Diepkloof (engraved ostrich eggs 60 ka), Sibudu (bone tools 77 ka) complement Umhlatuzana, painting MSA as innovation hub. Poison fits pattern of symbolic, technical advances.

Challenges: Looting, climate change threaten sites; funding lags despite UNESCO status.

Photo by Stephan Nell on Unsplash

Future Horizons: What Lies Ahead

Researchers plan proteome/metagenome analyses for recipes, protein sequencing for prey blood. Implications for ethnobotany, toxicology, evolution. Lombard: Opens "doors for more research on toxin survival."

In SA universities like Johannesburg, this boosts archaeology programs, attracting global talent.

For more on SA research careers, explore opportunities at local institutions.