Evidence suggests that the use of poison-tipped arrows dates back as far as 60,000 years ago, according to a report by Live Science. Researchers led by Sven Isaksson of Stockholm University identified traces of toxic substances on five quartz arrowheads found at South Africa’s Umhlatuzana rock shelter, a site excavated in 1985. One of the toxins, buphandrine, would have impaired hunted animals, allowing hunters to spend less time and energy pursuing prey. Another toxin, epibuphanisine, was found on only one arrowhead, though researchers believe both substances were likely applied to all of the weapons. Isaksson noted that the poisons may have come from the same plant, Boophone disticha, which grows in southern Africa and is still known today as a source of arrow poison. While humans have long used plants for food and toolmaking, Isaksson explained that this discovery highlights the intentional use of plant chemical properties.