Ice Age Hunter-Gatherers Used Betel Nuts for Toothache

The world's oldest known habitual use of a neuroactive plant drug has been identified in Indonesia. Ice age hunter-gatherers on the island of Sulawesi regularly sucked on betel nuts, likely to soothe toothaches, according to a new study published in Science Advances.

Researchers from Griffith University in Australia analyzed the partial skeletons of two prehistoric individuals found on Sulawesi. Both had distinctive deep grooves in their teeth. Study first author Adam Brumm, an archaeologist, told Live Science that the grooves were caused by a lifetime of sucking on betel nuts. The practice seems to have been a counterproductive remedy. "The more they sucked on the nut to relieve toothache, the worse that the damage to their teeth became," Brumm said. In one individual, the groove exposed the tooth's inner pulp cavity, which would have caused excruciating pain.

The Ancient Individuals and Their Habit

The two individuals lived thousands of years apart. One was a man who died between the ages of 40 and 50. He lived between 25,000 and 16,000 years ago, during the Last Glacial Maximum. The second person, of undetermined sex but similar age at death, lived between 7,600 and 6,300 years ago. The analysis suggests both engaged in the habit almost continuously throughout their lives.

Betel nuts contain the neuroactive compound arecoline. Sucking the nuts directly, as these hunter-gatherers did, would have produced a numbing effect rather than the stimulant effect associated with modern chewing practices. The researchers confirmed the neuroactive potential by testing genetically-engineered frog eggs with human neuroreceptors. Chemical analysis of dental samples also revealed traces of betel nut use.

A Prehistoric Painkiller with Consequences

This finding represents the earliest evidence of habitual drug use from plants. A 2017 study showed Neanderthals used poplar bark, which contains a natural aspirin-like compound, for pain relief. Other prehistoric societies used plant-based drugs, such as a psychedelic cactus in Peru 10,000 years ago and alcoholic beer in Israel 13,000 years ago. However, the Sulawesi evidence pushes the timeline for habitual use back significantly.

The study indicates that this early form of drug use predated the advent of farming. The older individual lived thousands of years before agriculture began in the Fertile Crescent around 12,500 years ago. Archaeologist Elisa Guerra Doce of the University of Valladolid, who was not involved in the study, called it a "fantastic piece of research." She said it provides "particularly compelling and direct evidence for the antiquity of drug use" and reveals the prehistoric roots of a cultural practice now widespread in Southeast Asia and the Pacific.

From Simple Sucking to Modern Chewing

Today, betel nut is used by an estimated 600 million people, primarily in South Asia and Oceania. Modern users typically mix the nut with slaked lime (calcium hydroxide) to create a chewable, stimulant quid that is highly addictive. Arecoline is carcinogenic, and the practice, often combined with tobacco, is linked to mouth cancer diagnoses.

The researchers speculate that the practice of adding slaked lime originated much later, during the Neolithic period on Sulawesi about 4,000 years ago. Slaked lime was initially used in pottery production to prevent shrinking and cracking during firing. "It now seems probable that betel chewing as we know it evolved from a much simpler, older practice of just sucking on the intact nut," the study authors wrote.

Guerra Doce noted that the findings highlight how prehistoric people explored their environment, finding not only food and medicine but also substances that became woven into social traditions. The deep dental grooves likely only became apparent in mature individuals who had become addicted to the lifelong practice of sucking the nuts for relief.