Researchers have uncovered what may be the earliest known evidence of human psychoactive drug use, traced to ancient foragers on the Indonesian island of Sulawesi who routinely sucked on betel nuts as far back as 25,000 years ago. Analysis of two rare pre-agricultural skeletons — one dated to around 7,000 years old and the other between 16,000 and 25,000 years old — revealed deep, rounded grooves in their teeth along with traces of arecoline, the psychoactive compound found in betel nuts (seeds of the Areca catechu palm, widely chewed across the Asia-Pacific and currently used by an estimated tenth of the global population). Scientists from Griffith University in Brisbane suggest the foragers may have sucked on the hard, abrasive nuts to numb toothache, inadvertently creating a self-perpetuating cycle in which the habit worsened the very pain it was meant to relieve, pushing back the known history of deliberate psychoactive plant use by more than a decade beyond the 13,000-year-old fermented drink traditions previously considered the oldest.