Ancient human remains from Sulawesi suggest people were habitually using the psychoactive betel nut as far back as 25,000 years ago. Researchers found both unusual tooth wear and traces of arecoline, the nut’s mind-altering compound, in the teeth of prehistoric hunter-gatherers. The practice may have started partly as pain relief for toothaches, but prolonged use severely damaged their teeth. The discovery could represent the earliest known evidence of habitual drug use anywhere in the world.