A team of archaeologists has uncovered evidence that humans may have used psychoactive substances as far back as 25,000 years ago, much earlier than previously thought. The study, led by Professor Adam Brumm from Griffith University's Australian Research Centre for Human Evolution (ARCHE), involved researchers from ARCHE, Indonesian archaeologists from Makassar's University of Hasanuddin, and the National Research and Innovation Agency (BRIN). The research focused on the origins of betel nut use, a practice that is still common today in parts of South Asia and Oceania. The study reports the discovery of skeletal remains of two early human foragers from the Indonesian island of Sulawesi. One individual dates back to 25,000–16,000 years ago, and the other to 7,600–6,300 years ago. Both showed unusual dental-wear patterns, with deep, rounded grooves on their teeth. Researchers believe these patterns were caused by the habitual sucking of whole betel nuts. This practice may have been used to relieve tooth pain, but it ultimately led to significant dental damage. Chemical analysis of the dental tissues revealed traces of arecoline, a psychoactive compound found in betel nuts. To confirm their hypothesis, the team conducted experiments in which they soaked betel nuts in artificial saliva and tested the resulting liquid against human neuroreceptors. Their results showed that sucking on intact betel nuts could release enough arecoline to have a physiological effect. The findings challenge the long-held belief that the earliest use of psychoactive substances began with the Neolithic era, around 13,000 years ago, when farming and fermented alcoholic drinks emerged. Instead, this study suggests that the use of betel nuts predates agriculture and may represent the earliest known evidence of habitual drug use in human history. Dr. Elisa Guerra-Doce, a prehistoric archaeologist at the University of Valladolid in Spain, called the study "particularly compelling and direct evidence for the antiquity of drug use," highlighting its importance in understanding the deep cultural roots of betel nut use in Southeast Asia and the Pacific.