4,000-year-old teeth record the earliest traces of people chewing psychoactive betel nuts In south-east Asia, betel nut chewing has been practiced since antiquity. The plants contain compounds that enhance the consumer's alertness, energy, euphoria, and relaxation. Although the practice is becoming less common in modern times, it has been deeply embedded in social and cultural traditions for thousands of years. Chewing betel nuts typically results in dark, reddish-brown to black-stained teeth.
https://phys.org/news/2025-07-....year-teeth-earliest-