Some 4,000 years ago, a woman in Thailand chewed on the seed of the areca palm fruit, known as the betel nut, and likely felt a high. The practice, which can color the teeth dark red and deliver psychoactive effects, is one that has continued for millennia. People throughout Southeast Asia and the Pacific Islands have long chewed the betel nut and incorporated the practice in traditions, including longevity ceremonies, harvest rituals and coming-of-age rites of passage.
The 4,000-year-old evidence of betel nut-chewing emerged when archaeologists analyzed 36 dental plaque samples from the remains of six people from Thailand’s Nong Ratchawat burial site for a July 2025 study in Frontiers in Environmental Archaeology.
Since this hardened plaque, also known as dental calculus, doesn’t deteriorate, it can preserve clues to what someone may have chewed on in their lifetime. The archaeologists found residual compounds associated with betel nuts in three of the 36 dental calculus samples, all from a single female individual between 25 and 35 years old.
Psychoactive Stimulants in Betel Nut
Chewing betel nut, which often entails preparing the seed with betel leaf, limestone paste and sometimes tobacco, can produce a sense of euphoria and relaxation in the user, according to Piyawit Moonkham, an anthropological archaeology lecturer at Chiang Mai University in Thailand and co-author of the 2025 analysis.
The betel nut is a psychoactive substance and a stimulant that also carries health risks—it is carcinogenic and linked to oral cancers. The paper describes the primary psychoactive compounds in betel nut as arecaidine, guvacine, guvacoline and arecoline, which all act as mild parasympathomimetic stimulants, meaning they mimic the effects of the parasympathetic nervous system.
Betel Nut Chewed as Rite of Passage
Humans haven’t only used betel nuts for the sensation they evoke, but also the physical changes they bring. The teeth staining caused by chewing betel nuts can signify a rite of passage into adulthood, Moonkham says, “sort of like a tattoo.” A 2009 paper details that staining teeth by chewing betel nuts can represent passage into adulthood, even signifying preparation for marriage.
While analysis of the burial site revealed that humans have been chewing betel nuts for 4,000 years, evidence of the plant’s existence dates back more than twice as long. Some of the earliest betel nut plant remains in Thailand, according to Moonkham’s paper, come from burials at Spirit Cave in Mae Hong Son province in Northwest Thailand. The burials date back more than 9,000 years.
The betel nut has also appeared in folklore. A 2008 paper describes the ancient Vietnamese tale Tân lang truyện, which can translate to The Story of Tan [and] Lang or The Story of the Areca Palm Tree, that tells the betel nut’s origin through a tragic story about two brothers and a woman.
Ayurvedic medicine also incorporates chewing betel nuts, referred to as tambula within this tradition. The 2008 paper mentions that Ayurveda’s recommended daily regimens include tambula, which can mix aromatics like cardamom and clove with betel nut and leaf. Betel chewing appeared during the second millennium B.C. in southern India, about 1,000 years earlier than its arrival in northern India, where betel chewing documentation begins after 500 B.C.
At the dawn of the common era, Buddhist culture brought an increased demand for betel nuts and leaves as it expanded northward into Central Asia. According to tablets from the third century in Chinese Turkmenistan, known as the Kharosthi documents, betel components were imported because they couldn't grow locally.
In the 1940s, Thailand’s government began to discourage the use of betel nuts due to associated health risks and to more closely align with Western cultures, according to Moonkham. While betel nuts still play a role in rituals, Moonkham says they’re more prevalent in informal settings, providing “an inclusive activity across social, religious, age or gender barriers.”
