Researchers have identified the oldest known biomolecular evidence of betel nut chewing by analyzing dental calculus from a Bronze Age burial site in Thailand. The study, published in Frontiers in Environmental Archaeology, examined 36 calculus samples from six individuals at Nong Ratchawat, a site dating back around 4,000 years. Chemical traces of arecoline and arecaidine, the active compounds in betel nut, were detected in samples from a single molar belonging to one individual, Burial 11. No tooth staining was present, which the authors attribute to differing consumption methods, post-consumption cleaning practices, or post-mortem degradation over millennia.

The findings matter for dental professionals because they confirm that mineralized plaque can preserve chemical signatures of repeated plant use across thousands of years, even when no visible signs remain on the tooth surface. The research team replicated authentic chewing conditions using dried betel nut, Piper betel leaves, limestone paste, and human saliva to validate their detection method.

For clinical practice, the study illustrates that dental calculus is a biochemical archive. The same analytical approach could, in principle, be applied to understand oral health behaviors in historical populations, and it reinforces how calculus accumulation reflects long-term habitual exposure to specific compounds.