Ancient teeth from Indonesia may show betel-nut use 25,000 years ago, pushing a widespread mind-affecting habit deep into humanity’s hunter-gatherer past.
Researchers found deep, unusual grooves and chemical traces in ancient teeth from Sulawesi, an island in modern-day Indonesia. They say the evidence fits decades of sucking betel nuts.
The remains date as far back as 25,000 years. If the researchers are right, the discovery captures an early form of a habit now practiced by about 600 million people.
A second set of teeth, found about 20 miles east, carried similar marks. Those teeth may be up to 8,000 years old.
The research, led by Griffith University archaeology professor Adam Brumm, was published in Science Advances. The team examined both tooth wear and chemical evidence preserved in dental tissue.
The grooves first caught Brumm’s attention because they did not match ordinary chewing wear. In several teeth, they cut through to the pulp cavity, which holds the tooth’s nerves.
Brumm contacted other archaeologists for possible explanations, but none could account for the marks. As NPR reported, researchers considered food and the use of teeth to process plant fibers.
Brumm described the team’s conclusion this way:
“We think it might have started with hunter-gatherers just sucking on the nuts, almost as though they were gobstoppers.”
The researchers compared the damage with grooves left by long-term clay-pipe use. Habitual smokers could develop round notches where a pipe stem repeatedly rested against their teeth.
The Sulawesi grooves also appear to have formed through repeated contact over decades. Brumm said the ancient people may have been “hooked on nut-sucking.”
The team also tested dental tissue for arecoline, a chemical found in betel nuts. Its presence added a second line of evidence beyond the physical wear.
Brumm then worked with Roger Papke, a University of Florida researcher who studies how drugs affect the nervous system. They tested whether merely sucking a nut could produce a mind-affecting response.
The experiment used artificial saliva and engineered frog egg cells containing human brain receptors. The researchers found that sucking the nut could release chemicals capable of entering the bloodstream and affecting brain function.
Brumm tried it himself. He said gently gnawing the outside released bitter, astringent juice that made his mouth numb.
That numbing effect may explain why hunter-gatherers first adopted the practice. Brumm raised pain relief as one possibility, though the evidence does not establish their motive.
Other cultural or social reasons remain possible. Ancient people did not leave an account explaining why they repeatedly put the nuts in their mouths.
Peter Ungar, a University of Arkansas anthropology professor who was not involved in the study, said the combination of excessive wear and chemical evidence made a strong case.
José Capriles of Penn State University was more cautious. He found the evidence persuasive but noted that the researchers examined only two skeletons.
Capriles said direct evidence would include nuts or seeds found in a clear cultural setting. That kind of discovery could tie the plant more firmly to the people whose teeth carried the grooves.
Princeton University anthropologist Agustín Fuentes also warned against placing modern assumptions about pain and drug use onto ancient cultures. He said the findings fit the broader understanding of betel-nut use, but motives remain difficult to recover.
The stakes extend beyond archaeology. Betel nuts rank behind tobacco, alcohol and caffeine as the world’s fourth most commonly used mind-affecting substance. Long-term use can damage teeth, raise heart-disease risk and lead to oral cancer.
Those modern harms do not reveal what happened to the two ancient people. They do show that an old human habit can carry lasting costs.
Good science should follow the evidence without pretending every gap is closed. The past deserves curiosity, but it also demands humility.
