Ancient Teeth Grooves Point to Early Betel Nut Use, Study Finds

Adam Brumm, a professor of archaeology at Griffith University in Australia, led the research. 'It's a chance archaeological discovery that reveals an initial stage in the development of this common drug used today,' Brumm said. 'We think it might have started with hunter-gatherers just sucking on the nuts, almost as though they were gobstoppers.'

Betel nuts are the brownish green seeds of certain palm trees, about the size of a walnut. Users say they provide relief from indigestion, fresh breath and an energy boost. The medical community notes that long-term use can damage teeth, increase the risk of heart disease and lead to oral cancer because of the chemicals in the nuts. Betel nuts are considered the world's fourth most commonly used mind-affecting substances, after tobacco, alcohol and caffeine.

Brumm and his colleagues excavated very old human remains on Sulawesi. One set belonged to a hunter-gatherer who lived as far back as 25,000 years. About 20 miles to the east, they found a second set of teeth from a human who lived up to 8,000 years ago. Both had similar strange grooves. Brumm said the grooves were so deep that they had exposed the pulp cavity, the nerve center, of several teeth, a pattern that likely took decades of repeated wear to form.

The team emailed other archaeologists, including what Brumm called all of the world's leading experts in ancient dental wear, but none could explain how the grooves formed. The researchers ruled out known uses of teeth by hunter-gatherers, such as holding, breaking or stretching things, as well as any type of food they might have eaten or the possibility that they were processing plant fibers to make string in their mouths.

Brumm then recalled a different example of distinctive tooth wear from the colonial period in Europe, America and Australia. Laborers who habitually smoked tobacco from clay pipes developed a perfectly round notch in their teeth, he said, because they held the pipe in their mouths Popeye-style over a lifetime. The Indonesian grooves, the researchers thought, might come from a similar cultural habit.

In Asia and the Pacific today, betel nuts are commonly chewed with other chemicals for their combined stimulant effects. But the wear patterns on the ancient teeth were consistent with sucking, not chewing, hard, round abrasive objects over many years, Brumm said. He and his colleagues think they have uncovered an early developmental stage in the practice. 'We think they were hooked on nut-sucking,' Brumm said.

Because sucking betel nuts is not common today, Brumm partnered with Roger Papke, a neuropharmacological researcher at the University of Florida, to test whether the action could cause a drug effect ancient humans may have desired. They soaked whole betel nuts in artificial saliva and introduced the resulting extracts into frog egg cells engineered to produce human brain receptors. Brumm said the artificial saliva successfully extracted arecoline, an active chemical in the betel nut, and the brain receptors turned on when they touched the saliva. 'We've shown that if you just suck on the nut, there's a physiological reaction that can be released into your bloodstream and then into your brain, and that can alter human brain function,' he said.

Outside researchers find the evidence compelling but not conclusive. José Capriles, an associate professor of anthropology at Penn State University who has found drugs used by humans a thousand years ago in South America, said drug use has longstanding and deep roots among humanity. The instinct to experiment and expand horizons with substances is part of human nature, he said.