Teeth uncovered in Indonesia that are up to 25,000 years old show signs of the person having sucked on whole betel nuts, probably to release pain-relieving compounds. The finding represents the oldest archaeological evidence of habitual drug use in humans, dating back even further than the earliest-known beer-brewing. The genome of a long-extinct ancient human is hiding within us About 10 years ago, Brumm and his colleagues were excavating a cave in Maros-Pangkep on the island of Sulawesi in Indonesia when they discovered a fragment of human jaw bone with three teeth.
Dating methods revealed it to be 16,000 to 25,000 years old. These teeth were part of a more complete skull that appeared to have belonged to a middle-aged or older man. The rounded grooves were consistent with repetitively moving a hard, spherical object back and forth inside the mouth, and probably sucking and gnawing on it.
This must have been done on a regular basis, because the teeth were so worn down in some places that their nerve centres were exposed, which would have caused severe pain, says Brumm. The damage reminded Brumm of 19th-century clay pipe smokers whose teeth also became badly worn down from clamping pipes in their mouths for long periods. This led him to speculate that the damage in the ancient teeth might also be related to a substance addiction.
One possibility was an addiction to betel nuts, since they are a popular stimulant in Indonesia and many other parts of Asia. However, the modern practice doesn’t leave rounded grooves in the teeth because the betel nuts, which are actually seeds from the fruits of areca palm trees, are sliced up and mixed with a substance called slaked lime. This enhances the release of stimulatory compounds, including one called arecoline.
The mixture is then chewed, leaving different wear patterns on people’s teeth. Brumm wondered whether simply sucking on whole betel nuts was a precursor to this modern practice. As a preliminary test, he tried rolling a whole betel nut around inside his own mouth, gently sucking and gnawing on it.
He found that “there was a bitter, astringent taste that made my mouth go numb”. The researchers then soaked whole betel nuts in artificial saliva and added the resulting liquid to cells engineered with human brain receptors. This confirmed that sucking on whole betel nuts would release enough arecoline to have physiological effects.
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