Betel nut traces in 25,000-year-old teeth point to early human drug use

Traces of betel nut in 25,000-year-old teeth is earliest-known evidence of human drug use In short: Archaeologists have found evidence of a person who used a psychoactive drug up to 25,000 years ago. Tooth fossils in Indonesia suggest that ancient foragers in the region were sucking on betel nut, possibly as a painkiller. What's next? Human drug use is probably older than this sample, but evidence is harder to come by. Betel nut, one of the most commonly used drugs in the world, appears to have an ancient history. Fossilised remains of two people, found by archaeologists on the island of Sulawesi in Indonesia, carry traces of the psychoactive substance in their jaws. One of the fossils is dated between 16,000 and 25,000 years old, making it the oldest known example of human drug use by at least 3,000 years. The discovery was published today in the journal Science Advances. Adam Brumm, lead author of the study and an archaeologist at Griffith University, said the two people probably sucked on betel nuts like "gobstoppers". Professor Brumm, who tried the method himself, said it had a numbing effect on the mouth. "I suspect that was the effect that they were after," he said. Mysterious damaged teeth in Sulawesi caves The fossils were uncovered by a team of Indonesian and Australian archaeologists at two separate sites in South Sulawesi. Both individuals, the younger of which was 6,300 to 7,600 years old, predate the arrival of agriculture on Sulawesi. Both hunter-gatherers had puzzling, deep marks on their teeth. "Although they were separated by about 10,000 years of time, they had these really distinctive and very unusual tooth grooves," Professor Brumm said. "We couldn't explain them." An analysis of the marks suggested they had been created by repeatedly sucking on a round object, one or two centimetres in size. "I thought, immediately, betel nut is the most likely possibility," Professor Brumm said. Betel nut by another method Betel or areca nut is the seed of a palm native to South-East Asia. It is one of the most commonly used psychoactive substances in the world, alongside alcohol, caffeine and nicotine. Today, people typically grind betel nut and mix it with substances such as slaked lime to enhance its psychoactive properties before chewing it. "We hypothesised that prior to the development of the betel nut chewing custom, there may have been an earlier stage in the human use of betel nut where they just sucked on the nut itself," Professor Brumm said. To test this, the team designed an experiment to simulate betel nut sucking. They soaked betel nuts in artificial saliva, then tested the saliva on frog egg cells, which had been genetically engineered to grow human brain receptors. The results suggested betel nut sucking would affect human brain cells. "It will alter human brain function, but not to the extent of modern betel nut chewing with slaked lime," Professor Brumm said. The team then investigated residues on the fossil teeth, finding arecoline, the main psychoactive substance in betel nut. Sofia Samper Carro, an archaeologist at the Australian National University who was not involved in the research, agreed with the conclusion that betel nut sucking caused the tooth marks. "The early evidence of drug consumption presented here predates any published evidence by thousands of years,"Dr Samper Carro said. Previously, the oldest known evidence of drug use was 13,000-year-old beer brewing in Israel. A painful, addictive treatment The researchers believe betel nut sucking would have produced a numbing effect on the mouth, and may have been used as a painkiller. But betel nuts would have damaged teeth in the process, producing deep grooves that would have prompted painful toothaches. Professor Brumm suggested the damaged teeth were evidence of a "vicious cycle". "The more they sucked the nut for pain relief, the worse it damaged their teeth and the more they became addicted to sucking the nut to treat that." Modern-day betel nut use also affects the mouth and teeth, and has been linked to an increased risk of oral cancer. "You can see the pretty serious negative health consequences and how humans have grappled with those for at least 25,000 years on this island," Professor Brumm said. Dr Samper Carro said the research could help identify even older uses of betel nut or other drugs. "I'm convinced that even earlier hominids, such as Neanderthals, would have used natural remedies [like plants, natural compounds and maybe even insects or fungi] to fight pain and infection," she said. Professor Brumm agreed the practice probably stretched further back into history than their 25,000-year-old sample. "There's no human society today that doesn't use drugs of some kind,"he said. "But we just know so little about the deep antiquity of these practices."