25,000-year-old teeth reveal earliest known evidence of human drug use

Traces of the psychoactive compound arecoline查看药品详情 found in the fossilised teeth of two ancient foragers on the Indonesian island of Sulawesi represent the earliest known evidence of human drug use, dating back as far as 25,000 years. The discovery, published in the journal Science Advances, pushes the documented antiquity of psychoactive substance use back by at least 3,000 years beyond the previous record of 13,000-year-old beer brewing in Israel.

The research, led by Professor Adam Brumm, an archaeologist at Griffith University查看公司主页's Australian Research Centre for Human Evolution in Brisbane, examined skeletal remains of two pre-agricultural foragers unearthed at two separate sites in South Sulawesi. One individual was dated to approximately 7,000 years old, while the more ancient specimen was dated to between 16,000 and 25,000 years old. Both predate the arrival of agriculture on Sulawesi.

Distinctive dental wear points to betel nut (搜索)搜索该药品

Both hunter-gatherers displayed deep, rounded grooves in their teeth, some so severe they would have exposed the dental pulp. "I was thinking, what the hell were these people doing? It's like someone had a drill head shaped like a gobstopper and wore away the inner part of the tooth," said Brumm. An analysis of the marks suggested they had been created by repeatedly sucking on a round object one or two centimetres in size.

Betel nuts, the seeds of the Areca catechu palm, are the world's fourth most widely used psychoactive substance after alcohol, caffeine and nicotine, with an estimated tenth of the global population chewing the seeds. Today, the nuts are typically chewed after being mixed with slaked lime to form a "quid" that enhances the release of the psychoactive drug. The researchers hypothesised that an earlier stage of betel nut (搜索)搜索该药品 use involved simply sucking on the nut itself, before the development of the modern chewing custom.

Experimental confirmation of the mechanism

To test this hypothesis, the team designed an experiment simulating betel nut (搜索)搜索该药品 sucking. They soaked betel nuts in artificial saliva and found that the solution soon contained enough arecoline查看药品详情 to induce a high, albeit a milder one than when the nut is chewed with slaked lime. The researchers then tested the saliva on frog egg cells genetically engineered to grow human brain receptors, and the results suggested that betel nut sucking would affect human brain cells.

"It will alter human brain function, but not to the extent of modern betel nut (搜索)搜索该药品 chewing with slaked lime," Brumm said. Subsequent analysis of the fossil teeth found arecoline查看药品详情, the main psychoactive substance in betel nut, in the tissues.

A self-perpetuating cycle of pain and addiction

The researchers believe betel nut (搜索)搜索该药品 sucking would have produced a numbing effect on the mouth and may have been used as a painkiller. Brumm, who tried the method himself, described a "really bitter, astringent taste" that "makes your mouth go numb." However, the habit would have damaged teeth in the process, producing deep grooves that prompted painful toothaches.

"This might have been a traditional remedy for toothache, but if they did it for too long, sucking on the nut wore down their teeth so badly that it actually created much worse dental pain in the long term," Brumm said. "These individuals were seemingly caught in a self-perpetuating cycle where they were continually sucking on the nuts to treat the tooth pain caused by this nut-sucking habit."

Dr Elisa Guerra-Doce, an associate professor in European prehistory at the University of Valladolid查看公司主页 in Spain, said the study provided "direct evidence of the antiquity of human drug use." She added that the findings "not only represent the earliest known evidence to date of the use of psychoactive plants anywhere in the world, but also demonstrate that the consumption of Areca nuts is a millennia-old tradition dating back to prehistoric times."

Modern-day betel nut (搜索)搜索该药品 use affects the mouth and teeth and has been linked to an increased risk of oral cancer (搜索)搜索该疾病. "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," Brumm said. Dr Sofia Samper Carro, an archaeologist at the Australian National University查看公司主页 who was not involved in the research, suggested the work could help identify even older uses of betel nut or other drugs, noting that even earlier hominids such as Neanderthals may have used natural remedies to fight pain and infection.