The prehistoric remains of two foragers found on the Indonesian island of Sulawesi contain telltale signs that humans began using a mind-altering drug thousands of years earlier than known. The betel nut, a fruit seed from the areca palm, is considered the fourth most widely used psychoactive substance in the world after caffeine, alcohol and nicotine. About 1 in 10 people today, largely across Asia and the Pacific, practice the tradition of chewing a quid, or processed betel nut mixed with slaked lime. The slaked lime, also known as calcium hydroxide, is essential for triggering a chemical reaction that expedites the absorption of the psychoactive compound arecoline into the bloodstream. Users experience mild euphoria and heightened alertness when chewing the quid. But when did humans first begin experimenting with psychoactive substances? “Archaeologists have long believed that the earliest traditions of drug use arose around 13,000 years ago when nomadic hunter-gatherers began to domesticate plants and live permanently in one place as farmers,” wrote Adam Brumm, professor of archaeology at Griffith University’s Australian Research Centre for Human Evolution, in an email. During this so-called Neolithic Revolution, farmers in what’s now Israel first brewed beer from barley. And betel nut chewing occurred in Southeast Asia as early as 4,000 years ago, previous evidence has suggested. But Brumm’s team has uncovered evidence that prehistoric foragers were sucking on whole betel nuts between 25,000 and 16,000 years ago. The practice could represent the oldest known example of drug use by humans, which evolved into the betel nut chewing that remains so popular today. Brumm, lead author of a new study published Wednesday in the journal Science Advances, and his colleagues believe that while less potent than quids, the whole betel nuts served as a pain reliever — but created a chain reaction that only led to more pain. “The new findings from Sulawesi suggest foraging communities in some parts of the world were not just using plant drugs at a far earlier time,” Brumm said, “they were becoming dependent on their neuroactive properties and suffering from the negative consequences of long-term use.” Fossils with stories to tell Brumm’s team unearthed a set of remains from Leang Bulu Bettue, a limestone cave in South Sulawesi’s mountainous Maros-Pangkep karst landscape, in 2017. The upper jawbone fragment belonged to an adult, determined to be a preagricultural forager, who lived between 25,000 and 16,000 years ago. Three of the teeth were still preserved, and intriguingly, two had deep, rounded grooves, Brumm said. Prehistoric remains don’t preserve well in tropical environments such as Sulawesi, making the jawbone a rare find. A separate research team working about 20.5 miles (33 kilometers) away at a different cave site, Leang Cappolombo, found the remains of another adult forager with the same telltale grooves left on the teeth, but dated to between 7,600 and 6,300 years ago. The discovery was also made in 2017, but Brumm’s team did not get a chance to study the teeth until three years ago. Both individuals were at least 35 years old, if not older, when they died, according to researchers. The pattern of dental wear on the foragers’ teeth didn’t resemble previous evidence of betel nut chewing. Instead, the grooves were likely created due to habitual sucking on hard, round objects such as whole betel nuts, the researchers determined. The team also analyzed the dental tissue and detected traces of arecoline, the main pain-relieving chemical compound from betel nuts. “The foragers had poor dental health, so it is likely that nut-sucking was a traditional medicinal remedy for toothache,” Brumm said. “However, these hard round seeds are abrasive objects. Regularly sucking the nuts for prolonged periods gradually wore down the dentition of the users so severely that the sensitive inner pulp chamber, the ‘living core’ of the tooth, became exposed.” The pain caused by the exposed pulp chambers would have been intense, leading to difficulty eating and inviting infection to spread to the teeth’s roots and even the jawbone, Brumm added. “At this point, we suspect these people were pathologically addicted to betel nut-sucking to treat the oral pain caused by this cultural practice,” Brumm said. “In effect, they were trapped in a vicious cycle.” Without potent slaked lime to activate the nut’s psychoactive high, Brumm and his team questioned what mind-altering effects the foragers might have experienced. The team soaked betel nuts in artificially created saliva — a saline solution combined with enzymes that help break down food — to carry out a biochemical analysis. The scientists tested the resulting “broths” against cloned human receptors — including proteins that regulate neural activity — that had been embedded in frog egg cells. “This showed that just sucking on intact betel nuts will release arecoline in sufficient amounts to have a physiological effect, altering brain function,” Brumm said. Uncovering ancient substance-use traditions The study authors said sucking on betel nuts was a long-standing cultural practice rooted in forager traditions for thousands of years. “The new data puts betel nut sucking into a very different social context,” wrote Dr. Mario Zimmermann, assistant clinical professor at Boise State University in Idaho and archaeologist specializing in paleoethnobotany, in an email. Paleoethnobotany relies on ancient plant remains to identify how people utilized different flora. Zimmermann did not participate in the new study, but he was a peer reviewer during the editorial process. “Our team’s results from last year established early use in a Bronze Age hierarchical society,” Zimmermann said. But the new study provides evidence for habitual use of betel nut among equals, he added. The practice might have evolved into betel nut chewing 4,000 years ago when early Neolithic settlers called Austronesians colonized Sulawesi as farming societies expanded out of Taiwan, the study authors hypothesize. “We think that Austronesian farmers saw the original inhabitants of Sulawesi sucking betel nuts, adopted this practice for themselves, and introduced their own innovation: chewing the nuts with slaked lime,” Brumm said. “Notably, these early farmers used this substance to make pottery.” Brumm tried sucking on a betel nut to see what it was like for prehistoric foragers and called the experience “distinctly unpleasant” due to the astringent liquid released in the process. He did, however, experience a numbing sensation in his mouth, which would have provided the foragers with temporary relief from toothaches — even while causing damage to their dental health. The research helps highlight how consuming nondietary substances has long been a part of the human experience, Zimmermann said. “We don’t just ingest things to quench our thirst and hunger,” Zimmermann said. “For tens of thousands of years humans have been consuming plant and animal products for purposes such as pain relief, endurance, social lubricant, or the immersion in alternate realities.” Now, Brumm wants to explore just how far back other common substance habits go. “Getting drunk on fermented fruits is not even unique to humans — birds do it,” Brumm said. “I suspect that foragers in various parts of the world were making and consuming fermented beverages long before the advent of Neolithic farming around 13,000 years ago.”
