Betel nut is the seed of the areca palm, Areca catechu. About one in ten people in the world use it today, which makes it the fourth most used mind-altering substance after alcohol, caffeine and nicotine. It brings on a mild euphoria and makes people feel more alert. Until now the betel habit was thought to have started around 3,500 years ago, in the Neolithic or the Bronze Age.
A team led by archaeologist Adam Brumm at Griffith University in Australia, working with Indonesian archaeologists from Hasanuddin University in Makassar and the national research agency BRIN, pushed that date back a long way. They studied the remains of two foragers from the island of Sulawesi. One lived between 16,000 and 25,000 years ago, during the last Ice Age. The other lived between 6,300 and 7,600 years ago. The study came out in Science Advances in September 2026.
Both people had the same odd wear on their teeth: deep, rounded grooves. People who use betel today usually chew a quid, the processed nut mixed with slaked lime made from ground burnt shells and a few other things. These grooves pointed to something else, whole nuts held and sucked in the mouth day after day for years. Chemical tests then found arecoline, the nut's main active compound, inside the dental tissue of both people.
That left a question. Does sucking a whole nut, with no lime, release enough of the drug to feel anything? The team soaked betel nuts in artificial saliva and tested the liquid on human receptors grown in frog egg cells. It did: the nuts gave off enough arecoline to have a real effect on the body.
The habit had a price. The grooved teeth came with severe gum disease, and some were worn down until the pulp inside was exposed. Arecoline also eases pain, so the researchers describe a loop in which the habit damaged the teeth and the nut soothed the pain it helped cause. Brumm points out that it started long before farming, which may make it the earliest evidence of drug use anywhere in the world.
