Humans may have been using mind-altering substances far earlier than scientists had once thought, new research indicates.

The evidence shows that betel nuts were used as drugs by some Indonesian communities up to 25,000 years ago.

Scientists from Griffith University in Australia found unusual patterns in the skeletal remains of early human foragers, which they linked to the sucking of betel nuts.

Professor Adam Brumm, who led the research, said this may be the “earliest evidence for drug use anywhere in the world”.

In the new study, published in Science Advances, the researchers reported the discovery of rare skeletal remains of two early human foragers from the Indonesian island of Sulawesi. One dated to 25,000-16,000 years ago and the other to 7,600-6,300 years ago.

Both of the hunter-gatherers showed an unusual dental wear pattern with deep, rounded tooth grooves, which the researchers found was caused by sucking whole betel nuts.

When consumed, betel nuts – seeds of the betel or Areca catechu palm – induce a sense of mild euphoria and heightened awareness.

Brumm said: “Although poorly known in western societies, it is the world’s fourth most widely used psychoactive substance, after alcohol, caffeine and nicotine.”

It had previously been thought that drug-taking began after the advent of farming, beginning with fermented alcohol drinks about 13,000 years ago.

However, that theory “fails to account for the possibility that very ancient drug-taking lies at the roots of our most commonly used psychoactive substances”, according to Brumm.

“By identifying the ancient practice underlying betel-nut chewing as we know it, the study implies that some modern drug-taking behaviours are deeply rooted in forager traditions.”

In the modern era, the drug is taken by mixing a processed seed of the betel nut with slaked lime and other ingredients to form a “quid”, which is chewed. The mixture is popular in South and South East Asia, and is chewed by about one-tenth of the globe’s population.

Researchers conducted experiments where they soaked betel nuts in artificial saliva, and found that just sucking on intact betel nuts released enough of the psychoactive compounds to alter brain function.

The effects of sucking betel nuts may have been milder than modern quid chewing, but the team suggested that the habit was significant enough to cause severe gum disease.