Washington, June 1 (IANS): Exploring cannabis use among the Aka foragers, a "pygmy" people of the Congo basin, US researchers have found that the more the hunter-gatherers smoke cannabis, the less they are infected by intestinal worms.

"While the Aka deliberately consume a tea of a local plant, motunga, to fight parasitic infections, they do not think of cannabis or tobacco as medicine," said Ed Hagen, anthropologist from Washington State University.

The findings suggest that they may unconsciously be, in effect, smoking medical marijuana.

"In the same way, we have a taste for salt, we might have a taste for psychoactive plant toxins, because these things kill parasites," Hagen added.

Hagen surveyed almost all of the nearly 400 adult Aka along the Lobaye River in the Central African Republic and found roughly 70 percent of the men and six percent of the women used cannabis.

Stool samples collected from the men to gauge their worm burden found some 95 percent of them were infected with helminths. But those who consumed cannabis had a significantly lower rate of infection.

Researchers are unsure when the Aka might have first smoked cannabis or when it arrived on the continent.

It may have come with traders from the Indian subcontinent around the first century AD, but Hagen and his colleagues said it might not have been smoked until European colonisation in the 17th century.

The study appeared in the American Journal of Human Biology.