Scientists from Washington State University have suggested that smoking cannabis may have a beneficial effect with regard to the avoidance of intestinal parasite infections, which could explain why the drug has such a long history of recreational use. In a press release by the university, lead researcher Ed Hagen from WSU Vancouver is quoted as saying that it is possible for humans to have developed a taste for the toxic plant not for purely recreational reasons but as a prophylactic against intestinal parasites. The basis for this hypothesis comes from the fact that the body reacts to toxic substances not just through the heightened feeling of pleasure. Toxins also provoke a feeling of nausea and can be lethal to parasites.
Hagen studied the Aka hunter-gatherer community that lives in the Central African Republic and, like the few other remaining such communities, provides valuable insight into human evolution. Archaeologists, anthropologists and scientists often study such communities as a means of gathering insights into early hunter-gatherer societies. It is of course a highly speculative way of studying the past, but it is considered a means of observing human societies detached from modern, westernised traditions and practices.
What Hagen and his team found was that 70% of men in the Aka tribe regularly smoked cannabis. As much as 95% of all Aka men were also infected with helminths (intestinal parasitic worms), but those who smoked cannabis had a lower rate of infection. They were all treated with an antihelminthic drug and after 12 months the researchers found that the rate of secondary helminth infection among the pot smokers was significantly lower than in the rest of the Aka men. What’s more, an earlier study by Hagen found that even those Aka men who smoked a lot of tobacco had a lower rate of helminth infection.
The conclusions that could be drawn from the study include the suggestion that the Aka people unconsciously use cannabis and tobacco against parasites, even though they quite deliberately drink tea made from the leaves of a local plant to the same end. Also, if this hypothesis is confirmed, it might offer a whole new perspective on drug use, as an unconscious manifestation of self-preservation rather than as a way of stimulating the pleasure centres of the brain.
Hagen told WSU’s media centre that some animal species are known to use toxic plants as a way of avoiding certain diseases, so there is a kind of precedent. However, he adds, the results of relevant studies are limited. There is evidence that nicotine kills off parasites in animals but the effect of the substance on humans has not been proven directly. Also, while marijuana has been found to be lethal for parasites in the lab, there is no evidence that it is equally lethal to the worms living in the bodies of animals.
It is not clear when the Aka people, who live in the Congo Basin, started smoking cannabis because we don’t know when the plant was introduced in the region. It is possible that it came with traders from India as early as the first century CE but there is also a possibility that it was introduced much later, when the first European colonists arrived in Africa. Whenever this practice started among the Aka, the curious question remains: do people smoke pot just for the pleasure of it, or is it an unconscious way of protecting the body from parasites?