[DIGEST: The Conversation, Harvard, IFL Science]

Nancy Reagan may have advised Americans to “Just say NO” to drugs, but her campaign did little to quell the public’s fixation. Banning them, defending them, studying them: we are a drug-obsessed species. It’s not hard to see why. Drugs like cocaine and heroin directly interact with our brains, stimulating the reward center and creating a sense of euphoria. However, psychedelic drugs, also known as hallucinogens, such as LSD and mushrooms, do not impact this same pleasure center, and in fact simply poison the body, which results in vivid hallucinations and altered states of mind. From an evolutionary standpoint, this is puzzling. Why would humans, as a species, embrace something that poses such risk? To understand what role hallucinogens have played in our evolution, scientists have been investigating our cultural history, rather than our physical growth as a species.