By Maddie Critz, '20
Humans weren’t the first to meet Lucy in the Sky with Diamonds. Hallucinogenic drugs, be they magic mushrooms, blowfish, or moss, have played a role in the animal kingdom since long before the dawn of man. Animal models of hallucinogen use provide key insight into human behavior, drug interaction, and neurological disorders.
Numerous species across the animal kingdom engage in recreational hallucination. Bighorn sheep in the Canadian Rockies deviate from their regular migration patterns to lick a magic lichen with hallucinogenic effects (1). Jaguars of the Amazon have been seen chewing on the roots of the yage plant, a titular ingredient in the making of ayahuasca (A naturally hallucinogenic plant blend used in many early human rituals) (1). Bottlenose dolphins have famously been spotted puffing on a blowfish that releases a psychoactive neurotoxin, inducing “tranquil and strange” behavior (2). Further, many ancient myths across the world depict the discovery of hallucinogenic plants as an animal introducing them to humanity. But why did these behaviors evolve in the first place? When we pose the question “why do humans trip on drugs?” the answer is usually “for fun!” Maybe these dolphins, jaguars, and sheep are simply enjoying that euphoric high. Or perhaps, there’s something more than euphoria driving that evolution: a long-term cognitive benefit.
But first, let’s break down the immediate effects of hallucinogens. Most hallucinogenic plants contain psilocybin, which binds to receptors and prevent the re-uptake of the neurotransmitter serotonin. In short, serotonin saturates the cognitive system, propelling users into a dreamlike state by facilitating brand-new, long-range connections between brain regions (3). Psilocybin in particular can also inspire feelings of intense emotion, including joy. In addition to inducing this euphoria, hallucinogenic experiences in humans have been reported as overwhelming, spiritual, and life-altering (4).
But are the temporary effects enough to keep the bighorn sheep deviating from their migration patterns? Or perhaps is there a long-term advantage? In a 2016 study reviewed in the Brazilian Journal of Psychiatry, researchers demonstrate how harmaline, a derived form of the psychoactant ayahuasca, can cure long-term depression and compulsion in rats. By creating a rat model of depression and dosing the depressed rats with harmaline, they observed a significant and positive change after the dose, with no apparent side effects (5). This change manifested as an increase of exploratory and excited behavior, a healthy increase in appetite, and a normalization of neurotransmitter regulation, all of which lasted for weeks after the dosing (5). These findings suggest a link between psychoactive, hallucinogenic drugs and the treatment of depressive symptoms.
Animal studies such as this provide insight by quantifying and specifying the behavioral and neurochemical effects of psychoactants. In contrast, human studies of hallucinogens are extremely variable person to person, and the long-term benefits prove difficult to assess. The application of animal studies lies in making the direct connection between evolution and human health. Uncovering the evolutionary motivation behind hallucinating among animals as well as the long-term cognitive benefits of psychoactants in animal models illuminates the possible utility of hallucinogens in treating mental health.