While you might not want to think much about something disgusting, our brain’s disgust response may be more revealing than you know.
Previous blogs have emphasized both the existence of universal basic emotions and the evolutionary basis behind many of our expressions. A recent article in Science helps examine these same evolutionary roots with regard to the feeling of disgust. Here, Drs. Weinstein, Buck, and Young draw parallels between the evolution of disgust and fear based on perceptions of the outside world and exposure to parasites.
In this paper, they outline how our feeling of disgust is situated within a fear of parasites. The threat of parasitic infection carries dangerous and significant risks for any individual, but they are simultaneously very hard to detect. This helps result in a series of indirect, almost heuristic, approaches to detecting them, largely relying on the disgust response.
For example, many species will simply categorically avoid feces and carcasses, sidestepping the entire issue. Others can depend on subtle, implicit cues, to try to figure out if a given carcass is infected, drawing from the chemical changes that result in an infected animal’s sweat or feces.
While these observations may stand alone in interesting ways, the analysis gets more nuanced and informative when compared to the cognitive structures that can help prey detect and avoid predators. Dr. Weinstein and her team describe this as the “predator-induced landscape of fear.”
This phenomenon describes the general outlook that many animals can create, where they integrate cues that may reveal the threat of a predator or similar sorts of stimuli. This integrates olfactory cues, for example, into a holistic way of evaluating the world based on a fear response.
Dr. Weinstein’s paper presents the notion of disgust as being part of an overall “landscape of disgust,” where numerous cues and sensory inputs can all be synthesized into a more comprehensive way of evaluating the world according to the risk of parasites.
These landscapes of disgust and of fear are also not completely different phenomena. Detecting predator feces, for instance, helps integrate both fear and disgust into the same picture. We are definitely hoping for more research that shows how perhaps other emotions are integrated in similar ways. And of course, a greater understanding of these emotions in the human context would be invaluable.
This differs, perhaps, from the way humans see themselves as intellectually evaluating the world around them.
However, psychological research helps connect these ideas with how we, as humans, rely on a complex series of heuristics in order to evaluate the world around us. Over the last two weeks, for example, our blogs have examined heuristics related to deception detection and confirmation bias. These cognitive shortcuts are rooted in survival, where we developed innate abilities to evaluate emotions without cognitive effort.
While these are different than a worldview integrated with fear or disgust, they help demonstrate how humans are not completely different. We still rely on subtle heuristics, just like animals, especially for basic emotions like fear and disgust. And critical thinking requires that we acknowledge and evaluate those heuristics.