Why Do Some Things Make Us Feel Disgust?

So picture this: Just yesterday, you read a news story that warned people about a massive uptick in COVID in your state. You're not quite ready to find your old masks, but you make a mental note for sure. Today at work, you find yourself sitting at your usual seat at a weekly team meeting. Your co-worker, Huey, is sitting to your right, as usual. Huey is one of your best friends at work and you don't think a thing.

Until Huey coughs. Loudly and uncontrollably.

You find yourself, as if automatically, moving your chair slightly away from Huey. As your supervisor gives a slide presentation on some new initiative that was handed down by Corporate, Huey coughs wildly again. Oh my goodness! you say to yourself. It is on my computer, my mouse, and...wait, what?! Ew—it is on my hand. MY HAND!!! you scream (silently) to yourself.

As politely as you can, you excuse yourself from the meeting and beeline to the bathroom. You find yourself washing your hands as if your life depends on it. And perhaps it does.

The Behavioral Immune System

One of the great things about the evolutionary perspective in the behavioral sciences pertains to how truly ubiquitous the applications of evolutionary science are across the human experience (see Geher, 2014). While many people are aware of evolutionary applications of such topics as human mating (e.g., Buss, 2017) and prosocial behavior (e.g., Wilson, 2019), in fact, there is a massive body of work applying evolutionary principles to nearly all facets of the broader human experience. This includes work on such topics as health (see Nesse & Williams, 2004), education (see Gruskin & Geher, 2018), warfare (see Smith, 2008), politics (see Bingham & Souza, 2009), and more.

One area of evolutionary psychology that is sometimes overlooked pertains to what is called the behavioral immune system (Schaller, 2006). The basic idea here is equal parts simple and profound. This behavioral system can be defined basically as a set of behavioral and psychological attributes that have the function of reducing our exposure to dangerous pathogens. From this perspective, we can think of the physiological immune system as a subset of a broader immune system that includes a whole suite of behaviors that evolved to protect us from pathogens.

Examples of the behavioral immune system in action can be found in the following:

• People across the globe tend to be disgusted by such stimuli as feces and vomit; stimuli that likely are loaded with pathogens (see Barkow et al., 1992).
• Seeing someone vomit often leads to nausea and possibly to a sort of contagious vomit—an adaptive response that may rid one's body of pathogens that might be found within a group in some localized context (see Tybur et al, 2013).
• People are often grossed out by blood and other bodily fluids—fluids that may contain all kinds of pathogens (see Curtis et al., 2011).
• People are often grossed out by open lesions on someone's body—and it is easy to see how disgust to such stimuli may have adaptive outcomes (Pipitone & DiMattina, 2020).

And more.

Bottom Line

So next time someone accidentally coughs on you and you find yourself totally grossed out, don't feel bad about that feeling! While Huey didn't mean to cough on you during the meeting, this outcome would naturally activate anyone's behavioral immune system—and it is likely that in the age of COVID, behavioral immune systems of people all around the globe are working in overdrive.

The experience of disgust is a highly universal, natural, and adaptive emotional and physiological experience. Perhaps this is why disgust was included in Paul Ekman's famous model of the basic human emotions (see Ekman et al., 1969). Disgust is hardly pleasant—but without it, we might find ourselves facing all kinds of adverse health-related consequences—including death.

So next time that you feel disgusted by something, instead of focusing on the negative feelings associated with disgust, maybe step back and thank your behavioral immune system. When thought about from an evolutionary perspective, it's actually a fantastic adaptation.