How do you feel when you look at the image of moldy fruit at the top of this post? Are you disgusted?

How does disgust feel in your body? Is it a queasiness or nausea? Is it the sensation of creepy crawlies? What expression does your face make when you see something disgusting like that photograph?

In “How Disgust Explains Everything,” Molly Young writes about the science of revulsion:

Once you are attuned to disgust, it is everywhere. On your morning commute, you may observe a tragic smear of roadkill on the highway or shudder at the sight of a rat browsing garbage on the subway tracks. At work, you glance with suspicion at the person who neglects to wash his filthy hands after a trip to the toilet. At home, you change your child’s diaper, unclog the shower drain, empty your cat’s litter box, pop a zit, throw out the fuzzy leftovers in the fridge. If you manage to complete a single day without experiencing any form of disgust, you are either a baby or in a coma.

Disgust shapes our behavior, our technology, our relationships. It is the reason we wear deodorant, use the bathroom in private and wield forks instead of eating with our bare hands. I floss my teeth as an adult because a dentist once told me as a teenager that “Brushing your teeth without flossing is like taking a shower without removing your shoes.” (Do they teach that line in dentistry school, or did he come up with it on his own? Either way, 14 words accomplished what a decade of parental nagging hadn’t.) Unpeel most etiquette guidelines, and you’ll find a web of disgust-avoidance techniques. Rules governing the emotion have existed in every culture at every time in history. And although the “input” of disgust — that is, what exactly is considered disgusting — varies from place to place, its “output” is narrow, with a characteristic facial expression (called the “gape face”) that includes a lowered jaw and often an extended tongue; sometimes it’s a wrinkled nose and a retraction of the upper lip (Jerry does it about once per episode of “Seinfeld”). The gape face is often accompanied by nausea and a desire to run away or otherwise gain distance from the offensive thing, as well as the urge to clean oneself.

The more you read about the history of the emotion, the more convinced you might be that disgust is the energy powering a whole host of seemingly unrelated phenomena, from our never-ending culture wars to the existence of kosher laws to 4chan to mermaids. Disgust is a bodily experience that creeps into every corner of our social lives, a piece of evolutionary hardware designed to protect our stomachs that expanded into a system for protecting our souls.

The article goes on to discuss two important research papers on disgust from the Hungarian researchers Aurel Kolnai, whose paper came out in 1929, and Andras Angyal, whose work was published in 1941:

Nonetheless, Kolnai was the first to arrive at a number of insights that are now commonly accepted in the field. He pointed to the paradox that disgusting things often hold a “curious enticement” — think of the Q-tip you inspect after withdrawing it from a waxy ear canal, or the existence of reality-TV shows about plastic surgery, or “Fear Factor.” He identified the senses of smell, taste, sight and touch as the primary sites of entry and pointed out that hearing isn’t a strong vector for disgust. “One would search in vain for any even approximately equivalent parallel in the aural sphere to something like a putrid smell, the feel of a flabby body or of a belly ripped open.”

For Kolnai, the exemplary disgust object was the decomposing corpse, which illustrated to him that disgust originated not in the fact of decay but the process of it. Think of the difference between a corpse and a skeleton. Although both present evidence that death has occurred, a corpse is disgusting where a skeleton is, at worst, highly spooky. (Hamlet wouldn’t pick up a jester’s rotting head and talk to it.) Kolnai argued that the difference had to do with the dynamic nature of a decomposing corpse: the fact that it changed color and form, produced a shifting array of odors and in other ways suggested the presence of life within death.

Angyal argued that disgust wasn’t strictly sensory. We might experience colors and sounds and tastes and odors as unpleasant, but they could never be disgusting on their own. As an illustration, he related a story about walking through a field and passing a shack from which a pungent smell, which he took for that of a decaying animal, pierced his nostrils. His first reaction was intense disgust. In the next moment, he discovered that he had made a mistake, and the smell was actually glue. “The feeling of disgust immediately disappeared, and the odor now seemed quite agreeable,” he wrote, “probably because of some rather pleasant associations with carpentry.” Of course, glue back then probably did come from dead animals, but the affront had been neutralized by nothing more than Angyal’s shifting mental associations.

Disgust, Angyal contended, wasn’t merely smelling a bad smell; it was a visceral fear of being soiled by the smell. The closer the contact, the stronger the reaction.

Students, read the entire article, or at least the first two sections of it (until “I first met”), then tell us:

• What is your reaction to the article? Did you feel disgust while reading any parts of it? Did any of the theories about disgust resonate with you?

• In your experience, what makes something disgusting? Is it the taste, texture, smell or sight of it, as Kolnai argued? Is it the mental associations with it or the fear of being contaminated as, Angyal suggested? Or is it something else?

• Describe in detail something that really disgusts you. Use vivid and descriptive language to bring your revulsion to life. Then, explain why you think this thing is so repulsive to you. (Please keep in mind that your comment should remain appropriate for our site. We won’t approve comments that include obscenity, vulgarity or profanity.)

• Later on in the article, the author suggests that disgust can also apply to a person’s politics, beliefs or activities, such as what a person with conservative politics might feel for someone with liberal politics (and vice versa), or what someone might feel about things like racism, brutality or hypocrisy. Do you agree? Do you ever feel disgust, and use that word, to describe such ideas? Is it the same feeling you might feel for moldy food or garbage? Or is the sensation and meaning different to you?

• The author describes the feeling of disgust as “the energy powering a whole host of seemingly unrelated phenomena … a piece of evolutionary hardware designed to protect our stomachs that expanded into a system for protecting our souls.” What role do you see disgust playing in our society? How has it influenced your own life, if at all?

Want more writing prompts? You can find all of our questions in our Student Opinion column. Teachers, check out this guide to learn how you can incorporate them into your classroom.

Students 13 and older in the United States and Britain, and 16 and older elsewhere, are invited to comment. All comments are moderated by the Learning Network staff, but please keep in mind that once your comment is accepted, it will be made public.