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You Make Me Sick

We’ve all expressed strong feelings about something or someone with expressions like “you smell,” “you make me sick,” or “you make me want to puke.” We may stick out our tongues at someone. One of the strongest expressions of contempt is to spit in someone’s face. What is interesting s how such emotion, and such judgments, especially ones that really have little to do with gustatory experience, with smelling and tasting, are tied to these proximal senses. These are the senses that actually require bodily contact with chemicals in the senses of smell and taste, or of objects or persons with the bodily surface in touch. Human beings tend to live their conscious lives, certainly the parts that have to do with language and story, in terms of the distal senses of sight and hearing, which gives us advantages as what Daniel Dennett once called “anticipation machines,” being able to detect and act on distant objects and events, including ones currently outside our ken. Most of the mammalian kingdom lives largely in a world of smell, but we humans do much to hide or conceal smells, especially those tied to bodily function. But how central might they be to our lives, to how we think about ourselves and our place in the world, and among other people, how we experience some of our most powerful emotions, and some of the ones most tied to our moral judgement.

Looking at the overall dynamics of brain function, Walter Freeman (2000) treats the dominant mammalian sense, olfaction, not as a special case but as paradigmatic, the entorhinal cortex, interacting with many parts of the brain, and including input-output connections with all primary sensory areas, being the main source of input to the hippocampus. The hippocampus is a cortical structure, buried like fingertips in a fist deep inside the medial temporal cortex, one element of the limbic system (which is the substrate of most of our emotional life), with a central location, a long phylogenetic history like the hub of a spider-web connected to memory and central processing. In simple vetrebrates, still goal-directed free-ranging animals, the limbic system is the entire forebrain. Freeman locates this organization as the center to goal-directed activity, with a proprioceptive loop that includes the body, and a motor loop that includes the environment. He holds that hippocampal neural populations with a field of synaptic connections which continually directs behavior interactively with the sensory and motor cortices in the brain as the animal moves to different places in its environment. The brain is deeply rooted in such actions, its neurodynamics organized around them, and its cognitive abilities both built from such connections, and deeply, even if sometimes indirectly, in service of them. The entorhinal cortex, deep in the brain, is where the processing of olfactory information begins, our chemical senses not being routed through the thalamus poised on top of the brainstem, and the primary staging area for all the other senses, en route to cortical processing and conscious awareness. In the rest of the mammalian kingdom, with olfactory dominance and “sense of self” must then be rooted in the entorhinal cortex. Maybe beneath the level of the stories we tell ourselves, and the depictions of how we sound and how we look, is a deeper sense of ourselves tied to our proximal senses, and the sense of our own bodies. Mothers can recognize an article of an infant’s clothing buy smell, as lovers can identify each other. Heat-reduction sweat, effort sweat, fear sweat, and sex sweat are also chemically different, and there is some evidence that we can smell chemical differences from a range of emotions. Do you remember what your thumb tastes like, or even a kiss? What smells like teen spirit? A baby’s head smells like world peace.

What is interesting about disgust is that it isn’t just about disliking how something smells or tastes, but about active revulsion, particularly at the oral incorporation of offensive objects, but it can also include a rejection of touch. This includes animal products, human body fluids and wastes, as well as signs of death and decay. I remember the strong revulsion, almost tinged with metaphysical fear, toward a half-rotted deer carcass on the Appalachian Trail. Eww, gross.

Now, disgust toward feces or rotten meat, or a range of other tastes and smells makes evolutionary sense in protecting health. Our particular facial reaction, often including sticking out the tongue, turning away from an object, and refusing to taste or even touch it make sense, as does even a slight decrease in heart rate (which might slow the metabolism of something poisonous). There may be physical feelings of nausea or in extreme cases, even vomiting. Again, these make sense in terms of avoiding, or getting rid of unhealthy substances. But disgust also gets extended to more abstract moral judgments. The problem is that disgust is hard to reframe -- it is not as “cognitively penetrable” as other emotions that may be altered by thinking about things differently.

What is worse is that it isn’t just bad taste or smell, but a rejection can be extended to the very thought of certain objects (insects, an animal carcass, bloody body parts, corpses -- what does a battlefield smell like at the end of a battle?), and it isn’t altered by changing one’s understanding of the taste or smell. You shouldn’t talk about some things while people are eating. Are you more likely to eat cicada larvae even after you are told they taste like avocado? Not without overcoming your sense of revulsion. What about raw fish? Cultural variations clearly suggest a role for learning and interpretation. As a midwesterner whose exposure to fish was limited to fish sticks on a Friday night, it wasn’t until adulthood, and living near a coast, that I learned it is only fish that has begun to decay that has that “fish smell.” It wasn’t until middle age that I discovered that I actually rather liked the fresh clean taste of sushi. I got in trouble once when I shared a spontaneous insight with students that a “disgust” response to male homosexuality might be tied to the very thought of anal sexuality, despite a gay friend telling me there were books available to gay men for overcoming revulsion to certain smells. Empirical research recently showed that disgust sensitivity predicts intuitive disapproval of gays. Let’s just not talk about it.