By Joshua Lehr, Certified GNM Clinician
“Ewww… that’s disgusting!” Can you imagine the face that goes with that statement? That facial expression is a common reaction to the feeling of disgust. It is an example that can be used to prove that symbolic thinking is equivalent to literal thinking in the brain. This, in turn, explains why an unexpected shock to the psyche leads to an adaptation in the body. How?
The literal sense involved with disgust is primarily an offensive taste, or a foul odor. Of course both are related since smell is mainly what we use to perceive flavor. The bad taste or smell indicates that there is something wrong, and possibly dangerous, with what’s in the food or air. To protect ourselves from the danger the instinctive response is to scrunch the nose, exhale, spit out, and in extreme cases retch. This reaction is especially evident in infants while trying new foods. In his book The Expression of the Emotions in Man and Animals, Charles Darwin examines the physical response to disgust as described above. Then he goes on to give examples of how just the mere thought of something that tastes disgusting can induce the same reaction. Of course this is all literal thinking.
Next, Darwin writes about things that are symbolically revolting. In order to understand the figurative expression of it, consider the following phrases: “You disgust me!” and “I spit on your grave!” This section of his book provides examples of these kinds of moral (symbolic) disgust from various cultures. He cites how instinctive behavior is exhibited in all cases. People use the same facial expressions to show it, spitting and sniffing out. What can we discern from this? An important point. Symbolic and literal thought is, in some brain networks, processed identically.
So then, in what ways does disgust affect the body? The physical symptoms of disgust can include nausea, dizziness, sweating, vomiting, and fainting. These symptoms are the key to understanding the adaptation process. Why? Because they happen to be the same as in the condition hypoglycemia, also called low blood sugar. So they both have the same symptoms, what does that prove? Before we answer that we first need to briefly review how blood sugar is regulated in the body.
Blood sugar is controlled through two types of islet cells in the pancreas. They produce the hormones glucagon and insulin. Glucagon stimulates the production of glucose (sugar). Insulin promotes the absorption of it. This cycle normally maintains a balance. However an imbalance of low glucagon results in low blood sugar and low insulin results in diabetes.
So, now, let’s put the pieces together. Hypoglycemia is often associated with diabetes. Several studies have shown a link between olfactory function and diabetes. One concludes, “…olfactory dysfunction seems to play a significant role in food intake and energy balance, interacting with endocrine system and glucose metabolism.” Glucose metabolism is what the islet cells are all about. So the sense of smell has been linked to blood sugar regulation. By what is disgust primarily triggered? Smell. However, not just the foul odor, but the fear of being soiled, or poisoned by it. And, as we saw above, this can be either literal or symbolic.
So, is it a coincidence that the symptoms of hypoglycemia and disgust are the same? No. In fact, the reason for this is that a shocking, unexpected experience of disgust triggers a hardwired survival program that causes hypoglycemia. It shuts down the islet cells that make glucagon. In turn this lowers our blood sugar and we get protective yet unpleasant symptoms.
It makes biological sense because then we will ‘faint away’ from the danger. This point is reinforced with the behaviors involved with revulsion like turning away, withdrawal, and avoidance. Also, as it turns out, a small area in the center of the brain called the diencephalon registers both shocks that affect blood sugar and smell. Furthermore, as a protective mechanism, the brain stores what we were sensing at the time of a shock to the psyche. So repeated subconscious reminders of that disgust retrigger the instinct and the hypoglycemia.
Therefore, what can we conclude? Whether it is literal or symbolic thinking, our instinct responds to shocking disgust. It adapts our body in the best possible way to physically handle the situation – avoiding a perceived danger. So, the next time you say, “Ewww,” remember that this is an intrinsic protective function. It is a Special Biological Program. One of many that demonstrate how symbolic thinking adapts the body.