Why do all people have the same aversion to some things? How did such an unpleasant feeling help to survive and why is it so important for each of us? Evolutionary psychologist Glenn Geher provides some disgusting but very compelling examples in his defense.
Nobody likes ticks. No one wants to be in a dog walking area, especially if their owners don’t clean up after their pets. Seeing how another turns out, many experience nausea, even if before that they felt great.
For anyone who is still not convinced that evolution has anything to do with today’s psychology and behavior, these examples are irrefutable evidence that aversion to certain stimuli is universal to all members of humanity.
New York University professor Glen Geher is convinced that behavior and habits are explained precisely by evolutionary processes. “Ask any man if he likes ticks, excrement, and the like, and he will be horrified. Women in early pregnancy are especially sensitive to such stimuli.”
Research has shown that even those who doubt that evolution has affected our psyches today are convinced that our general aversion to unpleasant stimuli is built into the evolutionary history of mankind.
Behavioral Immune System
Evolutionary psychologists believe that disgust in response to unpleasant stimuli is caused in us by the «behavioral immune system.» It is very similar to the physiological immune system, and its purpose is to keep pathogens out of the body in order to keep it healthy.
To understand the logic of the process, one can try to imagine that one of our distant ancestors could be attracted by the smell of vomit or excrement and would specifically seek to meet them. But they are full of bacteria that can cause many diseases! From the point of view of evolutionary psychology, such behavior would be, to put it mildly, not very adaptive. Such preferences would lead to adverse health outcomes, and on an evolutionary scale, any genes encoding this behavior would die a Darwinian death.
We are the result of a selection over thousands of thousands of generations, which usually leads to the right results. In other words, ancestors who had an aversion to parasites, larvae, and vomit had a better chance of surviving—and therefore of procreating, giving us, today’s humans, a chance to appear in this world.
And this is partly due to the health benefits that the behavioral immune system brings. And that, in turn, is produced by stimuli that are potentially full of pathogens and other substances that could kill us.
Conclusions
“So the next time you find that moldy cheese left in the back of the fridge or vomit on the sidewalk at the bar is disgusting, you can take some comfort in the knowledge that you are not alone. The stimuli that cause this response usually hit the same nerve in people all over the world,” writes Professor Geher.
This is our reaction, the work of the behavioral immune system is a fundamental part of the evolutionary heritage and one of the basic adaptations that made it possible for us to live on the planet. In a word, disgust is an evolutionarily adaptive and very useful feeling.
About the Author: Glen Geher is a New York University professor of evolutionary psychology.