The Evolutionary Biology of Disgust, Part I
How can a rational emotion be hijacked for political purposes? The answer holds the key to much human misery . . .
In a forthcoming book, Martha Nussbaum describes the Politics of Disgust that has frequently dominated American discourse over homosexuality. She reminds us that its roots run deep in human history, providing historical depictions of Jews and Untouchables in India as filthy, disease-ridden, and necrotic. She has no problem finding current examples in American politics to support the notion that anti-gay sentiment (but not anti-lesbian sentiment) is driven by the same strategy of rendering homosexual acts, real and imagined, as disgusting and unnatural. For practical reasons, however, she cannot spend too much time examining the rational basis for disgust as an emotion and its stunning amenability to being hijacked.
Evolutionary biology would suggest that disgust should be a rational emotion. The vast majority of humans probably feel disgust at the thought of incest or eating feces or handling a rotting corpse. How come? Quite probably because of natural selection. Cave people with an aversion to incest developed a stronger and more diverse gene pool; those who stayed away from feces and rotting corpses probably lived longer and therefore had more children. This is disgust as an emotion in the service of humanity. Critically, it explains why we don’t automatically reject disgust as an illegitimate emotion when we feel it. In fact, we are probably more likely to accept it in ourselves than anger, which we suspect usually evidences a problematic loss of self-control. We curse ourselves for losing our tempers, but we seldom say, “I shouldn’t have been disgusted by that.”
This evolutionary salience creates tremendous opportunities for exploitation. A crude political strategy therefore is to accuse someone of routinely doing something disgusting. Our disgust at the act gets transferred to the person or group with predictably horrific results. Nussbaum describes pamphlets accusing gay men of drinking blood and eating feces. This story is far too simple, however. First of all, it does not explain the motivation of the original accuser. Why conceive of the discriminatory strategy in the first place—from whence comes the original disgust? Second, it doesn’t explain why people who don’t read or believe the lurid pamphlets seem nonetheless disgusted by homosexuality.
I’ll reject one possible theory immediately: disgust with homosexuality itself is evolutionary, e.g. our primitive ancestors who avoided certain sex acts thrived as compared to those who did not. First, natural selection does a poor job of explaining the significant percentage of the current population who are gay or lesbian. Shouldn’t disgust have helped select out the trait? Second, as Martha points out in her book, present feelings of disgust aimed at homosexuals are quite a-historical. There’s no evidence that mankind has felt this way over the millennia . . . can we work out a more complex story?