The emotion of disgust may be unpleasant, but scientists think it has a real practical purpose in protecting us from harm.

In a slew of new books and research papers, the evolution of disgust and its role in attitudes toward food, sexuality and other people is being carefully explored.

Valerie Curtis, a self-described “disgustologist” from the London School of Hygiene and Tropical Medicine, says the emotion is “incredibly important.”

Speaking last week from a conference on disgust in Germany, she said, “It’s in our everyday life. It determines our hygiene behaviors. It determines how close we get to people. It determines who we’re going to kiss, who we’re going to mate with, who we’re going to sit next to. It determines the people that we shun, and that is something that we do a lot of.”

And it starts early. “Kids in the playground accuse other kids of having cooties,” she says. “It works, and people feel shame when disgust is turned on them.”

Disgust can even sway our political views as adults — some studies have suggested that conservatives are more prone to disgust than liberals are. And it’s clear that what people find disgusting, they usually find immoral, too.

The research on disgust may also have practical benefits, including providing clues to obsessive compulsive behaviors. For example, some describe excessive hand washing as “disgust gone wild.”

Daniel Fessler, an anthropologist at the Center for Behavior, Evolution and Culture at the University of California, Los Angeles, said the fact that pregnant women are often more sensitive to disgust is linked to an increase in progesterone levels. And since this effect is especially true in the first trimester of pregnancy, when derailing fetal development would have the most dire effects, it could actually protect the fetus from harm.

“It is becoming a model emotion,” said Jonathan Haidt of the University of Virginia.

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