Image of four kids picking their noses

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Making Predictions

Why Do Little Kids Eat Their Boogers?

BEFORE YOU READ: Think about the role snot plays in the body.

Everyone’s probably seen a little kid shove a finger up their nose, fish out a booger, and pop the congealed snot into their mouth. But is there a scientific reason behind this habit?

Maybe . . . and maybe not, says Anne-Claire Fabre. She’s an evolutionary biologist at the Natural History Museum of Bern in Switzerland. She studies how animals develop traits over time. In 2022, Fabre saw an aye-aye at a research center nibbling its boogers—just like a human kid. Aye-ayes are small primates, a group that includes monkeys, apes, and people.

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COMMON HABIT: Gorillas are one of the many animals that pick their noses

Fabre and her team searched scientific papers for mentions of other primates that engaged in mucophagy, or consuming boogers. They found 12 other species—including chimpanzees, macaques, and gorillas—that had been caught in the act. Since the behavior is so common, the scientists wondered if there could be some benefit to eating boogers.

“Mucus acts like a shield that protects the thin skin and blood vessels in the nostrils,” says Fabre. The sticky stuff also catches dust and pollen that can trigger allergies, as well as harmful pathogens, like bacteria and viruses. Some research hints that eating boogers full of grime and germs might boost the body’s disease-fighting immune system. But other research shows that nose picking can spread pathogens and make you sick. For now, it’s still a scientific mystery why many animals snack on their snot. “It might just be for its taste and crunchiness,” says Fabre.

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