The Curious Habit of Kids Eating Boogers

We’ve all noticed it: a child, often with one finger exploring a nostril, pulling out a treasure and, well, eating it. While it might turn the stomachs of adults, kids don’t seem to mind at all. But why do they do it? And could there be some hidden benefits?

Many parents would agree that it’s pretty common for kids to munch on their own mucus, a behavior known as “mucophagy.” Still, there’s not much data available about how widespread this is.

Interestingly, a survey indicates that nose-picking isn’t just a child’s pastime; adults engage in it, too. A study from 2001 involving 200 teenagers in India found that nearly all admitted to picking their noses, with nine of them saying they often ate the boogers. However, there’s been little dedicated research into why kids actually eat their mucus.

On the flip side, researchers have discovered that mucophagy isn’t unique to humans; at least 12 other primate species partake in it, too.

Evolutionary biologist Anne-Claire Fabre made this discovery while observing an aye-aye lemur known for its long middle finger used to extract insects. During her observations in 2015, she was taken aback to see this lemur digging into its nostrils, catching mucus, and then licking its finger.

“It was both hilarious and gross,” Fabre recalled, an associate professor at the University of Bern. “It looked like it was genuinely enjoying it. They do this often.” While we can’t say for certain that all aye-ayes share this habit, Fabre suspects it’s likely common among them.

This observation prompted Fabre to investigate whether other primates also eat their mucus. Through a literature review, which included her observations, she found that gorillas, bonobos, chimpanzees, and several other primates not only pick their noses but also partake in a bit of eating. While many use their fingers, some even get creative with sticks. Interestingly, some primates will also pick the noses of their peers.

Fabre pointed out that mucus is primarily water, making up over 98%. The rest consists mostly of mucins and salts. It’s possible that consuming these could offer some benefits, akin to how some animals consume their feces for additional nutrients.

This raises intriguing questions about whether there’s an evolutionary basis for humans to indulge in mucophagy.

Mucus plays a crucial role in trapping harmful particles and microbes as we breathe. A 2013 study by a biochemist suggested that if children eat their boogers, they might receive tiny doses of pathogens, which could train their immune systems to respond more effectively. However, this idea hasn’t been officially tested.

Dr. Chittaranjan Andrade, who conducted a study in 2001, expressed skepticism regarding this immunity theory. He noted that any immunological substances in mucus are likely insignificant in quantity and unlikely to survive digestion.

Others warn that nasal mucus can transport harmful bacteria, suggesting mucophagy should be monitored, especially around those with weakened immune systems.

With no solid evidence supporting immunity benefits, researchers are now exploring simpler explanations for why kids indulge in this habit. It could be the irritation and discomfort boogers cause that leads children to pick their noses and, perhaps out of curiosity, taste what they find.

One researcher asked kids directly about their booger-eating habits, yielding insights published in a non-peer-reviewed book chapter. Among ten kids, they reported enjoying the texture and taste.

Andrade believes that kids engage in this behavior simply because it hasn’t yet picked up the negative stigma it has in later years. “They often do it publicly and, when noticed, they get scolded. It seems this stigma influences whether they repeat it, but mostly not in public,” he suggested.

Until more concrete studies emerge, the reasons behind children’s mucus-eating habits remain somewhat unclear. To Fabre, however, it’s a conversation worth having, looking deeper into any potential benefits or downsides of this behavior.

Ultimately, she believes kids might simply enjoy eating their boogers. “It’s crunchy and a bit salty,” she remarks. Having spent hours observing aye-ayes and learned about this habit across species, she doesn’t view it as disgusting anymore: “Honestly, I think it’s not that gross.”