“It’s something that’s crunchy and a little salty.” Could there be something more than just a bad habit behind this behavior, or do they do it simply because they like it?
We’ve all seen it: a child with a finger stuck in his nostril, exploring the cavity looking for a nugget of gold, removing it and then swallow it as if it were a tasty snack.
Could it be disgusting to adultsbut most children seem completely unfazed. So why do children eat their “monkeys” — and do they? know something?
Most parents will tell you how common it is for children to eat their own mucus, a behavior known as “mucofagia“, but data on its prevalence are scarce.
One from 1995 suggests that picking your nose isn’t limited to children; you adults do it too usually. Another, in 2001, based on a survey of 200 teenagers in India, concluded that almost all participants they admitted picking their nose; nine of the participants said they did so routinely.
There are still no rigorous studies on why children eat their own mucus. However, researchers have discovered that mucophagia is shared by at least 12 other primate species.
The evolutionary biologist Anne-Claire Fabre He discovered this for the first time when he was observing the aye-aye (Daubentonia madagascariensis). This species of lemur is known for its 8 centimeter middle finger long, which he uses to remove insects from difficult-to-reach crevices.
In 2015, when Fabre was observing an aye-aye in captivity, she was surprised to see it sticking that long, thin finger into its nostrils, extracting mucus, and then .
“It was hilarious and disgusting at the same time“, recalled Fabre, professor at the University of Bern, Switzerland. “It seemed like I was really enjoying what I was doing. It’s something they do quite often.”
Fabre wondered if other primates also eat its mucus, and conducted a literature review that included his own aye-aye observations, in which he found evidence that gorillas, bonobos, chimpanzees, monkeyscapuchins and other primates also pick their noses and eat the mucus.
Most species use their fingers, but some use sticks to extract mucus. Some primates even returned the favor, picking each other’s nosesthe investigation revealed.
“When analyzing the composition of mucus, It’s mostly watermore than 98%”, says Fabre. The remainder is made up of an iprotein and glucose ingredient called mucinsI know.
It is possible that the animals have any benefit when consuming these ingredients, in the same way as some species eat their own feces to digest the nutrients that still remain there, explained Fabre.
This idea raises the question of whether there could be a evolutionary basis more profound for mucophagy in humans.
The mucus creates a protective layer that retains dust, spores and microorganisms disease-causing when we inhale, before they reach the lungs.
In 2013, a biochemist shared the hypothesis that eating mucus could expose children to small doses of pathogens which train the immune system to identify these molecules and help trigger an immune response. However, this idea never been tested through empirical investigation.
Chittaranjan Andradeprofessor at the National Institute of Mental Health and Neurosciences in Bangalore, India, and author of the 2001 study on the habit of picking noses in teenagers, is cautious about these theories.
“I’m skeptical. Any immune substance that survives drying in the mucus is likely to be very reduced in quantityand will also probably be digested after ingestion”, Andrade explained to .
Experts warn that as nasal mucus can propagate bacteria causes of pneumoniathe habit of picking their nose and mucophagia in children must be controlled when they are around immunocompromised people.
No evidence to support the idea that mucophagy strengthens immunity, researchers sought more intuitive reasons to explain why children eat their own mucus.
Snots can create itching, tightness and discomfort in the nosewhich takes children to “clean the salon” — and the more curious ones can then try the flavor, Fabre suspects.
In one published in 2009, a researcher asked children directly why did they eat the snot. The results were not peer-reviewed and were based on a very small sample of just 10 children, but their responses included the fact that they liked eating “monkeys” simply because of their appealing texture and flavor.
Andrade believes that children develop this habit because they do not yet have the negative connotation it has for older people.
Until there is concrete research into the issue, the exact answer to why children eat mucus will remain unclear. For Fabre, at least, it is a topic that deserves further investigation, to understand if there are possible benefits or harms of mucophagia for child development.
In the end, the researcher believes what the children say and thinks they can eat the snot simply because they like.
“It’s something that’s crunchy and a little salty“, he says. And after having watched aye-aye picking their nose for hours and learning about the prevalence of this habit in other species, Fabre no longer finds it repugnant: “Honestly, in my opinion, It’s not something that’s disgusting“.
