These lemurs take nose-picking to a new level

Aye-ayes’ ultralong middle fingers may reach back through their nose to their throats

An award-winning comic series from Science News Explores

JoAnna Wendel

Nocturnal lemurs called aye-ayes are true champions of nose-picking.

A new video offers the first evidence that these primates stick their fingers up their snouts and lick off the snot. They don’t use just any finger for the job, either. Aye-ayes mine for mucus with the super-long middle finger they normally use to pluck tasty grubs from tree bark. CT scans of the inside of an aye-aye’s head suggest that this spindly digit can poke all the way through the animal’s nasal passages to reach its throat.

“I was really surprised,” says Anne-Claire Fabre. She’s a biologist at the National History Museum of Bern in Switzerland who captured the video. Fabre filmed a female aye-aye named Kali picking her nose at the Duke Lemur Center in Durham, N.C. An aye-aye is about as big as a house cat. But its clawed middle finger is some eight centimeters (more than three inches) long. Kali was shoving almost the entire digit up her nose.

This got Fabre and her colleagues curious. How many other primate species have been caught with their fingers in their nostrils? A search of past studies and online videos revealed that 11 other species of primates are known to pick their noses and snack on the snot. The team shared those findings online October 26 in Journal of Zoology.

Panel 1. Image: A brownish-gray, four-legged, furry animal with large ears holds onto a tree branch while picking its nose with one of its long fingers. This animal, called an aye-aye, is looking at the ‘camera’ and saying, “What?” Text: aye-ayes take nose-picking to the extreme, Written by Maria Temming, Illustrated by JoAnna Wendel
Panel 2. Text (above image): You might find it gross when someone picks their nose (even if you do it yourself). Image: A Black girl and a white girl are sitting at side-by-side desks. The white girl is picking her nose, while the Black girl sticks out her tongue and says, “Gross!” Text (below image): But human nose-pickers have nothing on aye-ayes.
Panel 3. Text (above image): These weird nocturnal lemurs are native to Madagascar, an island off the coast of Africa. Besides looking a bit bizarre, aye-ayes are known for their super-long middle fingers. They use those fingers to fish tasty grubs from tree bark. Image: A map shows Africa, Europe and the Middle East, with the island of Madagascar just off the eastern coast of Africa. An inset pointing to Madagascar shows an aye-aye in a tree saying, “Hook, line and finger!”
Panel 4. Text (above image): Biologist Anne-Claire Fabre was studying these primates at the Duke Lemur Center in Durham, N.C. One night, she caught an aye-aye doing something unexpected. Image: A brunette white woman holding a video camera is watching an aye-aye standing on a waist-heigh platform and picking its nose. Fake trees stand in the background of the room. The woman is sticking out her tongue and saying, “What the heck is going on??” while the aye-aye thinks, “It’s like a snot lollipop!” Text (below image): Fabre filmed the lemur sticking its long middle finger up its nostril, then licking off the snot.
Panel 5. Text (above image): “I was wondering where the finger was going,” says Fabre, who works at the Natural History Museum of Bern in Switzerland. By looking at CT scans of an aye-aye’s head, her team found that the animal’s 8-centimeter-long finger may poke all the way back to its throat. Image: The brunette woman from the previous panel, Anne-Claire Fabre, points a stick at a diagram of the inside of an aye-aye’s head, which shows how an aye-aye’s finger could travel through its nasal passages down to its throat. Fabre is saying, “Talk about digging deep!”
Panel 6. Text (above image): Aye-ayes and humans are not the only nose-pickers in the primate family tree, it turns out. Fabre’s team used past studies and online videos to confirm that aye-ayes are the 12th primate species known to pick their noses and snack on the snot. Image: An aye-aye, a baboon, a capuchin monkey and a white boy wearing a red shirt and jeans all sit on different branches of a tree, all picking their noses. Text (below image): Nose-picking species tend to have nimble hands and use tools.
Panel 7. Text (above image): Since so many primates pick their noses and eat the boogers, researchers wonder… Image: Fabre sits slumped over her desk, clutching her head, as she looks through a book. A stack of books, several crumpled papers and two coffee mugs also sit on the desk, which is inside an office. Fabre thinks, “Self-grooming? Boosting immune system? Shock value???” Text (below image): …could this nasty habit have some hidden benefit?
Panel 8. Text (above image): Finding out will require a more complete census of what species mine and munch on their own mucus. Image: A man and a woman stand in a forest. The man is looking at a monkey in a tree with binoculars, while the woman points at it and smiles. Another monkey sits higher up in the tree. Text (below image): That could mean researchers spending more time in the field watching animals—or perhaps you paying more attention on that next trip to the zoo.
All: JoAnna Wendell

Maria Temming is the assistant editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing.

JoAnna Wendel is a freelance science writer and cartoonist in Portland, Ore. She loves to make comics about all types of science, but she especially loves drawing planets, invertebrates and sea creatures. When she's not drawing, JoAnna is probably reading, hiking or hanging out with her cat, Pancake.