With its large eyes, bushy tail, and sensitive ears, the aye-aye can seem like a cute, albeit quirky, creature. But now researchers have found he has a less endearing trait: he uses his long middle finger to pick his nose – and eat the mucus.
Aye-ayes are – like humans – primates, but they are nocturnal, endangered and found only in Madagascar. The object of superstition, they have a number of unusual features, including rodent-like teeth and a skinny, elongated finger with a ball joint.
Although the animal is known to use its phenomenal finger to tap on hollow wood to locate larvae and fish them out, researchers revealed they have video footage showing it being used for another purpose, rather banal: picking your nose.
“In doing so, this animal inserts the full length of its extra-long, skinny, highly mobile middle finger into the nasal passages and then licks the collected nasal mucus,” the authors wrote in the journal Zoology.
Dr Anne-Claire Fabre, an assistant professor at the University of Bern who co-authored the research, said she recorded the behavior on video in 2015 while observing captive aye-ayes at the Duke lemur centre.
“I was really surprised,” Fabre said, adding that the entire middle finger had disappeared from the creature’s nose. “It’s almost 8cm – it’s really long, and I was wondering where that finger was going.”
To dig deeper, the researchers created a 3D model using CT scans of the aye-aye’s head and hand to figure out where the middle finger went. The results suggested that the digit extended deep into the head.
“That finger basically ends in the throat,” Fabre said, adding that even though nose tingling hadn’t been seen in aye-ayes in the wild, that didn’t mean it hadn’t happened. product.
The team said the aye-aye is in good company when it comes to nose picking, revealing the trait has been recorded in at least 11 other primate species, including humans, capuchins, macaques, chimpanzees and orangutans, with some species also using tools to get the job done. The researchers said nose picking appeared to be most common in species with fine manipulation skills.
It’s unclear why aye-ayes, or other species, have a penchant for nose-picking, with researchers noting that it could simply be an act of “self-cleaning.” But, they added, the fact that multiple species ate the mucus suggested there may be other explanations.
Among them, the team noted, were studies that suggested the “texture, crunch and salty taste” of the material might be appealing, that eating snot can prevent bacteria from sticking to teeth, and that the trait could stimulate immune responses. However, there could be a downside, they said: Other research has suggested that nose picking spreads nasal bacteria.
Fabre added that nose picking was understudied and more research was needed. “You never know when you’re studying this type of behavior where you might end up, and sometimes you might find an application that you didn’t expect,” she said.