Picking noses and eating snot can be frowned upon by humans, scientists have found, but one particular type of primate species has specialized fingers to do just that.
Researchers have, for the first time, recorded the aye-aye – a long-toed lemur – inserting its extremely long finger into its nostrils and then licking its finger clean.
So far, 12 other primate species, including humans, have been documented picking their noses and eating the mucus.
The scientists said their findings, published in the Journal of Zoology, could shed light on the evolution and possible functional role of nose picking in all of these species.
Lead author Anne-Claire Fabre, a science associate at the Natural History Museum in London, said: ‘There is very little evidence as to why we, and other animals, choose noses.
“Almost every article you can find was written as a joke.
“Among the serious studies, there are some in the field of psychology, but for biology, there is almost nothing.
“One study shows picking your nose can spread bacteria such as Staphylococcus, while another shows people who eat their own snot have less tooth decay.”
The aye-aye belongs to a category of species called strepsirrhine primates and is native to Madagascar.
Also known as the world’s largest nocturnal primate, this lemur has rodent-like teeth and a specialized long, slender middle finger.
The aye-aye’s fingers are about 65% of the length of the hand – which the creature uses to locate food inside the wood by tapping on it and then extracting small larvae.
But the researchers also observed something else about the aye-aye: the lemur uses its longest finger to pick its nose.
Ms Fabre said: “It was impossible not to notice this aye-aye picking his nose.
“It wasn’t just a one-off behavior, but something he was fully engaged in, inserting his extremely long finger in a surprisingly long way into his nose, then sampling everything he dug up as he licked his finger for it. to clean !”
To better understand this behavior, the research team used an imaging technique known as computed tomography – typically used by medical professionals to obtain internal images of the body – to look inside the skull and of the hand of an aye-aye specimen in the museum.
Their goal was to reconstruct the position of the middle finger inside the nasal cavity.
The results suggest that the finger is likely to descend into the throat.
Previous scientific research has suggested that there may be health benefits to eating snot, but researchers believe that in this case it’s possible that the animal ingesting its own mucus is simply due to its texture, its crunchiness and salinity.
Roberto Portela Miguez, Senior Curator-in-Charge, Mammals at the Museum, and co-author of the new paper, said, “It’s great to see how museum specimens and digital methods can help us elucidate behaviors that are generally quite difficult to observe in their natural habitat.
“We hope that future studies will build on this work and help us understand why we and our close relatives insist on picking our noses!”