Nose-picking primates are helping scientists understand the evolution and possible functional role of behavior in humans.
For the first time, researchers recorded aye-aye – a long-fingered lemur – inserting the longest finger into its nostrils and then licking it.
So far, 12 other primate species, including humans, have been documented poking their noses and eating mucus.
Scientists said their findings, published in the Journal of Zoology, could shed light on how this behavior evolved and whether it plays a functional role.
Lead author Anne-Claire Fabre, scientific associate at the Natural History Museum in London, said: “There is very little evidence as to why we and other animals take our noses off.
“Almost all the documents you can find were written as a joke. Of the serious studies, there are some in the field of psychology, but for biology there is almost nothing.
“One study shows that removing the nose can spread bacteria such as staph, while another shows that people who eat their own snot have less tooth decay.”
The aye-aye, the largest nocturnal primate in the world, belongs to a category of species known as strepsyrrhine primates and is native to Madagascar.
It has rodent-like teeth and a specialized long, thin middle finger.
The fingers of the aye-aye are used to locate food within the wood by tapping it and then extracting small larvae. The researchers also noted that the lemur uses its longest finger to pinch its nose.
Mrs. Fabre said: “It was impossible not to notice this yes yes you bite your nose.
“This wasn’t just a one-off behavior, but something he was completely involved in, inserting his extremely long finger up a surprisingly long distance into his nose and then sampling whatever he dug by licking his finger to clean it!”
The researchers used a CT scan to look inside the skull and hand of a specimen at the museum and found that the finger could reach up to the throat.
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Previous scientific research has suggested that there may be health benefits to eating snot, but researchers believe that in this case there is a possibility that the animal ingesting its own mucus may simply be due to its texture, crunchiness and saltiness.
Roberto Portela Miguez, Senior Curator of the Natural History Museum and co-author of the article, said: “It is fantastic to see how museum specimens and digital methods can help us clarify behaviors that are generally rather difficult to observe in their natural habitat.
“We hope future studies build on this work and help us understand why we and our closest relatives insist on combing our noses.”