Aye ayes: animal picks nose with extremely long finger, why lemurs do it - is picking your nose good for you?

Although humans usually frown on nose picking and snot eating, scientists have discovered that one primate species has specialised fingers for doing just that.

For the first time, researchers captured the aye-aye, a long-fingered lemur, inserting its unusually long digit into its nostrils and then licking its finger clean.

Here is everything you need to know about it.

What is an aye-aye?

The aye-aye is a species of primate native to Madagascar that belongs to the strepsirrhine family. The lemur, which is also known as the world's largest nocturnal primate, possesses rodent-like teeth and a specialised long and thin middle finger.

The aye-aye’s fingers account for around 65% of the length of the creature's hand, which it utilises to locate food inside wood by tapping on it and then extracting small grubs.

But researchers discovered something unusual about the aye-aye: the lemur picks its nose with its longest finger.

Why does it pick its nose?

Previous scientific research has suggested that eating snot may have health benefits, but the researchers feel that in this situation, the animal digesting its own mucus may simply be due to its texture, crunchiness and saltiness.

The scientists said their findings, published in the Journal of Zoology, could shed some light on the evolution and the possible functional role of nose picking across all these species.

Lead author Anne-Claire Fabre, a scientific associate at the Natural History Museum in London, said: “There is very little evidence about why we, and other animals, pick our nose.

“Nearly all the papers that you can find were written as jokes. Of the serious studies, there are a few in the field of psychology, but for biology there’s hardly anything.

“One study shows that picking your nose can spread bacteria such as Staphylococcus, while another shows that people who eat their own snot have fewer dental cavities.”

So far 12 other primate species, including humans, have been documented picking their nose and eating the mucus.

Where does its finger go?

To further understand the behaviour, researchers employed CT scans, commonly used by medical professionals to gather internal images of the body, to examine the skull and hand of an aye-aye specimen in a museum.

Their aim was to reconstruct the position of the middle finger inside the nasal cavity. Findings suggested that the finger is likely to descend all the way into the throat.

Fabre said: “This was not just a one-off behaviour but something that it was fully engaged in, inserting its extremely long finger a surprisingly long way down its nose and then sampling whatever it dug up by licking its finger clean!”

Roberto Portela Miguez, senior curator in charge, Mammals at the Museum, and a co-author on the new paper said: “We hope that future studies will build on this work and help us understand why we and our closest relatives insist on picking our noses!”