Researchers find why aye-ayes shove their longer middle finger up their brains

The scientists created a 3D model using CT scans of the animal to discover that the digit extended deep into the head.
Loukia Papadopoulos
Aye-ayes pick their noses.jpg
Aye-ayes are largely found in Madagascar.


The cute adorable aye-ayes found in Madagascar have been revealed to have some quite disturbing traits, according to new research published in the journal of Zoology and reported by The Guardian on Thursday.

A very long middle finger

The animals' have a very long middle finger that is used for tapping on hollow wood to locate grubs and fish them out. However, now, researchers have produced video footage of the same finger being used for nose picking.

The researchers further note in their study that once the animal picks its nose, it follows up by licking the nasal mucus collected.

Dr. Anne-Claire Fabre, an assistant professor at the University of Berne and a scientific associate of London's Natural History Museum who co-authored the research, told The Guardian she first was "really surprised" by the strange behavior she recorded in 2015 while observing captive aye-ayes at the Duke lemur center.

She further explained that the whole middle finger disappeared up the creature's nose. "It is nearly 8cm – it is really long, and I was wondering where this finger is going," she said.

Researchers find why aye-ayes shove their longer middle finger up their brains
An aye-aye in the wild.

A 3D model to better understand the behavior

To answer this question, the researchers created a 3D model using CT scans of the head and hand of the aye-aye and discovered that the digit extended deep into the head.

"This finger is basically ending in the throat," said Fabre. However, the unusual activity has yet to be observed in aye-ayes in the wild. Fabre stated that that does not mean it does not occur.

Nose-picking is quite common in species with fine manipulative skills. In the past, it has been recorded in at least 11 other primate species, including humans, capuchins, macaques, chimpanzees, and orangutans. Some species go as far as using tools to do the job.

The researchers speculate that the activity could be an act of "self-cleaning." However, the fact that several species ate the mucus may lead to other explanations.

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Fabre added that more research was needed to truly understand this behavior. "You never know when studying this type of behavior where you can end up, and sometimes you can discover an application that we're not expecting," she said.

At the moment, she speculates that the "texture, crunchiness, and saltiness" of mucus could be appealing to the ayes-ayes, that the activity may prevent bacteria from sticking to teeth or that it could boost immune responses. However, these are still all theories until they can be proven.

Fabre warned of one danger: other research has suggested nose-picking spreads nasal bacteria. Studies have even found that in mice models, the activity can lead to Alzheimer's or dementia because bacteria can travel through the olfactory nerve in the nose and into the brain.

Could the same principles apply to ayes-ayes, or are they biologically predisposed to avoid such risks?

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