The aye-aye (Daubentonia madagascariensis) is a species of strepsirrhine primate closely related to lemurs and the largest nocturnal primate in the world.
The aye-aye (Daubentonia madagascariensis). Image credit: David Harin / Duke Lemur Center.
The aye-aye is one of the most unusual and fascinating creatures on Earth famed for its large eyes and big ears.
The animal is a type of lemur that is found only on the island of Madagascar.
The third and fourth fingers of the aye-aye are elongated and skinny and are highly specialized to help them feed.
Amazingly the fingers make up about 65% of the length of the hand with the hand itself making up over 40% of the total length of the forelimb.
The aye-aye uses these adaptations to find food by tapping on wood, generating acoustic reverberations, which allow the animal to locate grubs inside which it can then extract with the specialized digits.
“It was impossible not to notice this aye-aye picking its nose,” said Dr. Anne-Claire Fabre, curator of mammals at the Naturhistorisches Museum der Burgergemeinde Bern and a researcher at the University of Bern, as well as a researcher at the Natural History Museum in London.
“This was not just a one-off behavior 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.”
Dr. Fabre noticed the use of the aye-aye’s long middle finger when filming their behavior at the Duke Lemur Center.
“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.”
In their research, Dr. Fabre and colleagues analyzed previous studies that covered nose-picking in primates.
They found that this behavior has been documented in at least 12 primate species including humans, chimpanzees and orangutans.
They also captured photographic and video evidence of the behavior in aye-ayes.
Additionally, they CT-scanned the skull and hand of an aye-aye specimen to reconstruct the position of the middle finger inside the nasal cavity.
These reconstructions suggested that the finger is likely to descend all the way into the throat.
“Aye-ayes are highly endangered, and really need our help,” said Dr. Roberto Portela Miguez, senior curator in charge at the Natural History Museum in London.
“Papers like this can hopefully help draw attention to the species, highlight how little we may know about them and get more people to support their conservation.”
The paper appears in the Journal of Zoology.
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A.-C. Fabre et al. A review of nose picking in primates with new evidence of its occurrence in Daubentonia madagascariensis. Journal of Zoology, published online October 26, 2022; doi: 10.1111/jzo.13034
