The extra-long middle fingers of the animals most likely reach all the way to the back of the throat.
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| Under ideal conditions, aye-ayes aren't the most photogenic of creatures. But, caught in the dead of night, hunched over with a finger several centimeters up its nose, this strange primate appears positively haunting. FABRE, A.-C. |
Aye-ayes are undisputed nose-pickers.
A new video shows these nocturnal lemurs of Madagascar sticking their fingers up their noses and licking the mucus away. They also don't use just any finger for the job. The primates spelunk for snot with their ultralong, witchy middle fingers, which they normally use to find and fish grubs out of tree bark.
"This is a brilliant example of how science can serve human curiosity," says Michael Haslam, a London-based primate archaeologist who was not involved in the new research. "My initial reaction was that it's a cool — and slightly creepy — video, but [the researchers] have gone beyond that initial reaction of 'What on Earth? 'to actually investigate what's going on inside the animal."
Kali, a female aye-aye (Daubentonia madagascariensis) at the Duke Lemur Center in Durham, N.C., stars in the new footage. "I was really surprised when the aye-aye stopped eating and started picking its nose," says evolutionary biologist Anne-Claire Fabre, who filmed the video. "I was wondering where the finger was going." An aye-aye is roughly the size of a house cat, but its clawed middle finger is approximately 8 centimeters long. And Kali was daintily licking her own snot with almost the entire digit up her snout.
"There was one moment where the camera was [shaking], and I was giggling," says Fabre of Switzerland's Natural History Museum. She then asked her coworkers if they had ever seen an aye-aye pick its nose. "Those who worked a lot with aye-ayes would tell me, 'Oh, yeah, it happens a lot,'" says Fabre, who later witnessed the behavior in several other aye-ayes.
According to a CT scan reconstruction of the inside of an aye-head, aye's this spindly digit probably pokes all the way through the animal's nasal passages to reach its throat, researchers report online on October 26 in the Journal of Zoology.
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| Based on CT scans, a reconstruction of the internal structure of an aye-head aye's reveals that when the primate picks its nose, the tip of the long middle digit likely reaches the back of the throat. LEFT TO RIGHT: RENAUD BOISTEL; DAVID HARING/DUKE LEMUR CENTER |
This made Fabre and her colleagues wonder how many other primate species had their fingers in their nostrils. The researchers searched the literature for previous studies and the internet for videos that documented the behavior.
"Most of the literature that we were finding was jokes," Fabre says. "I was really surprised, because there is a lot of literature on other types of pretty gross behaviors in animals, such as coprophagy," or poo eating (SN: 7/19/21). However, among the bogus articles, the team discovered some genuine reports of primate nose picking, including research conducted by Jane Goodall in the 1970s.
The researchers discovered that aye-ayes are the 12th known species of primate, including humans, to pick their noses and eat snot. Gorillas, chimps, bonobos, orangutans, and macaques are among the other species. Nose pickers are primates with exceptional dexterity and the ability to use tools.
"The team [has] given us the first map of nose picking across our primate family tree," Haslam says. "This immediately raises questions about how much of this behavior is happening out there, unseen or unreported." He recalls seeing a capuchin monkey pick its nose with a twig or stem (SN: 9/6/15).
"I'm surprised there aren't more reports on nose picking, particularly from zoos where animals are monitored on a daily basis," Haslam adds. "Perhaps because of our own social stigma, scientists are less likely to want to report nose-picking animals, or it may even be seen as too common to be interesting."