This Lemur’s Creepily Long Finger Is Perfect for Nose-Picking

This Lemur’s Creepily Long Finger Is Perfect for Nose-Picking

Lemurs use their long middle fingers to pick their noses, which is a first for the species. But scientists aren’t sure why these animals picked up the habit

An aye-aye nose-picking. Credit: Anne-Claire Fabre

A long-fingered lemur was caught on camera picking at its nose and eating slimy foods.

The culprit was Kali, an aye-aye (Daubentonia madagascariensis) at the Duke Lemur Center who now has the dubious honor of being the first of her species ever observed nose-picking, researchers say. This is all made more impressive by the fact that aye ayes use their unusually long middle fingers to pick her nose. Kali reached her throat when she had her entire middle finger in her nose. Anne-Claire Fabre is an evolutionary biologist at University of Bern and curator of mammals at Natural History Museum Bern. “I was really impressed,” she says. She and her colleagues reported the findings in the Journal of Zoology.

Fabre was studying lemur grasp when she happened to catch Kali “digging for gold.” She and her team subsequently searched in the research literature for other examples of primate nose-pickers and found that at least 12 species are guilty of the habit. Others include chimpanzees, gorillas, capuchin monkeys and, yes, humans. Surveys found that nose-picking is very common in humans. Nearly all of the sampled teens and adults admitted to it privately.

This CT-scan reconstruction shows an aye-aye picking its nose.
This CT-scan reconstruction shows an aye-aye picking its nose. Credit: Renaud Boistel

But, if there is a champion nose-picker it has to be the ayeaye. The middle fingers of these lemurs are more than three inches in length and very spindly. Adam Hartstone-Rose from North Carolina State University, who was not involved with the new research, said that Aye-ayes use these unusual digits in their nocturnal hunts to find bugs. They tap on logs at a staggering seven raps per seconds, listening with batlike ears to the sound of hollows in the wood–tunnels gnawed and gnawed insects. They then mentally map the tunnels, digging holes at intersections to find grubs. Hartstone-Rose explains that fingers in the animal kingdom are almost always composed of hinge joints that bend forward and back. However, the middle finger joint of the aye aye is a ball and socket, which allows it to turn and rotate almost like a human shoulder.

Some researchers speculate that nose-picking may have immune benefits or other benefits, but Fabre says that there is no solid science to support that. Hartstone-Rose states that primates are pickers in general. They pick at parasites and put Q-tips in their ears, picking at scabs and generally use their dexterity and grooming skills to groom others and themselves.

“I think the finger evolved to do this amazing fishing behavior” in logs, Hartstone-Rose says, “and just because it has that anatomy and that sensitivity it basically freed it to be able to do this other disgusti

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