Madagascar’s Most Misunderstood Primate

The aye-aye may be one of the most interesting and misunderstood primates. With its odd looks, it has haunted villagers for centuries in its native Madagascar. While initially believed to be a completely different species, those native to the country believe the aye-aye is not an earthly creature at all. Instead, the maddening mind of the demonic aye-aye has become the stuff of ancient stories and nightmares.

Despite what local lore says about them, the aye-aye is not an aggressive animal. It prefers to be solitary, except for mating purposes, and is shy. However, based on appearance alone, it is understandable why the aye-aye might seem menacing to some people. Unfortunately, due to a combination of local superstition-driven killings and significant habitat loss from deforestation, the population of the aye-aye is struggling.

Meet the Aye-Aye

The aye-aye is the world’s largest nocturnal primate. However, because of how the aye-aye looks, when it was discovered in the 1700s, the aye-aye was thought to be a rodent related to the squirrel. It was not until the mid-1800s that the hairy brown aye-aye was determined to be related to the lemur, and subsequently reclassified as a primate.

Confusion over what species the aye-aye came from the external looks of the creature. With incisors that continuously grow and are used to chew through trees and a bushy tail like a squirrel, the natural instinct was that the aye-aye was a rodent. But when people like Sir Richard Owen began to look past the oddities that made the aye-aye such a remarkable creature, such as its large ears and eyes, it was easy to see that the aye-aye was not a rodent at all.

Thanks to Owen’s work as a naturalist, he was able to see that the aye-aye had opposable thumbs. Combined with its forward-facing eyes, these features helped Owen prove that the aye-aye—despite its rodent-like teeth, bat-like ears, bushy tail, and long, thin, highly flexible middle finger—was indeed a primate.

The aye-aye is the last of the genus Daubentonia, of which a giant aye-aye was once part of. The aye-aye itself was believed to be extinct until the 1950s when it was rediscovered. Today, the aye-aye is considered an endangered species, with a population in decline. However, captive conservation efforts are underway to help keep the aye-aye from disappearing forever.

Local Legend Calls the Aye-Aye Demonic

The aye-aye has long been thought to be a demonic creature in its native Madagascar. Local villagers believe that if the aye-aye points one of its bony middle fingers at them, they are marked for death.

Additionally, if an aye-aye enters a village and does not specifically point at a person, then the entire village is in peril. This is because unless the aye-aye is killed, death is imminent to at least one village member. Consequently, the aye-aye will be killed to keep any harm from coming to the village.

It is, in part, because of this fear that the aye-aye has become an endangered species, according to the IUCN. In fact, it was believed until the 1950s that the aye-aye had gone extinct. Other factors, such as extermination when aye-ayes are found in crops and ongoing deforestation, have also contributed to the species’ declining population.

It is difficult to determine how many aye-ayes remain in the wild. Some sources put the numbers as low as 1,000, while, thanks to breeding efforts outside of Madagascar, others state the population is around 10,000 strong.

While the fear of the aye-aye is deeply ingrained in the psyche of local villagers in Madagascar, the bony middle finger is not a sign of death. It does serve multiple purposes, however, that range from practical to peculiar.

Why the Aye-Aye Has a Bony Middle Finger

The aye-aye has six digits on each hand, including a pseudo thumb. The fingers are long and slender and make up 41% of the length of the aye-aye’s forearm, adding to the unique look of the primate.

What makes the fingers even more spectacular, however, is that the middle finger on each hand is significantly thinner and longer than the rest. This middle finger is used for a multitude of reasons from tapping on trees to determine where prey is hiding to clawing away bark from a tree when prey is located, as a hook to snare the prey, and even to pick its nose.

The middle fingers have a ball-and-socket joint, allowing them to rotate 360 degrees. This comes in handy when reaching into a tree to pull out a favorite meal of grubs.

Why the aye-aye uses its middle finger to pick its nose is still something of a mystery. Scientists have been developing theories for years, from relieving an itch to boosting the immune system, but have never been able to prove any.

What is known about the aye-aye picking its nose, according to a 2022 study published in the Journal of Zoology, is that the third finger is long and thin enough to make its way through the nasal passage and back to the throat. Scientists, like Roberto Portela Miguez, co-author of the study and the Senior Curator in Charge of Mammals at the Natural History Museum in London, were shocked to see that the aye-aye had the capability of moving through the nasal cavity with its finger to such depths.

“We were in for an even bigger surprise when we used CT scanning to see how the nose picking works internally, and the scan was mind-blowing,” Miguez explains to the Natural History Museum. “We were shocked from the reconstruction that the aye-aye’s finger could reach through its nose almost to the back of its throat.”

Scientists observed the aye-aye removing its finger from its nose and then using its mouth to examine what it had retrieved.

While the nose-picking aspect of why the middle digit is used is still unknown, what is clear is that, thanks to that same finger and its keen sense of sound, the aye-aye is capable of mentally mapping where prey is located no matter how little sound is made.

The Aye-Aye Can Mentally Map Where Prey Is By Sound Alone

In the same vein as woodpeckers, the aye-aye can hunt via percussive foraging. This means that sound is used to locate prey. Instead of a beak like the woodpecker, the aye-aye uses its long finger to make tapping noises on locations it believes prey is present.

To find its prey, the aye-aye searches through the forest canopy until it locates the right tree or branch. The aye-aye will then listen to see if any movement can be heard within a tree. If a grub makes any movement, the aye-aye will begin tapping the tree eight times per second with its middle finger, which has nerve endings that are pressure sensitive. Between the middle finger and sensitive hearing, the aye-aye can determine where there are irregularities within the tree.

When a grub location is found, the aye-aye will use its sharp incisors that perpetually grow to gnaw through the tree. Once enough progress is made and a hole is large enough to allow the middle finger to pass through, the middle finger will begin clawing through the rest of the bark in the tree. The finger will then hook the grub, extracting it from the tree, making for a portion of the meal that the aye-aye will find throughout the night during its nocturnal hunting and foraging.

The aye-aye is not a creature of doom. However, if conservation efforts are not intensified soon, this remarkable primate—related to lemurs—may face the same fate as its larger, now-extinct relative.

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