Biologists find that, given the choice, both aye aye lemurs and slow lorises will choose the most intoxicating drink when presented with different options

They were once considered merely lazy and adorable. But new research into the antics of the slow loris has revealed a wilder side to the docile creatures. Given the chance the innocent-eyed beasts will neck the most alcoholic drinks they can lay their paws on.

The ability of the slow loris to seek out the most potent brew in reach was discovered by researchers in the US who wanted to know whether the animals favoured highly-fermented nectar over the less alcoholic forms secreted by plants in their natural habitats. As sugary nectar ferments in the wild, its calorie content rises, making it a potentially more valuable source of energy.



In a series of tests with Dharma, an adult female slow loris, biologists at Dartmouth College in New Hampshire found that when presented with a choice of sugary solutions laced with different amounts of alcohol, the loris speedily settled on the most intoxicating.



But while the animal was quickly drawn to the nectar substitutes, which contained between 1% and 4% alcohol, the slow loris displayed what the researchers describe as “a relative aversion to tap water”, which was used as a control.



Dharma was not alone in her taste for drink. The scientists ran the same series of experiments with two nocturnal aye aye lemurs, a male called Merlin and a female called Morticia. Once again, the primates homed in on the most alcoholic of sugary solutions the researchers knocked up to mimic fermented nectar.



Facebook Twitter Pinterest Aye ayes collect nectar using an extraordinary finger that swivels on a ball and socket knuckle joint. Photograph: David Haring

For the study, Samuel Gochman and his colleagues poured various nectar-like solutions into containers that slotted into recesses in a round table in the animal enclosure. To make sure the primates did not simply remember the position of the most alcoholic drink, the pots were moved around before each trial.



To get to the alcoholic drinks, Dharma, Morticia and Merlin had to insert a finger through a hole in the lid of each container. The task mimics the natural collection of nectar in the wild, which the aye aye performs with an extraordinary finger that swivels on a ball and socket knuckle joint. Aye ayes spend about a fifth of their feeding time in the wet season feasting on nectar from the Ravenala or traveller’s tree in Madagascar. Meanwhile in Malaysia, fermented nectar from Bertram palms can make up more than 40% of a slow loris’s diet.

Writing in the journal Royal Society Open Science, Gochman notes that the aye ayes repeatedly tried to get more out of pots they had already emptied. “Compulsive digital probing for residual traces of alcohol suggests a strong attraction or craving,” they write.



Gochman, a biology student at Dartmouth said that despite their taste for alcohol, the animals did not appear to suffer any detrimental consequences from imbibing. “No signs of inebriation were observed,” he said.



In the case of the aye ayes, at least, the animal’s tolerance of alcohol may come from a genetic mutation that the species shares with the last common ancestor of African apes and humans. The mutation dramatically speeds up the rate at which alcohol is broken down in the body. “The results indicate that the mutation might confer a preference for alcohol,” Gochman said.