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Despite Folklore, Elephants Might Be Lightweights When It Comes to Booze

New study finds elephants lack a genetic mutation that allows humans to efficiently break down alcohol

Elephants are missing a gene to digest alcohol, which might mean they probably can't handle their liquor. (Xinhua/Yang Zongyou Images)
smithsonianmag.com

Whether it’s too good to be true or stranger than fiction, people want to believe in drunken elephants.

Recently, a story about elephants getting drunk and passing out in a field of tea plants went viral only to be proven false, according to Arijeta Lajka who fact-checked the story for the Associated Press.

The veracity of this latest tale of inebriated pachyderms aside, humans have been swapping stories about wasted elephants for hundreds of years.

The writings of the 19th century French naturalist Louis-Adulphe Delegorgue who travelled Africa in the 1830s report stories from Zulu guides of elephants getting tipsy off the fermented fruits of the marula tree, according to Jason Goldman’s 2014 story for BBC Future. "The elephant has in common with man a predilection for a gentle warming of the brain induced by fruit which has been fermented by the action of the sun," wrote Delegorgue.

But are these stories true?

In 2006, a trio of scientists took on this oft recited bit of lore concerning the fruit of the marula tree. They concluded it was just a myth. The rationale was that an elephant would be physically incapable of consuming the mountain of fermented pulp necessary for the 6,000-pound animal to catch a buzz.

But now, researchers think this study may have erred in assuming that elephants are just giant humans when it comes to processing alcohol. New research, published last month in the journal Biology Letters, suggests elephants are more than capable of getting drunk. In fact, elephants might be, along with armadillos, cows and numerous other mammals, total lightweights, reports Susan Milius for Science News.

Humans produce an enzyme called "alcohol dehydrogenase class 4" that breaks down ethanol, the chemical name for booze’s active ingredient, allowing our bodies to metabolize alcohol 40 times faster than some other primates, writes Mareike Janiak, a primate geneticist at the University of Calgary and one of the authors of the new study, in the Conversation.

The genetic basis of this magical enzyme that lets humans push their luck with multiple boozy beverages is a gene called ADH7. This adaptation appeared some 10 million years ago in a primate ancestor we share with gorillas and chimpanzees. Janiak speculates the enzyme may have allowed our ancestors to indulge in fermented fruit from the forest floor without keeling over.

To see which other animals share humans’ ability to tolerate alcohol, Janiak and her co-authors compared the ADH7 gene across 85 mammals.

The study found evidence that humans may have drinking buddies among fruit eating mammals. Researchers found six species with mutations to ADH7 similar to the one that allows humans to cope with alcohol, including fruit and nectar eating bats called flying foxes and freaky-looking lemurs called aye-ayes.

But researchers found humans could likely drink most animals under the table, since the majority lacked the variation in ADH7 that allows our species to rapidly breakdown ethanol. Elephants were among a significant chunk of mammals that had non-functional ADH7 genes, suggesting their bodies may have little recourse when ethanol shows up.

The common thread amongst these species with ADH7 “switched off” is diet, according to the researchers. Members of this group mostly eat plants—as in the case of cows, goats, beavers and elephants—or meat—as in dogs, sea lions and dolphins, per the Conversation.

Elephants may be unique among this cadre of animals in that they will opportunistically gorge themselves on fruit.

Chris Thouless, a researcher with the nonprofit Save the Elephants, tells Rachel Nuwer of the New York Times that modern forest elephants regularly track down and eat fruit, but that, evolutionarily, it’s a recent addition to their menu—elephants became grass specialists roughly eight million years ago and incorporated fruit and other foods around one million years back. This might explain the non-functionality of elephants’ copy of ADH7.

Janiak notes that her study may not close the book on elephants’ drinking prowess, or lack thereof, because pachyderms might metabolize ethanol through some other biochemical process.

Case in point, some tree shrews consume large quantities of fermented nectar about as strong as a weak beer but never appear intoxicated despite lacking humans’ special ADH7 mutation, Amanda Melin, a molecular ecologist at the University of Calgary and co-author of the study tells the Times.

But when it comes to elephants, the point is that it’s unlikely the mammoth mammals process alcohol just as efficiently as humans, writes Janiak in the Conversation. “Simply scaling up for body size does not accurately predict whether elephants can become intoxicated from eating old marula fruit.”

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