A photograph shows a gorilla about to attack a photographer.
The gorilla was not drunk from eating too much bamboo.
In February 2015, an image allegedly showing a drunk gorilla throwing a punch at a photographer went viral.
The photograph was taken by wildlife photographer Christophe Courteau at Volcanoes National Park in Rwanda and was originally posted by the Caters News Agency along with a story about the potentially dangerous encounter:
These incredible pictures show the moment a lairy gorilla PUNCHED a photographer in a drunken rage.
Unlucky wildlife photographer Christophe Courteau, 46, was taking snaps of a group of silverback gorillas in the forest of the Volcanoes National Park, in Rwanda, when the alpha male of the family began to charge at him unexpectedly.
In a scene reminiscent of a bar brawl, the 250kg mountain gorilla, named Akarevuro, appears to clench his fist tightly before tackling the photographer in a display of wanton aggression.
Remarkably, Chris managed to capture the gorilla on camera moments before the attack on the slopes of the Virunga Mountains.
Completely drunk from eating bamboo stems, which ferment in gorillas' stomachs causing them to become intoxicated, the primate, who is the leader of the Kwitonda Group, is said to have felt threatened by a rival male, causing him to become excitable and defensive of his territory.
While Caters News Agency had several photos illustrating that a brief gorilla-photographer altercation occurred, researchers at Smithsonian Magazine took issue with the claim that the gorilla was drunk on bamboo, explaining that it is impossible for bamboo to ferment in a gorilla's stomach:
There's only one hitch to the tale: It's impossible for a mountain gorilla to become intoxicated from eating bamboo.
"The suggestion that these gorillas were drunk from fermenting bamboo in the stomach is misleading," says Joanna Lambert, a professor of biological anthropology at the University of Texas at San Antonio. "They just don't have that kind of stomach."
The stomach of a gorilla is like the stomach of a human, in that it is full of digestive acids. It contains no fermenting bacteria, making it impossible for fermentation to occur within the stomach itself. As in humans, fermentation can occur in a gorilla's large intestine, but even that wouldn't render a gorilla drunk. According to Lambert, the process is a completely different kind of fermentation than the one that produces alcohol.
A more plausible scenario is that the gorilla was on a sugar high. Some foods, like bamboo, can contain lots of sugar, which translates to more readily available energy when consumed. If the gorillas had eaten a lot of bamboo, Lambert says, they might have appeared more energetic than usual, but they definitely weren't drunk.
This wasn't the first time that claims about "drunk" gorillas had circulated online. In 2009, the Daily Mail published a series of images taken by wildlife photographer Andy Rouse in the Rwandan mountains. Similar to Courteau's encounter (although lacking a physical altercation), the gorillas were observed acting drunk:
"I had heard they sometimes get like this, but I had never actually seen it. It was just like any family party when one or two members have a little bit too much to drink.The boss of the group, a huge silverback called Kwitonda, and some of the younger males were completely out of it."
Both Courteau's and Rouse's claims were based on their observations, and no one disputed the fact that those gorillas were acting "funny." But according to Lambert, acting funny is not the same thing as actually being drunk:
"There are all kinds of 'forest legends' of animals like elephants getting drunk, and for the most part that's not happening," Lambert says. An exception can be when a fruit drops from the parent tree and begins to ferment due to yeast on the outside of its skin — that would make the fruit mildly alcoholic. "But that's a completely different kind of system," Lambert says, "and that's not what's happening [in the photographs]."