You might think your mates act like chimps once they’ve had too much hooch, and you might be closer to the truth than you’d think. Wild chimps have been found boozing on wine in the forests of West Africa, and seem to have formed a habit of it.
The study, published in the Royal Society journal Open Science, describes how the wild chimpanzees of Bossou in the West African country of Guinea are partial to a little tipple of palm wine. Well, slightly more than a little tipple really—one was recorded drinking over three liters in one sitting. Using leaves as sponges and scoops, the primates were shown to engage in habitual drinking, defined as quaffing the booze on different occasions.
The wine sampled ranged in strength, sitting at an average of around 3% alcohol by volume (ABV)—comparable to a light beer—but rising to an impressive 7% ABV, meaning the primates were probably feeling fairly well oiled by the end of their drinking sessions. They were drunk enough for the scientists watching the apes to report that they “displayed behavioural signs of inebriation.”
In the region where the researchers were studying the chimps, local people harvest the palm wine by making wedge-shaped cuts into the tree's trunk, allowing the sugary sap that seeps out to gather in large containers. The villagers then collect the fermented sweet liquid in the mornings and evenings, as the alcohol concentration rises too high if left any longer.
This gives the cheeky chimps plenty of time during the day to raid the bar. Despite being watched round the clock, the researchers found that the apes were exclusive day drinkers, sleeping off the buzz at night. Although we don't know whether they experience the same savage hangovers as humans, it seems they may experience restlessness at night like us. The main boozer of the group, for example, is reported to have acted agitated whilst trying to catch some Z's and would take an extra hour to settle down after the sun had set.
The team, a collaboration of researchers from different institutions, looked over observations of the community of chimps from the past 20 years. They found evidence of 51 wine-drinking events within the group of 26 apes. Whilst they can’t be certain that the chimps actually got drunk, they consumed enough alcohol to equate to around 8.5 UK units—equivalent to around 1 bottle of wine—and showed signs of drunken behavior.
The study gives an insight into the origin of alcohol drinking in humans. It adds weight to the “drunken monkey hypothesis” that the enzyme needed to digest ethanol, alcohol dehydrogenase, evolved around 10 million years ago in the common ancestor to both chimps and humans, around when animals started eating fermented fruit from the forest floor. Although it seems that the apes can quite easily get a taste for the strong stuff, reports are as yet unconfirmed if the chimps then went for a “cheeky Nando’s” with the lads.
Main image credit: Tambako The Jaguar/flickr CC BY-ND 2.0