It seems even chimpanzees like to party. Researchers have observed chimpanzees in West Africa get drunk during long "drinking sessions," where they drink the fermented sap from palm trees, which is normally used to make palm wine.

In the new study, published in the journal Royal Society Open Science, researchers focused on primates living in Guinea and observed the chimps using palm fronds as tools to soak up the fermented sap of raffia palms, which can contain up to 6.9 percent alcohol making it stronger than most beers.

"The habitual and voluntary consumption of ethanol has been documented until now, only in humans," apart from anecdotal observations in wild apes, said Kimberley Hockings of Oxford Brookes University, one of the report's coauthors.

Now, it seems, that humans are not alone in their consumption of alcohol. While baboons in South Africa are known for stealing fermenting grapes from vineyards, and monkeys are known to steal the odd cocktail here and there from unsuspecting tourists at local resorts, the chimpanzees in Boussou are unique because their alcohol consumption is not due to any interaction with humans, says the report.

It also seems that some chimps consume more alcohol than others. According to the report, some of the chimps "consumed significant quantities of ethanol and displayed behavioural signs of inebriation." Researchers did note that no detailed data on their behavior was recorded after the chimps had a few drinks, they noted that "some drinkers rested directly after imbibing fermented sap."

"On another occasion after drinking palm wine, one adult male chimpanzee seemed particularly restless."

"While other chimpanzees were making and settling into their night nests, he spent an additional hour moving from tree to tree in an agitated manner. Again pure speculation, but it's certainly something we would like to collect further data on in the future," the researchers say.

This behavior is still considered very rare, according to Hockings. In order to determine their findings, researchers had to combine their data from other observations dating back to 1995. Researchers said they observed 51 different "drinking events" by individual primates over that period of time.

"One adult male in particular accounted for 14 or 15 events," Hockings says. So it seems that even in the world of the chimpanzee, there is still that one individual who drinks too much.