Turns out that African apes and humans have more in common than previously thought. Observations made in the jungles of Guinea show wild chimps sipping alcoholic tree sap from leaf sponges, followed by some characteristically drunken behaviors.

A 17-year investigation led by Kimberley Hockings from Oxford Brookes University and the Centre for Research in Anthropology in Portugal now shows that humans are not the only apes who like to drink alcohol by choice; the new study, which now appears at Royal Society Open Science, provides the first direct evidence of wild chimpanzees voluntarily seeking out and consuming alcohol.

The chimps were observed to drink naturally fermented palm wine produced by raffia palm trees. Some drank so much that they exhibited “visible signs of inebriation,” such as falling asleep soon afterwards and restless, agitated behavior. Work by the researchers showed that some chimps consumed as much as 85 ml (2.87 US oz) of alcohol during a single drinking session. At about 3% alcohol by volume, that’s about the same as drinking an entire bottle of wine. Like humans, African apes have a genetic mutation that allows them to metabolize ethanol, or ethyl alcohol.

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The BBC offers some insights into how the apparent taste for alcohol speaks to our common predilection for the stuff:

Prof Richard Byrne, an evolutionary biologist from the University of St Andrews, commented that the evolutionary origin of [the alcohol metabolizing] gene could be that it “opened access to good energy sources - all that simple sugar - that were accidentally ‘protected’ by noxious alcohol”.

“And presumably, whatever its evolutionary origin, it is that adaptation which makes me able to enjoy a good malt,” he added.

Dr Catherine Hobaiter, from St Andrews University, said: “It would be fascinating to investigate the [behaviour] in more detail: do chimps compete over access to the alcohol? Or do those who drank enough to show ‘behavioural signs of inebriation’ have a bit of a slow day in the shade the next morning?”

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Sounds like a good excuse for some further field work.

Read the entire study at Royal Society Open Science: “Tools to tipple: ethanol ingestion by wild chimpanzees using leaf-sponges.”


Contact the author at george@io9.com and @dvorsky. Top image by G. Ohashi

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