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Abstract

In the last common ancestor of modern humans and the three living African ape species a genetic mutation occurred that increased the rate that alcohol was metabolized. This fact initially supports the "drunken monkey hypothesis" which states that natural selection should have favoured individuals that routinely incorporated alcohol- and thus energy-rich fruits into their diet. However, random observations from apes living in the wild do not provide evidence for such kind of choosey feeding behaviours. To investigate whether or not the living great apes have evolved a preference of alcohol-rich fruits over normal ripe fruits we performed a bioassay with captive chimpanzees offering them apple puree with and without rum flavour. Initially, the chimpanzees were curious about the alcohol-flavoured apple puree and feed on it when it was presented to them for the very first time. Once tasted, however, they lost interest in it indicating that chimpanzees are able to perceive, but do not prefer alcohol-rich fruits more than non-alcoholic fruits. Thus, we think that for our hominoid ancestors from the late Miocene the possibility to consume alcohol-rich fruits was helpful to survive periods of food scarcity, but did not lead to a genetic predisposition for alcohol.