‘Drunken monkey’ theory backed up by boozy chimps

Researchers in west Africa have stumbled upon a surprisingly popular primate pub. It seems chimpanzees from Guinea enjoy sampling the milky sap of raffia palms, which ferments into an alcoholic tipple and is tapped by local humans.

Following 17 years of observation, 51 ape drinking events involving 13 chimps, young and old, were recorded by the researchers.

The local apes showed great ingenuity when it came to wetting their whistle. They would mould leaves in their mouths, turning them into spongy pads perfect for dipping into the containers set out by the humans to catch the sap.

Tests show the alcoholic content of the syrup ranged from 3.1% all the way up to 6.9% – enough to get the diminutive apes well on the way. Some were seen drinking the equivalent of eight-and-a-half UK units – the best part of three pints of Stella Artois.

As the scientists put it, the chimps “consumed significant quantities of ethanol (alcohol) and displayed behavioural signs of inebriation”.

In general, this would manifest itself in sleepiness, but on one occasion a chimp was seen moving from tree to tree in an agitated state. We’ve all been there.

The behaviour of the apes varied, with some drinking alone atop the palm, but on 20 occasions the apes indulged in extended “drinking sessions” where several would attend.

The research gives credence to the “drunken monkey” theory, which suggests that apes and humans can break down alcohol thanks to a common ancestor.

This ancestor, the theory goes, would need to eat fermented fruits to provide additional calories in environments where more readily digestible food was scarce.

This follows on from research revealed last week that suggests that chimps could cook, if given the chance.

Throw in their newly found fondness for booze and you’re well on the way to a tolerable ape dinner party.  

Image: Tambako via Creative Commons

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