They are our closest cousins and it has now been proven they also share our propensity for a good bottle of red. Scientists who conducted the research study at Bossou in Guinea West Africa found wild chimpanzees had adapted their behaviour to consume palm wine, a local tipple fermented at the top of palm trees inside improvised plastic gourds.
The study – published in the journal Royal Society Open Science – also showed African apes and humans share a genetic mutation that enables them to digest alcohol. It had been once thought only humans engaged in the voluntary and social consumption of alcohol until this discovery. The scientists found evidence of the long-term and recurrent consumption of fermented alcohol from the raffia palm (Raphia hookeri, Arecaceae) by primates from 1995 to 2012.
Chimpanzees at Bossou also consumed this alcoholic beverage, often in large quantities, despite an average presence of alcohol of 3.1% alcohol by volume rising to 6.9%. Raffia palms, which occur naturally in seasonally flooded areas are traditionally tapped by locals close to the crown of mature palms, which produces fermented palm sap year-round. The natural sugars in the palm sap quickly ferment into ethanol. Villagers at Bossou, Guinea install a modified plastic container (of 5–30 litres volume) to collect the dripping sap, and then cover the container with leaves to avoid contamination.
The tappers collect all the fermented sap from the container in the early morning and late afternoon, and it is usually consumed quickly (i.e. within 24 hours) without processing. The chimpanzees improvise using a leafy tool to scoop this fermenting sap. Collected data showed that the level of alcohol does not act as a deterrent to the primates’ drinking habits, supporting the idea that the last common ancestor of living African apes and modern humans was not averse to ingesting foods containing alcohol.
Drunk Disorderly Apes?
Dr Kimberley Hockings who led the research told BBC News: “Some individuals were estimated to have consumed about 85ml of alcohol, the equivalent of 8.5 UK units (approximately equal to a bottle of wine.)
“They displayed behavioural signs of inebriation, including falling asleep shortly after drinking. 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.”