Scientists who study chimpanzees in the Republic of Guinea, have seen proof of recurrence and long-term binges of ethanol by apes.
The 17-year study chronicled chimps drinking fermented palm sap with the use of leaves, with some drinking enough alcohol resulting to “visible signs of inebriation”.
The journal Royal Society Open Science, which published the study, revealed their drink of choice is produced by raffia palm trees which is a naturally fermented palm wine.
This research took place in Bossou, Guinea, wherein “palm wine” are harvested by local people from trees, by tapping them at the crown and collecting the sap in containers, which they gather during mornings and evenings.
Researchers witnessed chimpanzees climbing the trees, usually in groups, to drink the naturally fermented palm sap.
Leaf sponges, a handful of leaves that they chew and crush to fashion into an absorbent sponge, were used as drinking tools by the chimps, by dipping into the liquid and sucking out the contents.
Dr Kimberley Hockings, the research team leader from Oxford Brookes University and Centre for Research in Anthropology in Portugal, examined that sap was about 3% alcohol by volume.
“Some individuals were estimated to have consumed about 85ml of alcohol, the equivalent to 8.5 UK units or approximately equal to a bottle of wine,” she said.
“They displayed behavioral signs of inebriation, including falling asleep shortly after drinking,” she added, “on another occasion after drinking palm wine, one adult male chimpanzee seemed particularly restless.”
In an interview with BBC news, the researcher said, “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.”
Alcohol could prove to be toxic and this is the first time that researchers were able to record and measure voluntary alcohol ingestion in any wild ape.