A research team studying chimpanzees, the closest primitive cousins of the humans, in the Republic of Guinea has found evidence suggesting recurrent and long-term consumption of ethanol by the animals. The 17 year long study has found that the chimps use leaves for drinking alcoholic palm sap. That’s not all; some have been found to drink enough fermented sap for showcasing prominent signs of inebriation.
The study, which has recently been published in the science journal Royal Society Open Science, has revealed that the chimpanzees are fond of naturally fermented wine extracted from raffia palm trees.
The said research was conducted in the Bossou region of Guinea; natives of this place are known for harvesting wine from palm trees. For those who don’t know: the harvesters first tap the trees at their crown and then gather the sap in containers.
The research team working in this region has often witnessed chimpanzees climbing up the palm trees and drinking naturally fermented sap produced by the trees. The apes usually invade the trees in groups.
The researchers also found that the chimps use leaf sponges as their drinking tools. Leaf sponges are absorbent sponges the chips made by chewing and crushing a handful of leaves. According to the researchers, the chimps dip these sponges into the plant sap and finally suck the soaked contents out.
To find out up to what extent the chimps engaged in alcohol consumption, the researchers measured the level of alcohol in the wine collected in containers and captured videos of the Apes drinking sessions. They found that the plant sap contained around 3 percent alcohol by volume.
The study’s lead author Dr. Kimberley Hockings said that some of the chimpanzees were found to consume around 85-ml alcohol, which is equivalent to a full bottle of wine. Dr. Hockings further informed that consumption of that much alcohol resulted in behavioral signs of inebriation in those chimps, which include falling asleep within a few minutes of drinking the sap.
She has also mentioned another instance during which an adult male chimp showcased restless behavior after drinking naturally fermented plant sap. Unlike others in his group, who were gradually settling in their respective night nests, he kept on moving from one tree to another agitatedly.