Chimpanzees. They’re much like us genetically, anatomically and, as it turns out, cocktailogically. Because we finally have solid evidence that chimps drink alcohol. So say researchers who have observed wild chimpanzees throw back fermented tree sap. The findings are served up in the Royal Society journal Open Science. [Kimberley J. Hockings et al, Tools to tipple: ethanol ingestion by wild chimpanzees using leaf-sponges]

Some biologists think that the reason we humans like adult beverages is because our primate ancestors were partial to super ripe fruits, which are high in calories and often in ethanol. But there’s one big problem with this so-called drunken monkey hypothesis: apes had not really been seen downing alcohol in the wild. That is, until now.

The researchers were studying chimps in Bossou, west Africa. In this region, people tap palm trees and allow the collected sap to ferment in small plastic containers, which they cover with leaves to prevent contamination.

Turns out, for chimps who hanker hooch, the leaves are like the straw in a banana daiquiri—the apes take the leaves, crumple them up, dip them in the sap and then suck them dry.

The drinkers were mostly male, shockingly, accounting for 34 of the 51 bouts of boozing observed, and they’d consume a couple of liters of the fermented brew each time they bellied up to the bar. I mean tree.

Whether chimps are simply taking advantage of an easily acquired, calorie-rich liquid or they especially enjoy the sap’s sweet flavor—or intoxicating effects—is not known. But the questions call for another round—of research.

—Karen Hopkin

[The above text is a transcript of this podcast.]