Wild chimpanzees share fermented fruits.

The use of fermented foods and drinks by humans is so widespread as to be considered ubiquitous, with their use largely linked to dietary benefits and social bonding123. The discovery of a molecular adaptation in an alcohol dehydrogenase enzyme that greatly increased ethanol metabolism in the common ancestor of African apes suggests that the incorporation of fermented fruit in the human diet has ancient origins4. However, little is known about the inclusion of ethanolic foods in the diet of nonhuman great apes. Here, we document for the first time the repeated ingestion and sharing of naturally fermented African breadfruit (Treculia africana) with confirmed ethanol (alcohol), by wild chimpanzees (Pan troglodytes verus) in Cantanhez National Park, Guinea-Bissau. Widespread plant food sharing in great apes and the recent confirmation of ethanol presence in diverse fruit species5 suggest the sharing, and dietary incorporation, of ethanol-containing foods is extensive and may have played a long-standing role in hominoid societies.