Snippet: The authors of the BioScience paper propose that metabolizing ethanol may let African apes safely eat the ripe, fermented fruit they find on the ground. This adaptation could free them from competing with monkeys for unripe fruit in trees. It also could spare large apes the risk of climbing and possibly falling out of trees, which a 2023 study by Dominy and Fannin reports is dangerous enough to have influenced human physiology.

Given that chimpanzees consume about 10 pounds of fruit each day, the team's analysis suggests they ingest a nontrivial amount of alcohol, Dominy says. That level of intake suggests that chronic low-level exposure to ethanol may be a significant component of chimpanzee life, and a major force of human evolution.