Overview

• Published in Science Advances, the UC Berkeley–led study quantifies daily ethanol intake in wild chimpanzees for the first time.
• Ethanol in ripe fruit pulp was measured across about 20–21 species at Ngogo, Uganda, and Taï, Côte d'Ivoire, with average concentrations near 0.26–0.32% by weight.
• Based on diet data indicating roughly 4.5 kilograms of fruit consumed daily, researchers estimate about 14 grams of ethanol per chimpanzee per day.
• The intake equals about one U.S. standard drink, which scales to nearly two drinks when adjusted for a typical human’s body mass.
• Observers report no obvious intoxication because fruit is eaten throughout the day, and while the findings bolster the ‘drunken monkey’ hypothesis, whether chimpanzees actively seek higher-ethanol fruits remains unresolved.