Worldwide, people drink over 65 billion gallons of alcohol each year. The United States’ share, if divided equally across the adult population, would amount to about two and a half gallons of pure alcohol per person, annually. And this thirst seems to be universal: Fermented beverages have been found in nearly every society, as far back as archaeologists can detect their existence.
That’s the idea behind the “drunken monkey” hypothesis, formulated by biologist Robert Dudley in 2000.
According to the hypothesis, our pre-human ancestors regularly ingested small amounts of alcohol because the substance is produced when ripe fruit or nectar is decomposed by wild yeast. Through natural fermentation, yeast feeds on plant sugars and produces waste products of CO2 and ethanol — the chemical name for alcohol.
