Drunk: How We Sipped, Danced, and Stumbled Our Way to Civilization

by Edward Slingerland

When it comes to explaining our taste for alcohol, perhaps the most prominent hangover theory is the “drunken monkey” hypothesis advanced by the biologist Robert Dudley.34 In the tangled rain forests where humans first evolved, alcohol is produced in ripe fruit by yeast cells as part of their chemical warfare campaign against bacteria, which are less tolerant of alcohol and compete with the yeast for the fruit’s nutrients. Alcohol therefore owes its very existence to a vicious history of yeast-bacteria warfare. Dudley argues that an incidental feature of the molecule that we call alcohol (technically, ethanol) is the key to why primates acquired a taste for it. Ethanol is extremely volatile—that is, it is a small, light molecule that can travel long distances in the air. It is therefore ideally positioned to function as an olfactory dinner gong for a wide variety of species. This no doubt includes fruit flies, whose taste for alcohol is probably linked to its ability to lead them to fruit. It is Dudley’s contention that this was also the case for early humans, as well as our primate ancestors and cousins, who—following the waft of alcohol molecules to find and identify the rare prize of ripe fruit—came to associate small amounts of alcohol with high-quality nourishment.