Joan Acocella notes that “hangovers are probably as old as alcohol use, which dates back to the Stone Age” (“A Few Too Many,” May 26th). But the biological basis of the hangover goes back even further. In “Descent of Man,” Darwin states, “Many kinds of monkeys have a strong taste for . . . spirituous liquors.” And he cites the reported effects of the monkeys’ being exposed to strong beer—“cross and dismal . . . aching heads . . . a most pitiable expression”—as suggestive evidence for the evolutionary affinity between humans and primates. “These trifling facts prove how similar the nerves of taste must be in monkeys and man, and how similarly their whole nervous system is affected”—by alcohol.

Léo F. Laporte

Professor Emeritus, Earth Sciences

University of California, Santa Cruz

Redwood City, Calif.