From PEOPLE Magazine Click to enlarge
As a writer for Entertainment Weekly in his 20s, A.J. Jacobs suspected, "I never really accomplished anything—not counting my collection of air sickness bags from every major airline, which I'm proud of." Worse, his brain cells were expiring. "I knew a lot about Michael Jackson, but nothing about Andrew Jackson. I felt I'd be drooling into a bucket in five years."

So he did what anyone would: He read the entire Encyclopaedia Britannica, all 29 volumes (not including appendices). That adventure in geekdom is chronicled in his new memoir The Know-It-All: One Man's Humble Quest to Become the Smartest Person in the World. Soon Jacobs, 36, was tossing facts at his wife, Julie, 36, and friends at Esquire, where he is now an editor. Some favorites:
•During World War II, Londoners ate fish from the zoo.
•Ancient Egyptians mummified their cats and even mice, so the cats would have something to eat.
•Philosopher René Descartes had a fetish for cross-eyed women.
•Opossums have 13 nipples.

Julie began fining him $1 every time he inserted an irrelevant fact into a conversation. By the time he'd finished every volume 15 months later, he admits, "I owed her some serious cash."

Sometimes even trivia can be important, though: When the pair briefly had trouble conceiving, Jacobs relieved the stress by naming a fertility goddess of the week—like Anahiti, from Iran. Somewhere between A and Z, Julie got pregnant, and in March their son Jasper was born. "Diaper," Jacobs happens to know, originally meant a diamond-shaped architectural decoration. "But nothing in the encyclopedia," he says, "prepared me for how to change one."