Clothes moth larvae snack on hair from corpses, providing police with genetic clues.

Learning mathematics may make the brain reorganize the way it works.

“What makes a man?” Flam, a science writer who pens a sex column for The Philadelphia Inquirer, seeks a scientific answer to this often-asked question. Her search takes her from a seduction boot camp for men to the labs of evolutionary biologists, sociologists and physiologists who study gender differences. From mushrooms with 30,000 sexes to sea worms that compete to be the male, Flam surveys the natural world to explain why human males evolved the way they did, revealing a riotous diversity in the way life begets life. While human males have one X and one Y chromosome, for inst...