At a public lecture last fall, Mary Chisholm passed out samples of androsterone, a hormone in the testosterone family. "It's a rather interesting compound," she explains. "To some people it smells like musty camphor. To others it is entirely revolting. A third group smells nothing at all." Her audience that night, Chisholm remembers, ran happily true to form: "A third of them smelled camphor; a third were entirely revolted; and a third smelled nothing at all.