Love at first sight . . . hooking up . . . jealousy . . . adultery. . . . Helen Fisher explains it all in this thought-provoking anthropological view of human sexual and romantic behavior. Examining marriage and divorce in fifty-eight societies, infidelity in forty-two cultures, and new national studies of singles in America, she argues that we are returning to patterns of sex, romance, love, and attachment that echo our ancient past. This classic book has been updated throughout to include her revolutionary work on the brain in love, love addictions, and why we are biologically drawn to specific partners, and includes a new chapter on future sex.