Anthropologist Helen Fisher studies love: its evolution, its biochemical foundations and its vital importance to human society. She outlines the three stages of love (lust, infatuation and long-term attachment), shedding light on eternal questions like why we love, and why we cheat. She also discusses the natural talents of women, and their new significance in the modern world. She ends with a warning about the widespread use of antidepressants — and a truly hilarious story of romantic pursuit.