What's your type? Talk, dark and handsome? Short, bald and chubby? Muscular, unavailable and angry? How about Explorer, Builder, Negotiator or Director? These are the four personality types that anthropologist Helen Fisher coined during her research into why we fall in love with certain people but not others. According to Fisher, interpreting these types can help you navigate the dating ocean and net the perfect tuna (or man, if that's what you prefer).