Sexual arousal: Sex matters
When it comes to sex, women are faced with a lack of hard facts. Consider the existence of an anatomical area known as the Gräfenberg spot (G-spot). Eleventh-century Indian texts and Cosmopolitan magazine seem sure it exists, and imaging studies of blood flow support its existence, but other studies find little evidence for it. Similarly, some evolutionary biologists think that the female orgasm has been influential in natural selection, helping sperm to travel upstream. But