"The coming-of-age experience has changed dramatically, with girls maturing sooner than ever. But what happens when a girl has the body of a 13-year-old and the brain of an 8-year-old? Contrary to popular wisdom, early puberty is not merely a reflection of physical changes--it's deeply psychological, too, with effects that can put a girl at higher risk for behavioral problems and long-term health challenges, such as obesity, depression, eating disorders,...