Book excerpt: Teenagers reimagines the way people think about adolescents. No longer society's scourge and scapegoat, the teenager emerges from David Bainbridge's fascinating study as an awe-inspiring natural phenomenon that evokes reverence and wonder. Bainbridge, a veterinarian and anatomist, suggests that the second decade is the most important in the human lifecycle. In lively prose, he explains the science behind the changes that occur both on the surface of the teenage body and deep within the teenage brain, from lanky limbs and bad skin to falling in love, sleeping till noon, and the irresistible allure of sex, drugs, and rock'n'roll. Observed through a scientific lens, these bizarre biological transformations and behavioral anomalies snap into focus, as not only a beautifully choreographed sequence of steps on the path to adulthood, but also as a key evolutionary factor in the success of the species.