Feted and fetishised, the breast is an evolutionary masterpiece. But breasts are changing - they are getting bigger, arriving earlier and attracting newfangled chemicals. Increasingly, the odds are stacked against us in the struggle with breast cancer, even among men. In asking what makes breasts so mercurial - and so vulnerable - Florence Williams uncovers the latest science from the fields of anthropology, biology and medicine. Her investigation follows the life cycle of the breast, bringing her from a plastic surgeon's office, where she learns about the importance of cup size in Texas, to a laboratory where she discovers the presence of toxins in her own breast milk. Endowed with a witty and inquisitive voice, Williams explores where breasts came from, where they have ended up and what we can do to save them.