This book contains a collection of 12 articles first printed in the magazine Scientific American. These articles show how life manages to eke out an existence where, by all rights, it shouldn't and helps in explaining the roles of energy and the building-block elements in the cycles of life. The titles include: (1) "The Evolution of the Earliest Cells" (J. William Schopf); (2) "Emergence of Animals" (Mark A. S. McMenamin); (3) "Symbiosis in the Deep Sea" (James J. Childress, Horst Felbeck, and George N. Somero); (4) "Antarctic Fishes" (Joseph T. Eastman and Arthus L. DeVries); (5) "Intertidal Fishes" (Michael H. Horn and Robin N. Gibson); (6) "Thermoregulation in Winter Moths" (Bernd Heinrich); (7) "The Physiology of the Koala" (Robert Degabriele); (8) "Carnivorous Plants" (Yolande Heslop-Harrison); (9) "Communication between Ants and Their Guests" (Bert Holldobler); (10) "Slavery in Ants" (Edward O. Wilson); (11) "How the Trypanosome Changes Its Coat" (John E. Donelson and Mervyn J. Turner); and (12) "Viroids" (T. O. Diener). (KR)