What good is a rattlesnake? What purpose do animals serve? All species play a vital role in their biological communities, and the removal of just one can have a noticeable and catastrophic ripple effect.Yet social and political pressures frequently pit species conservation against economic progress and prosperity, and scientists fear that we may be in the midst of a mass extinction event. Brian R. Chapman and William I. Lutterschmidt make the case that the effort to preserve animal...