Book excerpt: Overlooked in the early accounts was that all organisms face many additional types of natural challenges and obstacles in their efforts to survive and reproduce: for example, they must fight or escape predators, replenish diminished food supplies, and anticipate, seasonal changes of climate. Weiner's survey of the literature shows that much progress has been made in understanding the effects of exposing animals to these kinds of naturally occurring stressful experiences and their varied outcomes. Under such conditions there appear patterns of integrated behavioral and physiological responses that are exquisitely attuned to the experience. He carefully assesses the research on the ways in which neural circuits and peptidergic mechanisms in the brain generate and integrate these patterns. In addition, he presents new concepts about the perturbation of subsystems, including biological clocks, which may, or may not, lead to disease or ill-health.