Although scientists have discovered many fundamental physiological and behavioral mechanisms that comprise the stress response, most of current knowledge is based on laboratory experiments using domesticated or captive animals. Scientists are only beginning, however, to understand how stress impacts wild animals - by studying the nature of the stressful stimuli that animals in their natural environments have adapted to for survival, and what the mechanisms that allow that survival might be. This book summarizes, for the first time, several decades of work on understanding stress in natural contexts. The aim is two-fold. The first goal of this work is to place modern stress research into an evolutionary context. The stress response clearly did not evolve to cause disease, so that studying how animals use the stress response to survive in the wild should provide insight into why mechanisms evolved the way that they did. The second goal is to provide predictions on how wild animals might cope with the Anthropocene, the current period of Earth's history characterized by the massive human remodeling of habitats on a global scale. Conservation of species will rely upon how wild animals use their stress response to successfully cope with human-created stressors.

In social relationships-whether between mates, parents and offspring, or friends-we find much of life's meaning. But in these relationships, so critical to our well-being, might we also detect the workings, even directives, of biology? This book, a rare melding of human and animal research and theoretical and empirical science, ventures into the most interesting realms of behavioral biology to examine the intimate role of endocrinology in social relationships. The importance of hormones to reproductive behavior-from breeding cycles to male sexual display-is well known. What this book considers is the increasing evidence that hormones are just as important to social behavior. Peter Ellison and Peter Gray include the latest findings-both practical and theoretical-on the hormonal component of both casual interactions and fundamental bonds. The contributors, senior scholars and rising scientists whose work is shaping the field, go beyond the proximate mechanics of neuroendocrine physiology to integrate behavioral endocrinology with areas such as reproductive ecology and life history theory. Ranging broadly across taxa, from birds and rodents to primates, the volume pays particular attention to human endocrinology and social relationships, a focus largely missing from most works of behavioral endocrinology.