To persevere across far-ranging environments is profoundly human, but life at the extremes is constrained in extraordinary ways. The diversity of environments in which people are found, either as permanent inhabitants or as temporary visitors, ranges from the high Andes to the scorched Sahara to the frigid Arctic, yet these places are a small fraction of those that harbor life in the thin biosphere around the planet's surface. Most of Earth is too inhospitable for even optimally adapted individuals, and out of necessity, curiosity, or self-indulgence, we have invented technologies to venture into previously impenetrable domains, from the depths of the oceans to the depths of space.
Humans on the frontiers of exploration are tested to the limits of their lives. The Biology of Human Survival pinpoints critical factors that dictate life or death at the utmost reaches, including those places accessible to humans only with lifesupport technology. The book presents environmental physiology using modern, integrated concepts of stress, tolerance, and adaptation. Barriers to life in extreme environments, such as dehydration, starvation, and radiation, are described in separate chapters. Other chapters explain the problems unique to specific environments by examining the determinants of an individual's survival at extremes of cold, heat, altitude, or immersion. Key issues in these specialized settings are illustrated with examples of extreme hardship from great exploits that have attracted people's attention throughout history.