The struggle between organism and environment is nature’s paradigm, but this is often underplayed in human endeavors. We consider ourselves separate from other animals because we adapt to new environments, in part, by rational action. Thus, the book’s underlying theme is the role of behavior in adaptation, emphasizing circumstances in which human technology will forever change the environment, such as after a nuclear war or during colonization of space. Once the subtle interplay of environment with the body’s responses and the individual’s behavior is grasped, a new window opens onto human survival. [p. viii]
The debate over human evolution is beyond the scope of the book, which deals with the individual, for whom the outcome of environmental stress can be reduced to tolerance and adaptation or death. These outcomes, however, have important ramifications for the long-term survival of humans both on this planet and elsewhere in the solar system. Thus, understanding how individuals adapt to the environment is a step on the road to discovering how the physical world shapes human biology.[p. xix]
The mechanism of dehydration and the body’s responses, 47
Dehydration and heat tolerance, 49
Mammalian homeothermy, 63
Humans as tropical primates, 64
Heat acclimatization and physical fitness, 71
Death by heatstroke, 76
The effects of extreme cold on the extremities, 89
Settings for systemic hypothermia, 90
The physiology of hypothermia, 92
Life in an oxidizing atmosphere, 129 Biological oxidations and oxygen toxicity, 132 Antioxidant defenses and the oxidant–antioxidant balance, 135 The free radical theory of aging, 136