ABSTRACT
The human body faces risks that are multiple, varied, and unpredictable. In multiple, there are many sources of potential injury. In varied, the body is vulnerable to many types of damage. In unpredictable, the body cannot know which disturbances it will encounter and when. The body apparently values growth over defense. Defense alone does not ensure survival; organisms must develop effective growth mechanisms if there is to be anything left to defend. Life must go on after the battle is won. Many defensive measures fail to reach levels that might, if viewed in isolation, be considered optimal. Redundancy is essential to defense based on diversity. Safety would not be promoted if each structure were specialized and separate, because that would merely increase the number of irreplaceable parts. The lack of total anticipation does not leave the body defenseless, however, because the human organism has developed a sophisticated set of resilient defenses to supplement its anticipatory mechanisms.
