Principles of Mammalian Aging

It is entirely appropriate that Prentice-Hall has included Dr. Kohn's book in their Series on Developmental Biology. Aging begins at the time of conception and only culminates with the overt decline we call senescence. Indeed, some may cavil that aging has already begun in the germ plasm prior to zygote formation, but in any case, the union of sperm and ovum triggers a fresh program: in man, threescore and ten, and in other species, a lifespan as distinct as gross body morphology. Finally, entropy, the inexorable tendency for all systems to reach maximum disorder, takes its toll. Indeed, the thermodynamic adage, "entropy is time's arrow," is remarkably apropos of the aging process. Implicit in books of this kind is the understanding that omissions will occur. Material will either escape the search of literature or be intentionally rejected to promote succinctness. Consequently, it is important to guide the reader to cogent