The paper is concerned with some evolutionary aspects of aging. Old age diseases are considered as a concrete mechanism of maintenance of the species' lifespan within limits intended by evolution. The relationship between reproduction, aging, and diseases based on the evolutionary conception proposed by Williams is discussed. According to the author's hypothesis, the human population consists of the two subpopulations which differ by the constitutional type of hormonal regulation and reproduction potential; the constitutional type of hormonal regulation exerts a considerable effect of the aging rate, morbidity, and longevity.