Life and Health
Periods and Conditions of Life
Physiologists divide Human Life into four periods, the embryonic, immature, reproductive, and sterile ages: the first terminating at birth; the second at puberty, which is achieved at 15; the third at 45, after which few mothers have children; and the last at 100 and upwards.
Individual life exists on such conditions that it may at any moment cease; and the vital tenure varies not only with every change of external circumstances, but by natural laws at every year of age. It is most insecure in infancy and old age. At the age of puberty—before the period when the growth of the body is most rapid—before the age of its greatest strength—before the age of greatest intellectual power—it is less assailable by death. The chance of living through a given year increases from birth to the age of 14 or 15; it decreases to the age of 55-8 at a slightly accelerating rate; after which the vitality declines at a much more rapid rate.