THE AVERAGE MAN

Greymouth Evening Star, 18 June 1936, Page 4

THE AVERAGE MAN

AGE AND POPULATION

Pick up Dublin and Lotka’s recentlypublished “Length of Life” (Ronald) and you discover more about the average man. writes the science editor of the “New York Times.” Dr. Louis I. Dublin is third vice-president of the Metropolitan Life Insurance Company and Dr. Alfred J. Lotka is assistant statistician of the same company. Each is well-known —Dublin for his many contributions to magazines and his books on population, and Lotka for his “Physical Biology,” which broke new ground and which was recommended by the Library Association for the Institute of Intellectual Co-opera-tion of the League of Nations. Both Dublin, and Lotka, like other statisticians, have done much to acquaint us with the now familiar and agreeable fact that at birth the expectation of life for a man is 59.31 years. When a male child reaches the age of ten its further expectation is 55.3 years; at 21 it is 45.21 years. The expectation of life of women exceeds that of men by 3.52 years at birth and by somewhat lesser amounts in later years. Thirty years ago the picture was darker. Then the average length of human life (flic same thing as (he expectation of life at birth) was 46.07 years. In a hundred years the gain iias been of the order of 20 years.

Why the increase? Not one but several answers must be given. Dunlin and Lotka stress improved standards of living and advances in medical and sanitary science.

Especially valuable is the description of “Applications Io Population Problems,” which clearly follows the lines laid down by Lotka’s “Physical Biology.” Years ago Lotka showed that a population in which survival and reproduction follow a fixed age schedule ultimately increases at a definite rate different from that which may prevail at the moment. The existing and transitory age distribution which disturbs the balance between births and deaths gives place to a stable age distribution. Tire birth and death rate is then characteristic of the actual mortality and fertility. The principle was first, developed by Lotka and Dublin in a notable article published in 1925, now one of the classics of population studies. What does it. mean? That the present excess of births over deaths is misleading. Actually our prevailing rate of reproduction is insufficient in the long run to balance our mortality despite the increased expectation of life.