Senescence, the Last Half of Life

by G. Stanley Hall

Better hygienic methods, according to Fisher,[128] started with Pasteur, who said it was within the power of man to rid himself of every parasitic disease. Hygienists have followed this clue. The Roosevelt Conservation Committee in its report on national vitality and the summary of European life tables show that human life lengthened during the 17th and 18th centuries at the rate of only 4 years per century, while during the first three-quarters of the 19th it lengthened almost twice as fast and since that four times as fast, or about 17 years per century. If we could continue to increase life seventeen years a century, the world would soon be peopled with Methuselahs. We are witnessing a race between two tendencies, the reduction of the acute infections, such as typhoid, and an increase of the chronic or degenerative diseases, such as sclerosis, Bright’s disease, etc. The degenerative tendency appears more in evidence here than elsewhere. In Sweden the expectation of life increases at all ages. Even the nonagenarians have more years to live than did those of former days in the United States. We are freer from germs than our ancestors but our vital organs wear out sooner. And this degeneration of our bodies follows that of our habits. In England, where these diseases are not increasing, individual exercise out of doors probably has something to do with it. In Sweden individual hygiene is better cultivated than anywhere else in the world. It is the only land where public health includes private habits and touches the life of the people, especially through the school. The best statistics show that a large number of our young men and women suffer from diseases of heart, kidneys, lungs, and circulation, with impairment enough to consult a physician, that is, over half of our young men and women in active work and presumably selected for their work as fit, are found, although unaware of the fact themselves, to be in need of medical attention; while 37 per cent are on the road to impairment because of the use of too much alcohol, tobacco, etc. Now, a stitch in time saves nine. Thus the lesson to all of us is obvious.

I. M. Rubinow[129] says the problem of poverty among the old is connected with inability to find work because productive power has waned forever. American experience in tables of mortality shows that of 100 persons at the age of 20, 53 will reach 65; 12, 70; at which time the average expectation of life will be 8½ years. If we take 100 people at the age of 30, 53 will live to 65; 48 to 70. But this table was compiled half a century ago, although it is still used—to the great profit of insurance companies as expectation has greatly increased. Ten to fifteen years of life over sixty-five are assured to more than half all wage workers. In 1880 the percentage of persons 65 or over was 3.5; in 1890, 3.9; in 1900, 4.2; in 1910, 4.3. The number over 65 per 1000/15 increased from 54 to 60 in 1890, and to 63 in 1910. Employed males over 65 per 1000/15 constituted 50 in 1890; and in 1900, 47. Thus the production of old men is increased while the proportion of old men is declining. In 1880, of all old men over 65 years of age, 73.8 per cent were gainfully employed; in 1900, only 68.4 per cent. The total number of men over 65 in 1900 was 1,555,000. Thus economic progress in ten years meant an additional hundred thousand thrown out of employment. In agriculture, 6.1 per cent of the men employed are over 65; in the professions, 5.5 per cent; but in manufacture and mechanics, only 3.5 per cent; and in trade and transportation, 3 per cent. Thus old men are either thrown out or shifted to unskilled occupations. What does the “iron law” of the increase of old age dependency under a system of wage labor mean? It is wrong to seek the cause in exceptional misfortune or in psychological or ethical feeling. The author of “Old Age Dependencies in the United States” says after sixty men become dependent by easy stages—property, friends, relatives, and ambition go and only a few years of life remain, with death final. The wage-earner is swept from the class of hopeful, independent citizens into that of the helpless poor.

As to the population problem, Raymond Pearl has studied the ratio between births and deaths in France, Prussia, Bavaria, and England and Wales from 1913 to 1920[130] and finds that, in general, the birth ratios rose during the war—in England to the 100 per cent mark—and that immediately after the war was over the death-birth ratio began to drop rapidly in all countries. Vienna suffered perhaps more than any other city but made the best recovery, showing how promptly the growth of population tends to regulate itself back toward the normal after even so great a disturbance. Thus the war, which was the greatest depopulator since the epidemic of the Middle Ages, caused “only a momentary hesitation in the steady onward march of population growth.” If we take any given land area of fixed limits, there must necessarily be an upper limit to the number of people it can support, but this limit will be approached asymtotically and the most rapid rise will be midway between the upper and lower limit, namely, at that point where half the possible resources of subsistence have been drawn upon and utilized. The statistician must approach this problem as the astronomer does in calculating the complete orbit of a comet, that is, he must construct his curve from a limited number of specific data. If we study the curve of growth of population in this country, we find that we have long since passed the most rapid rate of increase. If we compare this with that of France, which is an old country and much nearer the upper limit than ours, which started near the lower asymtote only a century and a half ago; or compare it with that of Serbia, which is intermediate, all the statistics available conform with singular accuracy to the theoretic curve.

Professor Pearl concludes that this country has passed the point of most rapid increase, that this rate began to decline about April 1, 1914, when our population was 98,637,000, and that our upper limit will be reached about the year 2100, when the population will be 197,274,000 or nearly double what it is now, with about 66 persons per square mile. Our population will be then far less dense than in many other countries, but the latter are not self-supporting. He even estimates how many calories, vegetable and animal, each individual will require daily and compares this with the agricultural possibilities of the future. Such considerations lead him to stress the importance of birth control. This had long been practiced in France before the war, where the birth- and death-rate nearly balanced, so that industrial development simply raised the standard of living. Germany, on the other hand, encouraged the increase of her population by every means and her scheme was, when the pressure became too great, to facilitate the overflow of her surplus population elsewhere. “A stationary population where birth-rate and death-rate are made to balance is necessarily a population with a relative excess of persons in the higher age groups, not of much use as fighters, and a relative deficiency of persons in the lower age groups where the best fighters are. On the contrary, a people with a high birth-rate has a population with an excess of persons in the younger age groups.”

In his discussion of life tables Pearl starts with that of Glover based on the registration area of the United States in 1910. If we assume an original hundred thousand starting together at birth we note that at the beginning of the second year of life only 88,538 survive. In the next year 2446 drop out; the year following, 1062. At forty about 30,000 have passed away and the line descends with increasing rapidity until about eighty, when it drops more slowly till soon after the century mark all the original hundred thousand have passed away. Expectation of life is the mean or average number of persons surviving at a stated age. Pearl’s diagrams show that the expectation of life of those born in Breslau in the seventeenth century was very much lower than that of an individual born in the United States in 1910, the difference amounting to 18 years. At the age of ten it has sunk to 12; at twenty, to 10 years; at fifty, to 4. But the individual of eighty in Breslau in the seventeenth century could expect to live longer than the individual of the same age now in the United States. The same result is found if we compare United States tables now with those of England in the middle of the eighteenth century, where expectation was also less before and greater after eighty. Pearson’s study of Egyptian mummy cases two thousand years old shows that expectation there was far lower yet through all the early stages of life, although after seventy those who survived had a greatly increased expectation. Thus either man to-day is constitutionally fitter to survive or else he has made himself better conditions up to about the seventh decade. The reason why expectation increased after that period is because conditions were so unfavorable that all but the very most rugged succumbed earlier in life and the proportion of those who reached advanced age was far less than now. In Rome, during the first three or four centuries of the Christian era, the expectation was less yet until nearly sixty, after which it rose, and it is significant that expectation of life was far less under the conditions then prevailing for women than for men at all ages of life, which is the reverse of conditions now prevailing. In the Roman provinces, however, expectation was greater than in the Eternal City. In the Roman-African population, although there was greater mortality to about forty, expectation of life was superior after that age in the early part of the Christian era to what it now is.

In considering life tables that give the number of deaths occurring at each age, which give an S-shaped curve falling very rapidly before the end of the second year and reaching its highest subsequent point at seventy, Karl Pearson finds in this S-shaped curve five components which he typifies as five Deaths shooting with different weapons and with differing precision as the procession of human beings crosses the Bridge of Life. The first Death is a marksman of deadly aim and unremitting diligence who kills before as well as after birth. The second, who aims at childhood, has a very concentrated fire. The third, who shoots at youth, has not a very deadly or accurate weapon but one rather to be compared with a bow and arrow. The fire of the fourth marksman is slow, scattered, and not very destructive, as if from an old-fashioned blunderbus. The last Death plies the rifle, which none escape. Pearl justly criticises this conception because “no analysis of the deaths into natural divisions by causes or otherwise has yet been made such that the totals in the various groups would conform to these frequency curves.” Thus he holds that Pearson’s concept of the five deaths does not represent any biological reality but only demonstrates, as any other equally successful curve would do, that deaths do not occur chaotically but instead “in a regular manner capable of representation by mathematical function in respect of age.”

II

Let us glance briefly at the public and private provisions in different lands for the care of the aged, another large topic with a literature of its own. Here, too, we find great diversity of method and theory which it would be premature to attempt to harmonize. Indeed, so limited is our present knowledge of old age that the available data here also open rather than close most of the great questions about it, although we do seem to be at the beginning of a new era regarding this stage of life. If on the one hand, the length of life is increasing, as we have seen, on the other the intensity of modern life and industry is steadily reducing the age of maximal efficiency so that we feel the handicap of years earlier in life than formerly. The pressure of the advancing upon the retiring generation is ever-growing and if the manual laborer lives longer, he feels the impairment of age sooner. In fact, society is coming to a clearer realization, on the one hand, that youth must be served and conserved and, on the other, is just beginning to see that the same is true of old age.

Not only is the average length of human life increasing as civilization advances but so is the relative and absolute number of old people. Although under the harder conditions that once prevailed those who reached advanced years did so by inherent energy of constitution as the choicest products of natural selection (even though relatively fewer in numbers), it is fortunate that those who now attain 60, 70, 80, etc., are on the average far more comfortable, as well as more numerous than ever before. Not only is eyesight conserved, loss of teeth made good, and many of the ailments of the aged mitigated by modern medicine and hygiene, but by homes, pensions, etc., their lot is made far easier.

Youth tends to live in and for the present and middle life is too absorbing; while the decrepitude of old age seems so remote and its attainment so uncertain that the masses of mankind are still far too improvident of the future. It is somewhat as if our race had developed in tropical abundance where there was little need of providing food, clothing, and shelter, and had not adjusted even to a more northern climate, still less to the complexities of modern civilization and least of all to the increased chance of attaining old age with its infirmities. Still, great progress has been made in foresight and futures play an ever greater rôle in human calculations. The impulse to accumulate possessions itself always has a protensive factor and we cannot amass property without thinking of its safety and its use, and so we lay by, insure and bequeath.