Senescence, the Last Half of Life

by G. Stanley Hall

The Kamerlengo strikes the Pope on the forehead three times with a silver hammer and calls his name and, if he does not answer, says, “The Pope is really dead.” This is because hearing is supposed to be the last sense to die. But often after death the muscles contract spontaneously, even enough to move the body and this has made survivors believe their friends were alive. The muscles respond to electrical stimuli for hours. The pupil of beheaded people contracts to light. In Charlotte Corday’s head the eyes opened. Dr. Rousseau saw a case in which the heart occasionally beat twenty-nine hours after decapitation. Generally death proceeds from the heart and its last beat marks the entrance of death. Respiration, too, or the last breath is often the mark of death because the carbon dioxide is not removed; hence we say life is in the blood. Everyone at times wonders not only when he will die but how. And it is hard to live so as to avoid pathological death.

A French nobleman, François de Civille, in the time of Karl IX, appended to his monument the inscription: “Thrice dead, thrice buried, and by the grace of God, thrice revived.” The riddle meant that he woke first from his mother’s body at birth and twice in war was thought dead and placed among the dead. But the absence of personal consciousness is very unreliable because after long periods of lethargy many have rather suddenly revived. There never was a doctor present at an exhumation of a living man. Being buried alive is really a ghost that has no justification in civilized lands. This has nothing to do, of course, with simulation. Karl V simulated death in order to enjoy the spectacle of his funeral, as Juliet allowed herself to be buried. By contraction of the muscles of the neck and deep respiration the heart can be checked and the physiologist, Weber, nearly lost his life thus. Dr. Gosch tells of a Colonel Townsend who in the presence of Prof. Cheyne stopped his heart and breathing, the latter tested by a mirror, for half an hour until they were all convinced he was dead. But then he gradually came to, though he died eight hours later.

Herter and Rovighi tested lactic acid and its effects on fermentation of the large intestine and found negative results, so that we do not have an arcanum against death or old age in this sense, although insufficient excretion of toxins has much to do with it.

In his illuminating articles Professor Raymond Pearl, after showing the novelty of natural death and how even somatic cells now seem possibly immortal if separated from the metazoan body and that heredity is a prime determinant of the length of the span of life, says we must know more of the vagaries of germ plasm before society should assume to control it, although such control sooner or later will be necessary. The death rates for the four diseases that public health and sanitary activities have been most successful in treating, namely, (1) tuberculosis of the lungs, (2) typhoid fever, (3) diphtheria and croup, (4) dysentery, have been materially reduced in the last nineteen years. But if we compare four other causes of death, (1) bronchitis, (2) paralysis, (3) purulent infection and septicemia, (4) softening of the brain, on which health and sanitation have had little effect, it is found that the rate of mortality from these troubles has declined just as much, and probably a little more, in the same period of time, although the numbers in the latter group are far less. “Hence the declining death rate in and of itself does not mark the successful result of human effort.”

Recognizing the fact that the essential cells in our body are inherently capable under proper conditions of living indefinitely, the problem that confronts us is whether environment or heredity has most to do in determining the actual length of life. Pearl[163] concludes that the death rate of the earliest period of life is selective, eliminating the weak and leaving the strong, and that inheritance is “one of the strongest elements, if not indeed the dominating factor, in determining the duration of life of human beings.”

The duration of life in animals also depends on the total amount of metabolic activity or work and it has been proven that rats, at least, live longer under conditions so controlled that their activity is lessened, so that the greater the total work done or total energy output, the shorter is the duration of life and vice versa, work accelerating the aging process somewhat as rise of temperature does. Pearl says: “The manner in which the environmental forces (of sublethal intensity of course) chiefly act in determining the duration of life appears to be chiefly by changing the rate of metabolism in the individual. Furthermore, one would suggest, on this view, that what heredity does in relation to duration of life is chiefly to determine within fairly narrow limits the total energy output which the individual exhibits in its lifetime.” The duration of life of an animal stands in inverse relation to the total amount of its metabolic activity or, put in other words, to the work in the sense of theoretical mechanics that it as a machine does during its life. Or, to put it in another way, if the total activity of a unit of time is increased by some means other than increased temperature, the same result appears as if the increased activity is caused by increased temperature. Pearl thinks that Steinach’s experiments on the sexual glands, whatever their results for rejuvenation, do not prove “any really significant lengthening of the life span.” Nor does he think that Robertson’s experiments with tethelin from the pituitary gland, whatever its effects upon growth, show that it materially increases the length of life to a degree that has much significance statistically, so that inheritance remains a prime determinant of longevity.

We are all born in one way but die in many. By international agreement a mortality code has been developed with fourteen general classes comprising 180 distinct units. Pearl would supplement this very unsatisfactory classification by the following: (1) circulatory system and blood-forming organs, (2) respiratory system, (3) primary and secondary sex organs, (4) kidney and related excretory organs, (5) skeletal and muscular system, (6) alimentary tract and associate organs concerned with metabolism, (7) nervous system and sense organs, (8) skin, (9) endocrinal system, (10) all other causes. This would show organological breakdown rather than pathological causation. The breakdown of the respiratory system is the chief cause of death, and next comes that of the alimentary tract; these together constitute half the deaths biologically classifiable. Next come troubles with the blood and circulation. We may conceive these as three successive defense lines, and it is against the first two of these that better health and hygiene have been chiefly directed, having been most successful with the respiratory system. Child-welfare, both pre- and post-natal, is by all odds the most hopeful direction of public-health activities. Pearl’s very important studies here confirm the conclusions others have reached, that early pubertal years show the lowest mortality rate, and he traces in detail for each age of life the mortality curves for each of the chief groups of disease.

Very interesting are his conclusions touching the embryological basis of mortality in which he attempts to trace the causes of death back to the three primitive tissue elements, concluding that about 57 per cent of biologically classifiable deaths result from the breakdown or failure to function of organs arising from the endoderm, 8 to 13 per cent from those that spring from the ectoderm, while the remaining 30 to 35 per cent are of mesodermic origin. The ectoderm has been most widely differentiated from its primitive condition, as best illustrated by the central nervous system, the endoderm least differentiated, while the mesoderm is intermediate in this respect. Now, degrees of differentiation imply adaptation to the environment and the endoderm, which is least differentiated, is least able to meet vicissitudes. “Evolutionally speaking, it is a very old-fashioned and out-of-date ancestral relic which causes man an infinity of troubles. Practically all public-health activities have been directed toward overcoming the difficulties which arise because man carries about this antediluvian sort of endoderm.” Prior to the age of sixty the breakdown of organs of endodermic origin causes most deaths; next come breakdowns with organs of mesodermic origin, and lastly those of ectodermic origin. The rate for all these germ layers is relatively high in infancy, dropping to a low point in early youth. In infancy the chief mortality is due to endodermic defect; from about the age of 12 on, to faults of ectodermic, and after about 22 to those of mesodermic origin. The death-rate curve rises at a practically constant rate to extreme old age. From about 60 to the end of life deaths from the breakdown of organs of mesodermic origin lead. The heart generally outwears the lungs and the brain outwears both because evolution is a purely mechanical process instead of being an intelligent one. “It is conceivable that an omnipotent person could have made a much better machine as a whole than the human body which evolution has produced. He would presumably have made an endoderm with as good resisting and wearing qualities as a mesoderm or ectoderm. Evolution by the haphazard process of trial and error which we call natural selection makes each part only just good enough to get by.” All this, the author believes, only strengthens the evidence that the most important part in longevity is played by innate constitutional biological factors.

This view so commonly held, that heredity is the chief factor in longevity is doubtless correct in general. But it is fatalistic and directly tends to lessen the confidence of hygienists and physicians in the efficacy of all their methods of prolonging life in the aged. There is, we think, good reason to believe that there is a great and now rapidly growing number of exceptions to this so-called law, cases in which by conformity to right rules of living, age has been increased many years beyond that which our forbears attained. Indeed, the very fact of the gradual prolongation of life shows that the hereditary predisposition to die at a certain age can be, to a great extent, overcome. The psychological effect of this dogma of the prepotence of heredity in determining the length of life is itself not only depressing but may readily become, as psychologists can best understand, a dangerous lethal agent with the old and cause those who have reached the span of years at which their forbears died to succumb to their troubles with less resistance. Indeed, it is one of the chief purposes of this volume to show that the old-age problem is not merely economic, philanthropic, social, or even medical, but also, when all is said and done, perhaps chiefly psychological and that the future welfare of the race depends upon the development of an old age due not chiefly to heredity but to better knowledge and control of the conditions of this state of life.

Senescence is, in no small degree, a state of mind as well as a state of body, and the study of it as such has been so far strangely neglected but is now in order. Even doctors who have told us most about it have made few intensive investigations of its nature and there are very few gerontologists; while the alienists who have described the senile psyche have done so only in general terms that add but little to what is obvious to common experience and observation. None have sought to ascertain empirically from intelligent old people capable of telling how they think and feel about their stage in life, or to determine how far their attitude toward it was indigenous and how far it was really due to the acceptance of current traditions that have come down to us from a remote past and that no longer fit present conditions. How this old tradition still influences even physicians may best be shown by a few instances that have come under my own observation. A friend of 73 fell sick of pneumonia which soon involved both lungs. The excellent family doctor had him removed to a hospital where expert care could be added to his own. Soon all hope of his recovery was abandoned and for a week friends who called or telephoned were told that nothing more could be done and the end was certain and might be expected any time. “He is 73, you know,” the doctor said. To-day he is well and daily active in the very large concern he created. The father of an intimate friend at the age of 69 fell ill from a complication of disorders the family doctor diagnosed as old age and telegraphed his son to hasten home from a distant city if he would see him alive. Upon his arrival, on the morning of the 70th birthday, he found him half comatose and convinced that this day would be his last; but he was cheered up, diverted, partook of a stimulated eggnog, his first food for two days; and when he awoke just past midnight and realized that he had entered upon another decade, revived, made a slow but surprising recovery, and enjoyed not only a comfortable but a very active life for nine years. He could not, however, quite bring his mind to enter the ninth decennium. Strangely enough, my friend’s mother, whom I had also known all my life, two years later passed through almost the same experience. He was called to her deathbed, reaching her three days after all hope had been abandoned. But she recovered and was nearly as well as before, and lived seven years. A friend of mine retired from a college chair at 74 and was told that he was worn out, had several grave symptoms, and must drop work and go South. “You should be satisfied,” his physician told him, “with four years beyond the allotted three score and ten.” But he had unfinished tasks, believed them to be life-preservers, and now at 82 is still engaged upon them. A vigorous old lady of 87 has thrice been given up by her physician within the decade. Are doctors a little falsetto in their treatment of the aged?