Fig. 3.—John Haviland, M.D., F.R.C.P. Professor of Anatomy 1814–17, Regius Professor of Physic in the University of Cambridge, 1817–51; Linacre Lecturer, 1817–22 and 1826–47.
From a drawing done in 1851 by Wageman. For this I am indebted to H. A. Haviland, M.B.
The somewhat neglected subject of Old Age has a very pertinent connexion with the most essential aim of medicine as a whole, namely, the prevention of disease. For when the ideal of the prophylaxis of infection and of other causes of morbid action is attained, a healthy old age and physiological death without attendant disabilities and horrors should be the common lot of man instead of being somewhat exceptional in the case of the first and extremely rare as regards the final act. The conditions favouring longevity and mens sana in corpore sano are those necessary to make the future of the human race a happy and beneficent prospect instead of a problem inspiring doubt if not pessimism; or in Descartes’ words, “we might be free of an infinity of maladies both of body and mind, and even of the infirmities of old age, if we had sufficient knowledges of their causes and remedies.” But in addition to this broad ground of interest there are reasons why a discussion of this subject has a special claim for consideration in Cambridge. The objects of a University include the preparation of its alumni for life in its fullest and best sense, and from this point of view the permanent ornaments of the community ever set an unobtrusive example of the way to deserve and enjoy a healthy, happy, and useful old age, namely, activity of mind and body and moderation in all things; such a life of 75 years (that of Professor G. D. Liveing) in the University must be in your recollection as described by the Public Orator as tam honesta, tam utilis. Further, as in private duty bound, I cannot forget that Sir George Humphry, to whom this great medical school owes so much, greatly interested himself in the subject of old age and published the results of an elaborate collective investigation. Lastly, it is desirable that the problems of old age should be attacked by young and active minds in the laboratories of the University and not left as a semi-personal field of enquiry and observation to those whose “way of life is fall’n into the sere, the yellow leaf,” and who hear old age’s stealthy footsteps catching them up in the race; for in the past most of the writers on geriatrics have written with at least some personal qualification and interest, such as Cornaro, Sir John Sinclair, Sir Anthony Carlisle, Charcot, Sir George Humphry, Sir Hermann Weber, R. Saundby, Metchnikoff, Stanley Hall. As an exception, however, we may point to Dr. John Smith,[8] who, in his thirty-fifth year, was the author of King Solomon’s Portraicture of Old Age, which paraphrases in 266 pages the “six former” verses of the 12th Chapter of Ecclesiastes containing 205 words.
II
DURATION OF LIFE
In the protozoa and some other lowly forms of animal life multiplication by binary fission occurs indefinitely, so that one organism is succeeded by two, and as there is no vestige of a corpse, as Weissmann expressed it, the organism is immortal. Maupas’s[9] investigations indicated that without occasional conjugation of two individual protozoa and the resulting rejuvenation the organisms undergo senile degeneration and die; but Woodruff[10] has shown by observations extending over 13½ years that Paramoecium, and so presumably infusoria in general, can multiply indefinitely in favourable conditions without conjugation, though periodically an internal reorganization (endomixis[11]) of the individual takes place. It seems not improbable that endomixis provides the rejuvenation otherwise resulting from conjugation. C. M. Child[12] brings forward reasons for modification of the explanation that death is escaped simply by division; he shows that in certain circumstances senescence occurs in the protozoa as it does in the higher animals, but that death is avoided by the rejuvenescence in each process of reproduction, reconstitution occurring and new organs being formed in the place of the old. In other words, all organisms from the protozoa to man undergo senescence and die unless rejuvenescence intervenes; this compensation holds good in the lower forms and death may never occur; but in the higher forms rejuvenescence is so much restricted by the evolutionary increase in the physiological stability of the protoplasmic substratum and the resulting higher degree of individuation that senescence is much more continuous and death is inevitable. It is the penalty for high individuation, and is the result of conditions and processes that have produced the complicated mechanism of the higher animals and man. While holding out the faint hope that the advance of knowledge and of experimental technique may make it possible at some future time to bring about a greater rejuvenescence and retardation of senescence in man and the higher animals, Child points out that the present condition of their protoplasmic substratum is the result of millions of years of evolutionary equilibration, and that this task must therefore be one of extreme difficulty.
Modern biologists such as Driesch, E. Schultz, Child, Steinach, and Julian S. Huxley, to the last of whom I am personally much in debt, have indeed shown that experimentally the life cycle and growth, which are so closely correlated, may be modified dramatically by various methods. By starvation planarian flat worms become smaller and their life cycle is reversed by the process variously called dedifferentiation, reduction, or involution, whereby their structure becomes simpler; similar retrogressive changes have been produced in the social ascidians, Clavellina and Perophora (J. S. Huxley[13]), this process of dedifferentiation or reversible differentiation being the primitive reaction of organisms to unfavourable circumstances. By alternate feeding and starvation Child has kept planarian flat worms at the same size while controls passed through nineteen generations, thus showing that the life of cells is not a matter of time but of metabolism. In the higher animals the conditions are of course more complex on account of the self-regulating mechanisms, especially the ductless glands. But by disturbing the endocrine balance experimental biology has produced some remarkable results: by feeding white mice with tethelin (a phospholipin obtained from the anterior lobe of the pituitary) Robertson and Ray[14] found that epithelial proliferation was accelerated, though increase in weight of the animals was retarded, and that the duration of life was prolonged. Drummond and Cannan,[15] however, failed to confirm these results, and feeding with the anterior lobe of the pituitary has given rise to very contradictory reports; acceleration (Clark, Robertson, Goetsch), retardation (Pearl, Wulzen), and no effect (Gudernatsch, Lewis and Miller, Hoskins, Sisson and Broyles[16]) have been described. Steinach’s rejuvenation of senile rats by ligature of the vas deferens, which is followed by increase in the interstitial cells of the testis and definite prolongation of life, will be referred to later (vide p. 76). The retardation of growth due to a diet deficient in vitamins, first proved by Gowland Hopkins[17] in 1912, may be maintained for long periods, but when the diet is appropriately altered growth is resumed and proceeds to the full standard (Osborne and Mendel[18]); it remains to be proved that the total duration of life can thus be prolonged. Though every living species of animal may in normal circumstances have its allotted span of life, this is so subject to accidents and modifications by external influences that the average duration of existence, especially in the long-lived species, does not represent the natural term of years. Thus the expectation of life at birth in England and Wales is 51·5 years for males and 55·35 years for females, as contrasted with the ideal physiological duration of life for 100 years. Violent death in one form or another—traumatic or infective—is so much the rule that the occurrence of natural death in the animal kingdom has been questioned, just as de Candolle denied the natural death of trees and ascribed it to injury or disease. Metchnikoff,[19] who paid special attention to this question, described natural death in the Ephemerids, day-flies, the imagines of which are incapable of feeding and after an hour or two of “aerial life devoted to love” die, their ova falling into the water; Sir Ray Lankester accepts the view that they are “wound up” for a few hours only of life, but according to Child death is probably due to starvation. In man natural death from old age—a physiological ending—is very rare, much less frequent indeed than death certificates and ordinary parlance would suggest; for in such cases there is very commonly some latent disease, such as pneumonia, which just turns the scale in the trembling balance. Montaigne warns us “what an idle conceit it is to expect to die of a decay of strength, which is the last of the effects of the extremest age, and to propose to ourselves no shorter lease of life than that, considering that it is a kind of death of all others the most rare and hardly ever seen.” While it must be admitted that this still holds good, it is a stimulus to our efforts to render it no longer true.
The length of days ascribed to Methuselah (969), Adam (930 or, if the “conceit urged by learned men,” as Sir Thomas Browne[20] says, that he was 50 or 60 years old when called into being be accepted, 980 years), Seth (912), has aroused attempts at explanation on the basis of a difference in chronology. The suggestion that the “years” were lunar and not solar, in other words containing 30 instead of 365 days, was controverted at length by Eugenius Philalethes[21] (not Thomas, twin of Henry Vaughan “the Silurist”) as too radical, for on this interpretation some of the patriarchs would have become fathers of children before they were ten years old. Long ago, Hensler, following Justin, put forward the view that the year consisted of but three months up to the time of Abraham, when it was extended to eight months until the era of Joseph, after which it contained our full complement of twelve months. This explanation was supported by Hufeland[22] on the ground that some eastern nations still reckoned three months to the year. Adopting this explanation Methuselah’s age would be cut down to 243 years.
The Psalmist’s threescore years and ten and its sorrowful extension to fourscore are so often exceeded by human beings who appear normal that the possibility of a far longer existence has often been raised. John Sterne or Stearne (1624–69) who, though founder of the Irish College of Physicians, was, according to Mahaffy,[23] more of a theologian than a physician, believed that there was no reason why men should not live as long as the patriarchs before the Flood; but he also argued that these patriarchal ages must have been exceptional, for had all the human beings between the Creation and the Flood, a period of more than 1400 years, lived to an average breeding age of 400 years and begun, as did the patriarchs, to beget children at the rate of one male every three years, the population of the earth could not have found standing room on its surface; his colleague in Trinity College, Dublin, Miles Symner, Professor of Mathematics, provided him with a calculation showing that there would have been less than one cubic foot available for each individual. This seems to be echoed in a slightly different connexion by Weissmann’s conception of natural death as due to natural selection and as an adaptation for the good of the species, the degenerated organisms being no longer fertile or useful, an hypothesis hardly necessary, as Metchnikoff points out, when degeneration which is the prelude to dissolution has appeared. Roger Bacon[24] stating that man, originally immortal and after the Fall able to live for a thousand years, had his life gradually abbreviated by corruption of his own making, believed that it should be possible by taking care as to regimen to prolong life for a hundred or more years than the common duration. Since the time of Aristotle the vital cycle has been thought to be a multiple of the period of growth. Francis Lord Bacon considered that animals in general should live eight times as long as they take to come to maturity, and Hufeland,[25] adopting this principle, and regarding 25 years as the termination of adolescence, concluded that man’s natural span should be 200 years. Buffon took 14 years as the age of puberty, and multiplying it by 7 decided that human life should naturally be 100 years. Assuming that union of the epiphyses of the long bones marked the time when growth was finally completed, Flourens[26] calculated that throughout the animal kingdom life was five times as long, and that as in man the epiphyses united at 20 or 21 years of age the span of human life should be 100 years.