Personal Habits
All experience, medical and lay, such as is embodied in Cornaro’s oft-quoted memoirs, Leonardus Lessius’s Hygiasticon or the right course of preserving life and health until extreme old age (1613), George Cheyne’s Essay of Health and Long Life (1724), Metchnikoff’s orthobiosis, and the Arabian proverb of the ninth century, quoted by Lacassagne,[75] that “the greatest dangers for an old man are a good cook and a young wife,” is in agreement as to the immense importance of strict moderation in indulging the appetites for the prolongation of life. The life histories of centenarians show that they have usually been small eaters, especially of meat. This is generally explained in terms of minimizing toxaemia, and it has been said that “man does not die, he kills himself” (Montaigne) and more graphically, if coarsely, that “he digs his grave with his teeth.” In some lower forms of life, such as the planarians (Child), partial starvation and the resulting reduction lead to rejuvenescence and so to the inhibition of the onset of senescence; hibernation has somewhat the same effect, though perhaps this might be partly explained as merely starvation during prolonged sleep. The question has often been raised whether partial starvation in man has any such positive influence, and unprofessional “cures” on these economical lines have not been unfashionable. It might indeed be argued that the Allen treatment of diabetes, in which starvation is followed by increased carbohydrate tolerance, depends on a certain degree of rejuvenescence. Cures consisting in purgation may act by partial starvation as well as by obviating toxaemia. After a period of starvation a normal person may become heavier than before, and his general health be improved. But in the present state of our knowledge and in the light of the dangers of starvation the further investigation in man of this problem is one that demands serious hesitation.
As to the bad influence of alcohol on longevity there can be no reasonable doubt. Alcohol is a protoplasmic poison causing degenerative changes in the cells and reducing the resistance to infection. A collective investigation undertaken by Sir Isambard Owen[76] showed that there were very few hard drinkers among the long-lived, and Sir George Humphry concluded that the characteristics of the aged included temperance; among 46 centenarians one, and among 73 men over 90 one confessed to taking too much occasionally, and out of 298 men between 80 and 90 years of age 45, or 15 per cent, were classified as taking much alcohol. That such exceptions occur is explicable by great inherent vitality. It has been said that “wine is the milk of old people,” but from his experience of the hygiene of the elderly Sir Hermann Weber was not in sympathy with this view, and he pointed out the weakness of the popular idea that the moderate enjoyment of alcohol was harmless; for so-called moderate drinking is in reality often immoderate indulgence for the individual, and most of us must have recognized from observation that long-continued though moderate use of alcohol is followed by premature deterioration. The proverb vinum lac veneris and the tendency that alcohol has to lead to incontinence and so to venereal infection may be borne in mind in considering its influence on longevity. As a medicine alcohol has its occasional use, and though it may be a food it is an expensive one.
Smoking among centenarians was specially investigated by Sir George Humphry, who found that among 19 male centenarians 8 smoked much, one a little, and 10 not at all; while out of 30 female centenarians 4 smoked much, 2 moderately or little, and 24 not at all. There is no doubt that with advancing years there is commonly a relative loss of tolerance for tobacco, so that unpleasant symptoms ranging from cardiac extra-systoles, through abdominal pain, to tobacco angina, may dictate discontinuance of the habit. But a large number of old people have smoked in earlier life though subsequently non-smokers. Personal tolerance to tobacco shows great variations, and there is no doubt that well-marked symptoms may be caused by tobacco. But that moderate smoking diminishes the chance of longevity has certainly not been proved. Much discussion has taken place as to the relation between smoking and arteriosclerosis; it is true that in animals nicotine in considerably larger doses than can be absorbed by smokers, damages the arteries, and Huchard and Lazarus were convinced that it caused arteriosclerosis. Sir Clifford Allbutt,[77] after quoting the various opinions, points out that if tobacco be a cause of arterial disease, it acts very slowly, for at 45 years of age, after a quarter of a century’s exposure, the smoker’s arteries are not distinguishable from those of the abstainer’s; and he mentions the arteriosclerosis of the ancient Egyptians and of women as incidents detracting from any argument that tobacco is an important cause of arterial disease.
A large proportion of the centenarians and persons over 80 years of age collected by Sir George Humphry obeyed the adage early to rise and early to bed, and I well remember that he used to lay stress on the factor of getting up directly one woke and so denying the flesh the luxury of further sleep. Whether going to bed early and getting up early is more than an index of a life otherwise spent in accordance with the late Sir Andrew Clark’s “laws of physiological righteousness” may be questioned.
Bodily Conformation.—Long-lived people are usually spare, obesity being rare, and, allowing for some shortening due to age, of a good average height (Humphry). It is interesting in this connexion to quote the conclusions arrived at by Robertson and Ray[78] from comparison of groups of long-lived and short-lived white mice in similar conditions. The long-lived were relatively stable, highly resistant to external disturbing factors, displaying subnormal variability and a more or less well-marked, but not invariable, tendency to early overgrowth and relative paucity of tissue accretion in late life; while the short-lived animals showed exactly the opposite features with a tendency to rapid increase of tissue in late life.
The importance of a healthy life with plenty of fresh air, sunshine, exercise, proper diet, and absence of worry hardly needs insistence. Leonard Williams[79] has epigrammatically summed up the hygiene of old age as “Fresh air, meagre fare, freedom from care.”
V
THE CAUSES OF SENESCENCE AND GENERAL ATROPHY: LIMITED VITALITY OF CELLS—INFLUENCE OF THE ENDOCRINE GLANDS—METCHNIKOFF’S PATHOLOGICAL EXPLANATION SENESCENCE AND CARCINOMA
The causation of old age is so complex that it is not possible to argue with any conviction that any one of the following explanations exclusively solves the problem satisfactorily.