ECONOMIC ASPECT OF LENGTHENING HUMAN LIFE BY Prof. IRVING FISHER of Yale University President of the Committee of One Hundred on National Health Address delivered before ASSOCIATION OF LIFE INSURANCE PRESENTS New York, February 5, 1909 V/ SAN DtEGO' I ECONOMIC ASPECT OF LENGTHENING HUMAN LIFE. BY PROFESSOR IRVING FISHER OF YALE UNIVERSITY, President of the Committee of One Hundred on National Health. Concerted action by life insurance companies to lengthen human life would mark, I believe, one of the greatest steps, if not the great- est step, ever yet taken toward the improvement of human longevity. The nearest analogy is perhaps to be found in the work of fire insurance companies in reducing the number of fires. But it is a general truth that the best success of any movement is found only when, in a sense, it reaches the commercial stage in other words, when it is made to pay in some tangible way. Philanthropy is keen to lead the way to reform, but becomes a broken reed if depended upon for its support continuously or on a large scale. The insurance men whom I have consulted as to whether it would pay to engage in the saving of lives have been unanimously affirmative in their answers. So obvious does this seem that the question arises, why have insurance companies never attempted it before ? There seem to be three explanations : First, the continuance, until recently, of the tradition that human mortality follows a nearly invariable law, and a law which can not be appreciably affected by any act of man. Second, after it became known to experts that human life is greatly extensible through public and private hygiene, this knowl- edge was possessed by so few, that the general public, and even the rank and file of the medical profession, remained of the contrary belief, and the inertia of their conservative opinion prevailed. Third, it seemed too large a task for any one company to pro- long life for the whole country, and there seemed no way to pro- long the lives of its own policy-holders alone, so long as unsanitary conditions prevailed throughout the communities in which these policy-holders lived, while finally there seemed no way of bringing 1 the various life insurance interests to agree on concerted action. It seems now, however, that the time has arrived when all three of these objections can be removed. I assume that before this- audience there is no need of presenting evidence or arguments to prove that human life may be lengthened by hygienic measures, and shall therefore merely run over very briefly the most salient and general facts, as introductory to the formulation of a practical plan of action. It has long been known that there is no iron law of mortality, but that mortality depends on the hygienic state of the community. Baines, in a recent paper in the Journal of the Royal Statistical Society, has calculated that the average duration of life in India is only twenty-three years for males and twenty-four years for females, or less than half the life span in the advanced countries of Europe. The estimates of Finkelnburg show that in Europe human life has probably doubled in the last 350 years. More recent and more reliable figures show that life is lengthening to-day more rapidly than ever. If we take life tables for different periods for England, France, Prussia, Denmark, Sweden, and Massachusetts, we find that human life lengthened during the Seventeenth and Eighteenth Centuries at the rate of four years per century; that during the first three-quarters of the Nineteenth Century it lengthened at the rate of about nine years per century; that at present it is lengthening in Europe generally at the rate of seventeen years per century, and in Prussia (which is perhaps the home of preventive medicine) at the rate of 27 years per century. For this country the rate can only be judged from the statistics for Massa- chusetts, which show that life is lengthening by about fourteen years per century, or approximately half of the Prussian rate. These rates may not continue in the future, but the opinion of our best authorities on longevity, such as Ray Lankester and Metch- nikoff, is that there is still great room for improvement especially after middle life. Hitherto almost all the improvement has applied to ages before fifty and only the most recent figures show any tendency toward improvement beyond that age. It is significant that backward India in spite of the enormous room for improve- ment shows during twenty years no rate of improvement whatever. The statistics of insured lives show that the insured poor, as represented by the Industrial Companies, have a mortality from fifty to eighty per cent, higher than the insured rich or well-to-do, as represented in the ordinary insurance companies. The unsani- tary districts of Glasgow and Paris show a mortality more than double that of the sanitary districts, while cities in general show a much higher mortality than the open country. A fall of the death rate always promptly follows sanitation. Colonel Gorgas cut the death rate in Havana in two, bringing it down to between 20 and 24 per 1000. The New York death rate responded at once to Colonel Waring's clean streets, and that of Rochester to Dr. Goler's milk crusade. And now it is announced that the death rate of New York is 16.5, the lowest on record a result, in all human probability due to the hygienic work of Dr. Darlington, the efficient health officer, Mr. Nathan Straus, the milk reformer, and the public agitation for health prosecuted by the New York Times, the Journal, and other media, allied with the health work of the Committee of One Hundred on National Health, the Tuberculosis Association and Committees, and other organizations. These and other facts and the mass of detailed figures which they represent show conclusively that human life is long or short precisely according to the hygienic conditions under which it is lived ; that human life can be prolonged as these hygienic conditions are improved, and that there is still enormous room for improve- ment. Farr, twenty years ago, in his masterly work on Vital Statistics, stated that any community could attain an average dura- tion of life equal to that in the so-called "healthy districts" of England where the average duration of life was then fifty-one years. To bring all England up to this level would at that time mean a lengthening of life by one-fifth, or twenty per cent. A report which I have recently prepared for the Conservation Commission, based on data contributed from acknowledged Ameri- can authorities, shows that human life in America could, by the adoption of hygienic reforms already known and entirely practic- able, be lengthened by over one-third that is, over fifteen years. This calculation has been made very conservatively and is prob- ably several years inside the truth. The statistics and estimates on which it is based have been taken from published sources, as well as contributed by some score of American authorities medical, actuarial, and hygienic. A safe minimum estimate was made- of the degree of pre- ventability of the deaths from each of the ninety principal causes of death in the United States. For instance, for typhoid fever, experience in Lawrence, Massachusetts, has shown that the intro- duction of a public water filter reduced the typhoid mortality by eighty per cent. In Munich the cleaning of cesspools and other hygienic measures reduced the mortality from typhoid by ninety- seven per cent. On the basis of these and other facts, it was con- servatively estimated that eighty-five per cent, of the deaths now occurring from typhoid fever in the United States could be easily prevented. Professor Sedgwick recently announced the truth of Hazen's theorem that for each life saved from typhoid, two or three lives are saved from other diseases. This cumulative effect, however, was not taken into account in the calculations, nor was account taken of the constant advance being made in preventive medicine. For these and other reasons, the calculated estimate of the improvability of human life is regarded as ultra-conservative. Tuberculosis is known to be preventable. In my table, it is entered as only seventy-five per cent, preventable; pneumonia as forty-five per cent, preventable; typhoid as eighty-five per cent.; diphtheria, seventy per cent. These conservative figures are among the highest allowed. Many diseases, such as cancer, are recorded in the table as zero per cent, preventable, although the best expert opinion would allow some degree of preventability, if prevention begins early enough in life. On the basis of these ratios of preventability, or rather post- ponability of death, has been computed the possible extension of the average human life