CORRESPONDENCE.
COMPARATIVE LONGEVITY AND GREATNESS.
Whether or not great men are favored by an increase of years above those allotted to more ordinary mortals has long been a question of interest, and has acquired a special importance in connection with the study of the natural history of men of genius, and the discussions of the possible relation of greatness to degeneracy and to insanity. Questions of this type can only be decided on the basis of extensive and carefully collected data, which unfortunately it is difficult and at times impossible to collect or to find. It is therefore natural that such evidence as seems to exist and to carry with it some degree of logical force should be brought forward in proof of a claim which on general principles is both pleasing and plausible. Of this type is the problem of the relation between longevity and greatness, and of this type is the evidence now and then brought forward to substantiate the belief that great men are, as regards longevity, an unusually favored class.
The most recent presentation of the topic (by Mr. Thayer in the Forum, February, 1900) collects a list of some five hundred prominent men and women of the nineteenth century and finds that these persons lived on an average sixty-eight years and eight months; that is, nearly thirty years longer than the population as a whole. And on the basis of this conclusion the writer combats the notion that nineteenth-century men of genius or of eminence exhibit signs of degeneracy, because longevity and the ability to do sustained work for a large number of years is in itself a sign of unusual vitality and vigor. As these conclusions are apt to be extensively quoted, and as they seem to me founded upon a serious fallacy, I shall attempt to present as simply as possible the nature of the desired evidence which alone could prove that great men are longer lived than others, and to show that the evidence thus far presented is inadequate to support the conclusion which has been drawn. Mr. Thayer is not the first one to present the average age at death of a number of eminent persons as evidence of unusual longevity. In an article which was reprinted in the Popular Science Monthly for May, 1884, the average age at death of 1,741 astronomers was given, and found to be sixty-four years and three months; and on the basis of this fact the author claimed that astronomers enjoyed unusual longevity. In a brief contribution published in Science, October 1, 1886 (and republished in Nature, November 4, 1886), I called attention to the fallacy inherent in such conclusions, and also presented some new contributions to the question of the longevity of great men. The materials of that article I shall utilize in the present discussion.
To reach the kernel of the matter at once, the reader must note that the fallacy consists in neglecting to consider that in dealing with astronomers or with great men, or with persons of eminence of the nineteenth century, one is dealing with a group which is already carefully selected, and the selection of which inevitably involves the attainment of a certain age. The result is that we are not dealing with average persons as regards longevity, but with persons who in the very nature of things have already reached a certain period of maturity. No one can become a poet, or a novelist, or a painter, or a philosopher, or a commander or a statesman unless he lives at least a sufficient number of years to acquire the development of an adult, and to have the opportunity of developing his abilities and distinguishing himself. If great men were great from their infancy, and if we had the means of ascertaining this fact, then, and only then, would the method used be correct.
It is ordinarily stated that the average duration of life is somewhere between thirty-three and forty years, and Mr. Thayer considers that in the present century it has moved forward towards the latter figure. What this means is that if we were to keep a record of the age at death of all Americans who are to be born within the first ten years of the coming century, we should find that their average age at death would be some thirty odd years. But this number can by no means be used as a standard with which to compare the average age at death of men of distinction, or indeed of any other class of men selected according to a standard which involves on their part the attainment of mature years. If we were investigating the longevity of twins, or of persons with supernumerary toes, or indeed of persons possessing any quality which one could detect in new-born infants, and if we could determine the average life-period of this class of persons and find that it markedly exceeded the average of the entire community, we should be entitled to conclude that twins, or persons who have supernumerary toes, are blessed with a greater longevity than the average man. But so long as men who are to acquire distinction bear no traces upon them of this power until they exhibit their powers and actually gain distinction, it is obvious that we are concerned with their longevity only from that moment when they have entered, or have become promising candidates for that class of selected individuals whose longevity we are investigating. Proceeding on this basis, I tried to determine the age at which, on the average, men of genius had accomplished a work sufficient to entitle them to be so denominated. This investigation was instigated by Mr. C. S. Peirce, then in charge of courses in logic at the Johns Hopkins University. Under his leadership a small company, of whom I was one, proposed to study certain traits of great men, and for this purpose we tried to select the three hundred greatest men of all times. The work was never carried on to completion, so that the final selection of the names, and particularly their use in the present connection, must rest on my sole responsibility. I mention these facts mainly to indicate the general representative character of the list which I used. I take from my previously published article the following essential facts: Omitting all doubtful names, about two hundred and fifty names remain, presenting a list which most persons would agree to be fairly representative of the greatest men of all times. Of these again I selected at random those about whom it was easiest to fix the age at which they had done work which would entitle them to a place on this list, or work which almost inevitably led to such distinction. It is a date about midway between the first important work and the greatest work. The average of over sixty such ages is thirty-seven years; which means that, on the average, a man must be thirty-seven years old in order to be a candidate for a place on this list. The real question, then, is, How does the longevity of this select class of thirty-seven-year-old men compare with that of more ordinary individuals? The answer is given by the expectation of life at thirty-seven years, which is twenty-nine years, making the average age at death sixty-six years. And this is precisely the age at death of these sixty great men; showing that, as a class (for these sixty may be considered a fair sample) great men are not distinguished by longevity from other men.
It will thus be seen that my own conclusion is entirely opposed to that of Mr. Thayer. But this opposition rests not upon a difference of data, but upon a difference of logic. To my mind the enumeration of ages at death of any number of great men cannot prove unusual longevity unless we take into consideration and can determine the number of years which, on the average, a person must have lived in order to become a candidate for the class under consideration. The comparison with the average age (that is, the period of about thirty-five or more years) is not only false; it is essentially absurd; for it would become possible only if we had among poets, and painters, and musicians, and historians, and scientists, and generals a goodly number who succumbed to the diseases of early infancy, or to some of the ills that juvenile flesh is heir to.
It may be well to illustrate at this point just what conclusions may be drawn from the data which Mr. Thayer and other writers have presented. The first conclusion is that it takes a considerable length of time to become eminent—on the whole a very natural and comprehensible statement. And with regard to the astronomers previously mentioned it is even possible to go farther; for these astronomers have been divided into four degrees of eminence, and it is found that astronomers of the first rank are longer-lived than those of the second, and these in turn are longer-lived than those of the third class, and these in turn are longer-lived than those of the fourth class. Therefore, the author concludes, the greatest astronomers have been most favored with length of years, and adds, as practical advice, “Be an astronomer and live long.” Now, of course, the true conclusion is that it takes longer to accomplish work which will entitle one to pre-eminence amongst astronomers than to do work which will only achieve moderate distinction. And the practical conclusion would read, “Live long enough to become great as an astronomer and you will probably, with the ordinary expectation of life, have a good chance of completing your three score and ten.” In the same way Mr. Thayer’s list of nineteenth-century celebrities might fairly be said to suggest the conclusion that in the present century one must already have labored for a goodly number of years before one’s name would be selected by a student of the longevity of great men. So far, then, these facts have an interesting interpretation.
It may also be worth while to note that if all the men whose longevity is to be compared are of a comparable class (that is, comparable with regard to the attainment of years which they assume), then the longevity of different groups of celebrities may be compared with one another. Thus it is possible to compare the longevity of musicians with that of scientists (of about equal eminence), and according to Mr. Thayer’s lists the scientists lived ten years longer than the musicians. The same conclusion appears in my own study, in which the scientists appear amongst the longest-lived, and the musicians amongst the shortest-lived men of genius. This conclusion must not be pressed too far, but in a general way it certainly is a bit of evidence worthy of consideration as proving that distinguished scientists live longer than distinguished musicians. It would be wrong to draw rigid conclusions from comparisons of small groups, and therefore it is better to contrast the average age at death of the various men studied in as large and as general classes as possible; e. g., as men of thought, men of feeling and men of action. All of the studies with which I am acquainted point to the conclusion that men of thought live longer than those who achieve distinction through unusual qualities of their emotional natures.