RAYMOND PEARL '99 AN EDITORIAL
[The following editorial comment appeared in the New York Times.]
IN THE EARLY years of the century London was the only place where population problems could be studied. And about the only man who was competent to treat those problems scientifically and statistically was Karl Pearson, founder of what he called "bionmetry." Following Kelvin's principle that science is measurement, Pearson measured when he could and drew shrewd deductions. To him came a young man from the United States. He was Raymond Pearl. Now that he has died at the much too early age of 61 it becomes the duty of his colleagues to take stock of his many and varied accomplishments. They will agree that he was one of their leaders, the man who gave the scientific study of population a healthy impetus which has resulted in a fine American school of demography and which has indicated the probable course of populations under the stress of modern social conditions.
What distinguished Professor Pearl's work was his substitution of experimenting and statistical analysis by powerful mathematical methods for hypothesis and speculation. He measured human beings as Pearson did. He analyzed statistically mortality and birth rates, two fundamentals in population growth and decline. No finer studies of the relation of food supply to population were ever made than hisstudies that had a very practical application during the last war. Particularly important were his researches in human fertility, set forth in his "Natural History of Population." Though he was by no means the first to use lower forms of animal life to study density of population—the great Pasteur had made some classic experiments with yeast cells—his studies of fruit flies kept in half-pint milk bottles had a profound effect on the experts. No infallible law emerged. Professor Pearl himself readily ily admitted that fruit flies are not human beings, that his milk-bottle universe is not ours, however limited both may be, and that the logistic curve of Verhulst, which he verified and which showed how the growth of his fruit-fly populations was governed by their own density, might not fit humanity. Yet the fact remains that the curve does fit remarkably well the case of the United States from about 1800 to 1930.
If Professor Pearl was by far the best known of population experts it w7as because of remarkable literary gifts and a trenchant and even dramatic way of presenting his results that appealed to the popular imagination. That same gift was invoked to present researches undertaken as an offshoot of his population studies. Thus he illuminated tuberculosis, the effect of alcohol and tobacco on longevity, public health and epidemiology, biology and war. Under his editorship "Human Biology" and the "Quarterly Review of Biology" became authoritative organs. He it was who was the leading spirit in the formation of the International Union for the Scientific Investigation of Population Problems, the embryo out of which the Population Association of America developed. As a result he left human biology a richer science than it had been, with demographers working as an organization. The rapidly growing literature on population testifies abundantly to his enduring influence.
