a rat and a bat have similar metabolic rate, but a bat lives several times longer. More recently, further doubts have been raised on the Rate of Living Hypothesis by the demonstration that, when modern statistical methods for correcting for the effects of body size and phylogeny are employed, metabolic rate does not correlate with longevity in mammals or birds. (For a critique of the Rate of Living Hypothesis see Living fast, dying when?.) Social habits and death Pearl was widely known for his lust for life and his love of food, drink, music and parties. He was a key member of the Saturday Night Club which also included H. L. Mencken. Prohibition made no dent in Pearl's drinking habits (which were legendary). Raymond Pearl is, also, known for his population biology work, as in his 1928 volume, The Rate of Living: Being an Account of Some Experimental Studies on the Biology of Life Duration. In this book, he presents extensive research regarding population density effects on life duration in fruit flies, demonstrating that an optimal population density existed for that insect in his experimental model. This raised the question of whether or not the same effect might not occur in other species, including humans. His work demonstrating longer lifespans for flies with lower metabolic rates, also, raised the question of whether or not a similar phenomenon might be found in other species, including humans. Thus, he became a mentor to John B. Calhoun, famous for his ecological studies of rodent populations and their possible importance for modern humans. Population density effects on duration of life is thought, by population biologists, to be Raymond Pearl's greatest contribution to biological science. In November 1940, Pearl was in apparently good health and paid a visit to the Baltimore Zoo. He cut his trip short complaining of chest pains and died later that day. See also Life extension Maximum life span Senescence (aging theories) References Further reading External links American Philosophical Society Raymond Pearl Papers The Papers of Raymond Pearl at Dartmouth College Library 1879 births 1940 deaths People from Farmington, New Hampshire University of Michigan alumni Biogerontologists American biologists Researchers in alcohol abuse Presidents of the American Statistical Association Fellows of the American Statistical Association American statisticians Writers from New Hampshire Mathematicians from New Hampshire Proceedings of the National Academy of Sciences of the United States of America editors