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February 11, 1939

The Social Life of Animals

JAMA. 1939;112(6):575. doi:10.1001/jama.1939.02800060091035

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Out of a wealth of personal experimentation and an exhaustive study of the work of other, experimenters, an effort is made to show the relation between population and development of vital processes. The author holds that (p. 51) the struggle for existence in certain brackets is mainly a matter of populations, measured only in the long run, and then by slight shifts in the ratio of births to deaths. Experiments with various forms of animal life, from protozoa to mammals, indicate that a certain minimum population is essential to the most rapid development of some of the vital processes and that this development declines with a certain maximum population. He believes that this characteristic originates so low in the stage of evolution that its influence produces a law that extends up through the two main phyla of the animal world. In explanation it is suggested that association of a certain

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