A Group of Young Chimpanzees in a One-Acre Field1 1The collection of data for this chapter was supported by grant FR-00164 from the National Institutes of Health to the Delta Regional Primate Research Center of Tulane University, the writing of this chapter by National Science Foundation grant GU-3850 to the Psychobiology Program of the State University of New York at Stony Brook. Without the encouragement and advice of William A. Mason, Arthur J. Riopelle, Helmut Hofer, and Hans Kummer some of the experiments might not have been initiated, and without the assistance of Palmer Midgett, Jr., few of the experiments could have been conducted.