Yerkes, Robert Mearns (1876-1956) was an American psychologist known for his research on the behavior of apes. His most important book is The Great Apes: A Study of Anthropoid Life (1929), which his wife, botanist Ada Watterson Yerkes, helped him write. He also wrote The Mental Life of Monkeys and Apes (1916) and the three-volume The Mind of a Gorilla (1927โ€“1928).

Yerkes was born in 1876 in Breadysville, Pennsylvania. He earned a Ph.D. degree from Harvard University in Cambridge, Massachusetts, in 1902 and taught psychology there until 1917. While there, he served as consultant to the Boston Psychopathic Hospital, where he became interested in mental testing. During World War I (1914โ€“1918), he introduced the first large-scale use of psychological tests in the armed services.

Meanwhile, Yerkes focused on primate learning and behavior He saw a need to establish an institute for the systematic study of primates. During 1923 and 1924, Yerkes raised two chimpanzees in his home. He wrote Almost Human (1925) and co-wrote Chimpanzee Intelligence and Its Vocal Expressions (1925) based on this experience.

As early as 1916, Yerkes had written about the need for the establishment of primate research. In 1924, he joined the Institute of Psychology at Yale University to do further primate research. He also served as professor of comparative psy-chobiology. In 1929, Yerkes founded and became director of the Yale Laboratories of Primate Biology in Orange Park, Florida, which housed the first U.S. experimental primate breeding colony.

Yerkes died in 1956. In 1965, with funding from the National Institutes of Health, the center moved to Atlanta, Georgia. It is now the Yerkes Primate Research Center, one of the leading centers for biomedical and behavioral research with nonhuman primates.