What is a question about this article? If the question is unanswerable, say "unanswerable".

Between 1925 and 1940, philanthropic foundations, especially ones connected with the Rockefellers, contributed about $7 million to support the Yale Institute of Human Relations and the affiliated Yerkes Laboratories of Primate Biology. The money went toward behavioral science research, which was supported by foundation officers who aimed to "improve mankind" under an informal, loosely defined human engineering effort. The behavioral scientists at Yale, led by President James R. Angell and psychobiologist Robert M. Yerkes, tapped into foundation largesse by crafting research programs aimed to investigate, then suggest, ways to control, sexual and social behavior. For example, Yerkes analyzed chimpanzee sexual behavior in hopes of illuminating the evolutionary underpinnings of human development and providing information that could ameliorate dysfunction. Ultimately, the behavioral-science results disappointed foundation officers, who shifted their human-engineering funds toward biological sciences.

What animals eating behavior did Yerkes study?
unanswerable