Historians of science have only just begun to sample the wealth of different approaches to the study of animal behavior undertaken in the twentieth century. To date, more attention has been given to Lorenzian ethology and American behaviorism than to other work and traditions, but different approaches are equally worthy of the historian's attention, reflecting not only the broader range of questions that could be asked about animal behavior and the "animal mind" but also the different contexts in which these (...) questions were important. One such approach is that represented by the work of the French zoologist Louis Boutan (1859-1934). This paper explores the intellectual and cultural history of Boutan's work on animal language and the animal mind, and contextualizes the place of animal behavior studies within late-nineteenth- and early-twentieth-century French biology. I explore the ways in which Boutan addressed the philosophical issue of whether language was necessary for abstract thought and show how he shifted from the idea that animals were endowed with a purely affective language to the notion that of they were capable of "rudimentary" reasoning. I argue that the scientific and broader socio-cultural contexts in which Boutan operated played a role in this transition. Then I show how Boutan's linguistic and psychological experiments with a gibbon and children provide insights into his conception of "naturalness." Although Boutan reared his gibbon at home and studied it in the controlled environment of his laboratory, he continued to identify its behavior as "natural." I specifically demonstrate the importance of the milieu of the French Third Republic in shaping Boutan's understanding not only of animal intelligence and child education, but also his definition of nature. Finally, I argue that Boutan's studies on the primate mind provide us with a lens through which we can examine the co-invention of animal and child psychology in early-twentieth-century France. (shrink)