Historical Remarks Bearing on the Discovery of Pan paniscus Whether by accident or by design, it was most fortunate that Robert M. Yerkes, the dean of American primatologists, should have been the first scientist to describe the characteristics of a pygmy chimpanzee, which he acquired in August 1923, when he purchased him and a young female companion from a dealer in New York. The chimpanzees came from somewhere in the eastern region of the Belgian Congo and Yerkes esti mated the male's age at about 4 years. He called this young male Prince Chim (and named his female, com mon chimpanzee counterpart Panzee) (Fig. I). In his popular book, Almost Human, Yerkes (1925) states that in all his experiences as a student of animal behavior, "I have never met an animal the equal of this young chimp . . . in approach to physical perfection, alertness, adaptability, and agreeableness of disposition" (Yerkes, 1925, p. 244). Moreover, It would not be easy to find two infants more markedly different in bodily traits, temperament, intelligence, vocalization and their varied expressions in action, than Chim and Panzee. Here are just a few points of contrast. His eyes were black and in his dark face lacked contrast and seemed beady, cold, expressionless. Hers were brown, soft, and full of emotional value, chiefly because of their color and the contrast with her light complexion.