Chimpanzee referential models for early hominid behavior have become the most common of all current approaches. In addition to chimpanzees' close evolutionary relationship to humans, the justification for this approach is that their behaviors are complex and human-like compared with those of other animals. An examination of four aspects of chimpanzee society that are prominent in discussions of human evolution-bipedal posture, tool use, cooperative hunting, and culture-indicates that other animals, even nonprimates, engage in analogous behaviors. Some referential models describe early hominid niches (e.g., locomotion, meat procurement) as presumably similar to those of extant great apes, but observed fossil anatomy suggests otherwise. Others attempt to explain hominid innovations with chimpanzee-like behaviors (e.g., bipedal posture, simple tool use, social hunting) when basic evolutionary theory dictates that only differences between closely related forms explain their divergence. Although data on the great apes are crucial for origins modeling, they are too often misapplied in reference to human behavioral evolution. Reprinted by permission of the University of Chicago Press. © All rights reserved