What do the chimpanzees tell us about early hominids?
The behavior of wild chimpanzees suggests that several aspects of the positional behavior of earliest hominids may have been given less attention that they merit. First, arboreal bipedal posture is not dichotomous with arboreal quadrupedal posture. Bwindi chimpanzees moved fluidly between four-legged, three-legged, and two-legged postures while feeding in tree crowns. Their use of three-dimensional space in tree tops incorporated elements of positional behavior most often seen as binary states. This fluid quadrupedal-bipedal shifting may have occurred in the earliest hominids as well. Arguments about whether early hominids were fully adapted to bipedal walking, or facultatively arboreal, have been carried on for at least three decades (Susman et al., 1984; Lovejoy, 1988). Recent evidence suggests that knuckle-walking may have been employed by the immediate ancestors of the australopithecines (Richmond and Strait, 2000). Chimpanzee bipedal behavior suggests that early hominids likely en
