ABSTRACT
A model of hominid origin proposed by Jolly uses analogy to anatomical and behavioral characters shared by Theropithecus gelada and some early hominids. He suggests that early hominid populations relied on small-object feeding, that this dietary specialization led to a suite of adaptations to the grassland savannah, and that bipedality developed in response to feeding posture. There is an obvious trend toward prolonged life-span, which has both physiological and demographic correlates bearing directly on the phyletic origin of hominids. Primates, which are the most intelligent mammals, have achieved evolutionary success primarily by their social and reproductive behavior, which is their most developed original character. The proposed model accounts for the early origin of bipedality as a locomotor behavior directly enhancing reproductive fitness, not as a behavior resulting from occasional upright feeding posture. If the model is correct, the conventional concept that material culture is pivotal to the differentiation and origin of the primary characters of the Hominidae is probably incorrect.
