This theory is supported by arguments that base on environmental determinism. In essence, the theory focusses on the fact that the adoption of bipedalism by the hominids was caused by the drying up of vegetation because of adverse environmental conditions such as global warming and other forces within the atmosphere. Parts of this theory could be understood within the framework of Darwinian concept of survival for the fittest. In order to survive the harsh conditions engendered by the drying up of vegetation, it became necessary for the hominids to change from its old forms of posture to bipedalism in order to enhance mobility and maximize the utility of a new environment without forests (Strickberger 474). Scrutiny of the savanna-based theories reveals certain inconsistencies, which appear to affirm the position that the early kinds of the hominids were essentially diverse in the manner in which they mingled with the environment. There is no sufficient proof that shows the actual point of transformation between in the posture of the hominids. The fact of matter shows that some of the hominids actually showed signs of having acquired the erect posture and the bipedal movements even before their movements into the savannah kinds of existence. Another important point that has been used to lay stress on the deficiencies of the argument could be seen in the fact of the lack of evidence of hominids that lived in the forests. The common argument shows that the various aspects that attempt to
connect the transition of posture among the hominids must explain the manner in which hominids lost their past posture and the causal relations between the changes in the environment and the acquired conditions of posture as explained in the context of these changes. Any mismatch between the causal factors and the eventual outcome implies some significant weaknesses in the logic of the theory. It would imply that alternative forces other than the changes in the environment caused the adoption of bipedal postures for the hominids. The postural feeding hypothesis is the second hypothesis that has attempted to explain the origin of bipedal hominids. According to this hypothesis, some hominids such as chimpanzees were only bipedal during moments of eating. Kevin Hunt remains one of the well-known proponents of this hypothesis. This hypothesis provides that many of the animals that conformed to the bipedal postures attained their status out of habit (Lewin 112). The bipedal posture was therefore a product of posture and could only be achieved and retained through consistent practice. This theory is consistent with other biological theories that affirm that animals often gain or lose certain features or characters through consistent practice. The hypothesis also weaves into the common biological argument that attempts to connect changes in genetics to environmental factors. As such, it might be argued that the merits of this argument should be examined in light with all the attendant factors that connect character with formal change. The matter of convenience features prominently in the many arguments that relate to the hypothesis of postural feeding. Convenience in eating is one of the major factors that studies in fossil anatomy use in the process of determining the level of change as reflected within the element of change and balance.