FEATURES OF HUMAN BIPEDALISM: A NEW LOOK AT AN OLD PROBLEM

Homo sapiens sapiens' highly specialized means of locomotion, evidently unique to our phylogenetic line, requires a corresponding number of mutations for its first complete articulation. The available time spans depend on the duration and extent of directed selection pressure. Both factors are responsible for the modification of those structures that optimized the adaptation of pressure-impulse transmission and can be secured under the operating of special conditions. Concerning both aspects – optimization and mutation of underlying genetic steering mechanisms – principally such morphological structures were studied as depending directly on modern human bipedalism. The characteristics of the upper extremity could therefore be omitted. The manner in which the Homo sapiens sapiens centre of gravity of body weight has been displaced is relevant, under prevalent biomechanical and hydrodynamic regimes. Cross-comparison with other representatives of the Hominoidea closely related to modern Homo sapiens sapiens makes abundantly clear where the key modifications to the Extremitas inferior are evident. The results of examinations of femur and tibia conducted enable relatively clear-cut, indeed unambiguous criteria, to be stated with respect to assessing the bipedal adaptation of Homo sapiens sapiens. Concerning only the two characteristics of the distal femur, assessments of the degree of adaptive proximity to truly modern human bipedalism exhibited by fossil finds of representatives of Hominoidea are, to a large extent, highly reliable. The results in question need only be compared with previously published results (i.e. McHenry, Corruccini 1978, Day 1984, Aiello, Dean 1990 or the overview of Brandt 1995 with 429 references). In this way it is easy to obtain a relatively clear cut between human bipedalism and non-human bipedalism on corresponding fossil finds of early representatives of Hominoidea.