Abstract
In the study of human evolution, remarkable advances were made in the latter half of 20th century, e.g. clarification of the phylogenetic status of hominine lineage based on molecular biological evidences, and morphological assessments of Miocene hominoids and Pliocene hominines through palaeontological materials. With respect to the evolution of bipedality, a variety of studies were carried out making use of telling materials including Australopithecus afarensis partial skeleton and Laetoli footprints. The reason for and the circumstances under which hominine bipedality emerged were variously formulated in major theories, in line with the Y. Coppens’ scenario of adaptive shift in early hominines from woodlands to open environments. However, the discovery and recently disclosed morphology of Ardipithecus ramidus, assumed to have been a woodlands dweller but characterized with extremities and ilia suggesting arboreality and bipedality, respectively, have changed these situations dramatically. Unfortunately, the reason why bipedality emerged in the woodlands solely in the hominine line has not been identified yet.
