Excerpted from The Science Times Book of Fossils and Evolution, edited by Nicholas Wade, this article outlines the major hypotheses, past and present, that attempt to explain the evolution of bipedal walking in human beings. From environmental to social/behavioral change, many factors may have influenced our early ancestors. John Noble Wilford outlines scientists' various arguments and counter arguments.
Discuss the relationship between fossil evidence and molecular evidence in assigning time periods to the various divisions in primate evolution, especially the ape-hominid split and the later split between the common ancestors of chimpanzees and humans.
Discuss the ways in which studies of ancient climate and geology contribute to the study of hominid evolution.
Discuss several current hypotheses about the driving forces behind the evolution of bipedality, giving the strong and weak points of each hypothesis. What kinds of data do proponents of the various hypotheses have -- or need -- to confirm or reject competing ideas?