A new morphometric analysis of the hominid pelvic bone

This study is based upon a new morphometric technique providing both size a nd shape variables. It has been applied to 189 pelvic bones of extant human s and African apes as well as to 13 hominid pelvic bones of various taxonom ic status. The main aim of this work is to include such fossil bones in the same study in order to set a synthetic comparison of their shape in the li ght of the yardstick given by the African ape/human pelvic bone comparison. To do so, ratio diagrams are chosen because they are simple and very expre ssive tools with which to present such comparisons. Shape differences are v ery well illustrated and quantified by this technique. The ilium appears to be the most different of the three parts of the pelvic bone. Compared to t hese differences, discrepancies between fossil hominid and extant human bon es are of a totally different scale. This shows the architectural unity rel ated to the acquisition of bipedalism by hominids. It is nonetheless possib le to detect two levels of difference. The first separates Australopithecus from Homo and could be seen as reflecting locomotor differences between bo th genera. The second splits both Homo erectus and Neanderthal from modem h uman pelvic bones. It appears from the hominid fossil record of pelvic bone s that two periods of stasis exist and are separated by a period of very ra pid evolution corresponding to the emergence of the genus Homo. We are of t he opinion that the same could be true for the split between African ape an d hominid lineages at the end of the Miocene. (C) 2000 Academic Press.