2000) In the Late Miocene, the long-armed Oreopithecus bamboli may have developed a kind of terrestrial bipedalism in the absence of predators that was very different from the human one (Köhler and Moyà-Solà 1997a Rook et al. During Miocene evolution, there appeared several fossil primates showing, to various degrees, adaptations for an orthograde posture (Nakatsukasa et al. Moreover, neither dinosaurs nor ostriches or any other sauropsid or marsupial moving on their hind feet show an orthograde spine in locomotion (Niemitz 2004). Even among all land-dwelling vertebrates, human bipedalism is unparalleled, since erect-walking penguins, with their short rudder-like feet, have a completely different functional anatomy and biomechanics (cf. The habitual orthograde human posture and locomotion using harmonic cycles of anatomical pendulums are unique among all mammals (e.g., Gebo 1996 Schmitt 2003 Vaughan 2003). The new synthesis presented here is able to harmonise many of the hitherto competing theories. This is consistent with paleoanthropological findings and with functional anatomy as well as with energetic calculations, and not least, with evolutionary psychology. So far, this is the only scenario suitable to overcome the considerable anatomical and functional threshold from quadrupedalism to bipedalism. In contrast to all other theories, wading behaviour not only triggers an upright posture, but also forces the individual to maintain this position and to walk bipedally. The forests were not far from a shore, where our early ancestor, along with its arboreal habits, walked and waded in shallow water finding rich food with little investment. The Amphibian Generalist Theory, presented first in the year 2000, suggests that bipedalism began in a wooded habitat. Moreover, the fossil remains revealed increasing evidence that this part of human evolution took place in a more humid environment than previously assumed. During the 1990s, the fossil record allowed the reconstruction of emerging bipedalism more precisely in a forested habitat (e.g., as reported by Clarke and Tobias (Science 269:521–524, 1995) and WoldeGabriel et al. Secondly, they were all placed into a savannah scenario. Meanwhile, it has been established that all main hypotheses published until the last decade of the past century are outdated, at least with respect to some of their main ideas: Firstly, they were focused on only one cause for the evolution of bipedality, whereas the evolutionary process was much more complex. The most important and recent ones are discussed here. During the last century, approximately 30 hypotheses have been constructed to explain the evolution of the human upright posture and locomotion.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |