The evolution of the upright posture and gait—a review and a new synthesis

During the last century, approximately 30 hypotheses have been constructed to explain the evolution of the human upright posture and locomotion. The most important and recent ones are discussed here. Meanwhile, it has been established that all main hypotheses published until the last decade of the past century are outdated, at least with respect to some of their main ideas: Firstly, they were focused on only one cause for the evolution of bipedality, whereas the evolutionary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. Secondly, they were all placed into a savannah scenario. 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. (Nature 412:175–178, 2001)). Moreover, the fossil remains revealed increasing evidence that this part of human evolution took place in a more humid environment than previously assumed. The Amphibian Generalist Theory, presented first in the year 2000, suggests that bipedalism began in a wooded habitat. 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. 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. So far, this is the only scenario suitable to overcome the considerable anatomical and functional threshold from quadrupedalism to bipedalism. This is consistent with paleoanthropological findings and with functional anatomy as well as with energetic calculations, and not least, with evolutionary psychology. The new synthesis presented here is able to harmonise many of the hitherto competing theories

Alfred Russel Wallace: Self-educated genius and polymath

Alfred Russel Wallace was a Colossus: courageous, heroic, radical, modest, and above all, a man of insatiable curiosity. One hundred years on one can propose that his prescience anticipated many modern scientific developments and that despite relative neglect his far-ranging insight continues to inspire even now. His earliest memories take us to Usk in South Wales, where he was born in 1823, and many experiences there are fondly recounted as formative influences. Adolescent interest in natural history during apprenticeship to his elder brother, a land-surveyor at the dawn of the railway era in Mid Wales and the Neath valley, blossomed into a lifelong fascination with the living world. The depth and reach of his thinking on the diversity and distribution of species outpaced his contemporaries, and he became the undisputed father of biogeography. Interaction with the ‘poor farmers’ of South Wales and exposure to their humble conditions inculcated a concern for the deprivation of the underclasses, and were influential in the shaping of his societal concerns and later activism. After proposing the basic principles of speciation and of selection and arriving at a novel and original concept of evolutionary mechanisms, Wallace daringly pursued several non-scientific interests: phrenology, mesmerism, spiritualism, and the great question of whether we are alone in the cosmos. Honoured late in a long life, Wallace became regarded as one of the greatest scientists in the world, despite his enthusiasms for supernatural phenomena. Eclipsed after his passing in 1913, a gradual realisation of the depth of his mainstream science as well as premature dismissal of some of his more arcane insights continues beyond his centenary year