Obligate Bipedal Locomotion in the Modern Human: A Review of Musculoskeletal Modifications

Several attributes are only found in primates, some of these are even more unique and noticeable in humans. These may not be limited to; energy-saving bipedal posture and locomotion, stable supine posture, complex manual skills and tool making abilities, hierarchical social structure and cultural organisation, augmented cranial capacity, a more developed frontal lobe, and language proficiency. From a Darwinian point of view, an erect posture and locomotion have evolved to free the hands for the purpose of tool-making. However, more recent theories suggested that bipedal locomotion was related to environmental factors which led to the advent of distinctive and remarkable anatomical features for a form of locomotion that is more energy-economic than quadrupedal locomotion in non-human primates and other members of the animal kingdom. These anatomic features and adaptations include; adjustments to the general body architectural plan, in addition to cranial and postcranial modifications. Postcranial modifications are debated to be the most critical for a stable and fuel-efficient upright walking, other anatomic adaptation were complimentary. The most significant of these anatomical changes took place post-cranially particularly at the level of the pelvis. These changes can be traced back to Australopithecus afarensis dating to at least 3.6 million years ago. The overall level-of-evidence of this article is estimated to be of level-2b, which is well-positioned within the pyramidal hierarchy of level-of-evidence.