Characteristics Of Human Bipedalism

One characteristic that many people believe it distinguishes Homo sapiens from other apes like chimpanzees or bonobos is our capacity for intelligence. Another distinguishing trait is the human capacity for a full time bipedalism. So It is no accident that many anthropologists have recognized a correlation between human bipedalism and intelligence. Carl Ernst von bear once remarked “Upright posture is only the consequence of higher development of the brain”. It is hypothesized that bipedalism allowed hominins to use their hands for stone tools and more efficient forging, considering that the brain is the most metabolically taxing organ in the body, in humans at least, it takes about twenty percent of our energy consumption. It is hypothesized

So it is important to address the question of whether correlation entails causation. First, let’s explore some of the morphological characteristics that allow for bipedal locomotion and then we will examine a few of the leading hypothesis into why and how bipedalism was favourably selected in the hominin lineage. So there are several morphological characteristics which differentiate human and chimp bipedalism, firstly, chimps are unable to fully extend their knee joints, making it physically impossible for them to stand straight. Chimps also lack the valgus angle which is critical for efficient bipedal locomotion. The human femur is angled inward from the side of the knee, maintaining the body’s centre of gravity over the knees and feet , allowing for more efficient balance and energy conservation. This is why chimps waddle back and forth when they walk because they must shift the centre of gravity to each leg. Examining the fossil of Australopithecus afarensis and extinct hominid ancestor, we can conclude that it was at least partially bipedal due to the presence of the valgus angle among other morphological characteristics. The human spine is curved slightly and is s-shaped, enabling human to walk upright with less muscular effort, also the way an upright body is then rested upon the feet, which in the case of humans, have lost their grasping specialization in favour of balance and proportion for more efficient locomotion by the

Most notably, the pelvis gets shorter from top to bottom and the iliac blades become more flaring and lateral. By one model, the arboreal model, the Australopithecus were surely bipedal when they were on the ground, but the argument is that they did not spend all of their time on the ground. They were still climbing trees probably to get away from carnivores, or they were sleeping up on the trees, were going after food resources. And because they were spending some of their time on the ground and on the trees, they had to have a locomotive skeleton which in competent to both of those things. Therefore, there had to be compromises that were made. According to this model, Lucy and other Australopithecus, basically, selection was constrained to the extent to which it could improve their skeleton for bipedalism because they had to be competent climbers. And because of this, it had been suggested that when they did walk terrestrially, they walk in a different way that they probably walked more like a chimpanzee walks bipedally, with partially flexed hip and a flexed knee. So the argument goes that with the origin of the genus homo, like this early Homo erectus skeleton from Africa that the genus homo was fully terrestrial and now this constraint is lifted and now