The possibility to walk on two legs was the most popular trait in the hominid lineage. Bipedalism established the distinction between the first hominids and the other apes although big brains were previously thought to be the unique feature.
There are several factors which prompted humans to become bipeds based on the theory of evolution. First, humans employed certain postures when gathering food which necessitated them to hang their arms and climb vertically on trees (Preuschoft 366). The feeding habits not only had an impact on the human anatomy, but they also caused the organism to change his stance to one which was upright. During the fruit gathering process, early man had to develop torso formation which led to arm hanging. As this was done regularly, the bipedalism eventually turned into a habit.
Second, the behavioral model contended that the social behavior of humans made them bipedal. The sexual behavior of early man depicted a monogamous structure of interactions between the males and females although the former turned out the stronger one (Stanyon and Bigoni 582). The man was forced to make use of the upper limbs to carry food for their companions making him appear protective. Therefore, males had to use their two limbs in the search for mates.
Third, the early man felt the effect of high temperatures, and to limit the impact; he tried to reduce the surface exposed to direct heat. Accordingly, walking on two limbs was the most effective strategy to reduce the surface exposed to the sun. Moreover, this posture raised the body surface higher to reach the cooler temperatures and winds. Similarly, it reduced the rate of evaporative cooling temperature enabling the body to retain more water.
In summary, bipedalism was the most vital factor which distinguished early man from other four-legged apes. The most influential factor for the adoption of upward walking was postural feeding.
Works Cited
Preuschoft, Holger. "Mechanisms for the acquisition of habitual bipedality: are there biomechanical reasons for the acquisition of upright bipedal posture?" Journal of Anatomy 204.5 (2004): 363-384.
Stanyon, Roscoe and Francesca Bigoni. "Sexual selection and the evolution of behavior, morphology, neuroanatomy and genes in humans and other primates." Neuroscience & Biobehavioral Reviews 46 (2014): 579-590.
