Bipedalism

Through the use of experimental studies, it can be concluded that locomotion in human beings showed that the evolution of bipedalism was more an intricate transformation rather than a simple transition from quadrapedalism. These studies also suggested that bipedalism first came about from an arboreal ancestor, rather than a terrestrial, land ancestor.

1. A 2007 study suggests that energy was the primary reason why bipedalism (walking on two legs) arose from quadrapedalism (walking on four legs or ‘knuckle walking’). Because of the reduction in energy expended from walking on two legs, it is suggested that this provided evolutionary advantages, and allowed chimpanzees to better accommodate to the varying terrestrial phenomena. It’s concluded that the smaller the chimpanzees steps, the greater the energy it uses. From the data gathered in the report it can be assumed that energy consumption in chimpanzees played a significant role in the transition from quadrapedalism to bipedalism. The findings allow researchers to examine adaptations such as the lengthening of limbs that may have contributed to the evolution of bipedalism in chimpanzees.

2. A second study from the University of Illinois which involved the study of biomechanics, that is, locomotion, joint movement and stress in bones and limbs assumes a dissimilar perspective to the notion put forward above. The hypothesis that is reached by a team of paleoanthropologists is that the evolution of upright walking is a result of a number of environmental factors. The abundance and wide varieties of food sources and varying terrain are just a few aspects which may have caused walking on all fours to evolve. Another reason suggested is the use of tools and weapons amongst chimpanzees which would have required the use of their hands. This may give us a better understanding to why humans walked upright and the terrestrial features in our anatomical make up which may support the theory that many early hominid species, despite the fact they were bipedal, were arboreal climbers.

3. The basis of this journal article implies that food gathering was the central reason in the evolution of bipedalism. This then suggests that hominid bipedalism may have evolved from the use of arm hanging from chimpanzees which allowed them to harvest fruit and other foods from trees. Anatomical evidence gathered from Australopithecus afarensis agrees with the above article stating characteristics in the shoulders and arms indicate a life of arm hanging. The hip and pelvis bones also portray symbols of bipedal walking. The journal can best be summed up as putting forward the idea that the evolution of bipedalism was the result of the need for an improved feeding or hunting adaptation rather than for terrestrial advantages. Hence, the central theme disagrees with that of the main article which comes to the conclusion that the walking on two legs arose from greater energy efficiency.

References

Journal Articles

1. Schmitt, D. 2003 ‘Insights into the evolution of human bipedalism from experimental studies of humans and other primates’ Journal of Experimental Biology Vol. 6 No.2 pp. 1437-1448

2. University of Arizona (2007, July 17). Study Identifies Energy Efficiency As Reason For Evolution Of Walking Upright Walking. Science Daily Retrieved 2 September, 2011, from http://www.sciencedaily.com/releases/2007/07/070716191140.htm

University of Illinois at Urbana-Champaign (2002, May 9). Origin of Bipedalism Seems Most Likely Tied To Environmental Changed Science Daily Retrieved 2 September, 2011, from http://www.sciencedaily.com/releases/2002/05/020509074029.htm

3. Hunt, D. K. 2002 ‘The Evolution of Human Bipedality: ecology and functional morphology’ Journal of Human Evolution Vol 26 No.3 pp.183-202