ANTHROPOLOGY – BIPEDALISM 7
An apparent trait depicted by humans, not shared by numerousdifferent animal species on earth, is the capability to walk usingtwo feet. The trait refers to bipedalism, and it plays a majorfunction in the pathway of human evolution. Bipedalism is a type ofterrestrial locomotion whereby creatures move via use of rear limbs.It is exclusively associated with humans because even though otheranimals are capable of walking on two limbs, they do so occasionally.There are many different hypotheses, which explain why and the mannerof bipedalism evolution in humans. It evolved prior to the humanbrain or advancement of stone tools. Bipedal research is traced inAustralopithecus remains dating 4.2 to 3.9 million years back(Strickberger, 2000). Probable causes resulting in human bipedalismevolution involve freeing hands to carry and utilize tools,alterations in weather and environment favoring a raisedeye-position, sexual dimorphism during food collection and efforts inreducing skin exposure to the sun.
Past Evolution of Human Bipedalism
Scientists suppose that pre-bipedal primates were earthlyquadrupeds, possibly knuckle-walkers similar to current gorillas,chimpanzees and bonobos (Lewin, 2005). Anthropological research notesthat it is also probable that the initial habitual walkers were wellversed for terrestrial bipedality, with adaptations facilitatingbipedal running amid branches and boughs, upward standing to searchoverhead, and vertical tree climbing (Lewin, 2005). The scenarioderives from research on gibbons, which often employ arborealactions. Gibbons have long and strong lower limbs, similar figure oflumbar vertebrae as humans, and humanoid chest configuration. Gibbonsstand straighter compared to chimpanzees when walking (Lewin, 2005).By studying the features of gibbons and other primates, it has beenpossible to explain the evolution of bipedalism. The features includeadoption of a bipedal posture with complete extension of the hindlimbs. The foot may possibly have gone via the most dramaticalteration, from a prehensile to heel-supported organ. Enhanced sizeand often-continuous erect posture on extended hind limbs favored theevolution of humanoid knee, foot and hip arrangement (Ogihara &Yamazaki, 2001).
Early primates believed to have evolved to human beings, Homoergaster and rudolfensis are characterized by long femursof contemporary human arrangement and interior knee structure as thatof Homo sapiens (Strickberger, 2000). The structures differfrom those of chimpanzees and several small tree-climbing primates.Such features define the period when the distinguishing morphology ofhuman calf muscles evolved. Dissimilar to those of enormous apes, thecalf muscle is profoundly tendinous, facilitating its role as anenergy-conserving spring through running and walking. The exceptionalepidermal, as well as respiratory system of Homo sapiens mighthave advanced in line with habitual walking and endurance racing asancestral Homo secured grip in open surroundings(Strickberger, 2000).
A widely acknowledged bipedalism hypotheses is the notion that humanbeings started walking using rear limbs in place of four, with theattempt of freeing their hands to execute tasks. Evolution researchdemonstrates that primates had historically adapted the opposablethumb from their forelimbs prior to the evolution of bipedalism(Ogihara & Yamazaki, 2001). This permitted primates to grab andhold small objects as other animals were not able to grasp usingforelimbs. The exceptional capability may have resulted in motherscarrying infants or collecting and moving food. It is apparent thatemploying all the four limbs when walking and running restricts thiskind of activities. Carrying food or children using forelimbs wouldrequire the forelimbs are off the ground for prolonged instances. Asearly humans moved to new regions around the world, they mostprobably learned how to habitually walk on two feet, as they usedtheir forelimbs to carry objects like food, and even children(Ogihara & Yamazaki, 2001).
The creation and employment of tools might have as well resulted inbipedalism traced in early human ancestors. Primates had not merelyevolved the opposable thumb, their thinking capabilities and brainshad evolved with time (Richmond, Begun & Strait, 2001). Earlyhumans began to find solutions to challenges in advent manners, whichresulted in their application of tools to assist in making tasks,like breaking nuts or making spears sharper during hunting. Executingsuch works while using tools implies that the forelimbs had to befreed from other activities, like walking or jumping (Richmond, Begun& Strait, 2001). Bipedalism permitted early humans to free theirforelimbs to construct and employ these tools. They were capable ofwalking and transporting the tools, or employing the toolssimultaneously. This was a major benefit as they moved long distancesand formed advent habitats in new regions.
A different hypothesis on the evolution of bipedalism derives fromthe need to see long distances. It is possible that human evolved tobipedalism following their movement from trees and adoption ofsavanna life (Tomkins, 1998). Fossil record depicts that initialbipedal hominines still adapted tree climbing and walked upright.Hominine remnants located in dry grassland surrounding evaluated byanthropologists resulted in conclusions that hominines survived,slept, moved upright. Early humans occupied regions that had untamedgrasslands (Tomkins, 1998). This means the grasses were taller thanthe creatures restricting their capability to see long distances dueto the length and mass of the grass. This triggered primates to standusing their hind limbs. Through standing and walking using rearlimbs, early ancestors almost doubled their heights. Thus, making iteasier to see over the tall grass during hunting, gathering ormovement, this became a very advantageous trait. The capability tosee ahead aided in the location of more food sources and water. Inturn, the primates habitually adopted the standing posture andadvanced to moving using their hind legs alone.
Early humans were not merely hunters rather they were also gatherers.Much of what was hunted was collected from trees as it involvedfruits as well as tree nuts. Because the food could not be accessedthrough use of mouth when walking on all limbs, bipedalism evolutionemerged. Early humans adopted the act of standing upright as theystretched their arms towards the trees, which greatly enhanced theirheight (Tomkins, 1998). It also made it easier for the animals toaccess and single out low hanging fruits and nuts. According to theposture feeding hypotheses, chimpanzees employed bipedalism throughgrabbing fruits from overhead branches (Strickberger, 2000). Thebipedal movements might have evolved into habitual behaviors, as theywere so suitable when reaching out for food. It is also possible thatbipedalism evolved through chimpanzee arm hanging, which wasefficient in food harvesting. When assessing fossil structure,Australopithecus afarensis have alike shoulder and hand traitsto those of chimpanzees, depicting arm hanging. Additionally, theAustralopithecus rear and hip limb depict bipedalism. Thefindings result in the conclusion that the evolution of bipedalism ismore associated with feeding position than walking posture(Strickberger, 2000).
The evolution of bipedalism also links to enhanced reproductivesuccess. Research depicts that bipedalism allowed adult males toconvey food manually to their children and females (Strickberger,2000). This means that the children and females remained in onelocation. The method of provision minimized the requirement forfemales to be progressively mobile in searching for food. It resultedin relevant benefits: a somewhat stable home, which availed moresteady social associations and probably closer mother-infantassociations in turn improving offspring survival. Another benefitinvolves minimal harm to infants due to reduced attachment to amoving mother. The male that left in search of food would returncarrying the food using forelimbs and walking with hind limbs. Inturn, females and children copied the walking behavior.
Bipedalism is still evolving. Even small alterations as a generalalteration in average height in the previous 100 years may beemployed to depict adaptations are accruing, which will result inspecies evolution (Strickberger, 2000). It is possible to assume thatbecause we do not see the changes in humans, then there is noevolution. When arguing evolutionarily, it is necessary to bear inmind that evolution becomes apparent after long periods. 100 yearsmight appear as a long period because few human beings live for thatlong. The available evidence employed in demonstrating the evolutionof bipedalism relies on research conducted on human species datingthousands of years ago. This implies that it is impossible tophysically show that evolution is happening. It is not possible tosee the alterations through our lifespan. However, years later it ispossible that subsequent generations will witness the evolution inbipedalism.
Lewin, R., & Ebooks Corporation. (2005). Human evolution: Anillustrated introduction. Malden, MA: Blackwell.
Ogihara, N & Yamazaki, N. (2001). Generation of human bipedallocomotion by a bio-mimetic neuro-musculo-skeletal model. BiologyCybernetics 84(1), 1-11.
Richmond, B. G., Begun, D. R & Strait, D. S. (2001). Origin ofhuman bipedalism: The knuckle- walking hypothesis revisited. AmericanJournal of Physical Anthropology 116(33), 70- 105.
Strickberger, M. W. (2000). Evolution. Sudbury, Mass: Jonesand Bartlett.
Tomkins, S. (1998). The origins of humankind. Cambridge,England: Cambridge University Press.