Bipedalism Research Paper

It has long been believed that humankind owes its survival to bipedalism, which is the ability to walk on two legs. This is the first human characteristic to distinguish human from other primates. It is habitual, meaning that it is the primary form of transportation. This characteristic thrived in a time where forests were shrinking and the environment consisted of grasslands. The feature bipedal locomotion leads humans to manipulate their surroundings, bypassing their biological features and being given to the ability to live anywhere, and in any environment. Although developing into bipedal organisms hominids were taking a big gamble. With all the benefits of bipedalism, there are also many disadvantages. In some cases these disadvantages

have caused a set-back for humans, even causing many deaths. Was this human characteristic a failure of natural selection?

And would a human has better benefited if their early ancestors followed the way of the modern chimp and stayed quadrupedal. Bipedalism, as an evolutionary advancement, poses new advantages and disadvantages to the survival of mankind.

The greatest benefit to bipedalism is that it leaves the hands open to carry “objects such as food, tools, offspring, and weapons” (Jablonski and Chaplin 113). This is quite prominent considering advances in tool-making and weaponry gave hominids an advantage over other predators that just depended on their own body to hunt. This is an advantage, because when it come to certain tasks humans can invent a new tool that is better suited to accomplish that task. For example, if a predator was ripping meat off the bones of its prey it wouldn't be able to successfully remove all the meat from the animal. A human, with the use of their tools, can

effectively remove more meat from the animal; they could also remove other parts of the animal that would be useful to them, such as the bones or hide that would also be beneficial for their survival. Having their hands free would also allow them to carry and feed young children. This is essential as other “primates are highly developed at birth, [while] human babies are born helpless” (Roberts and Thorpe 283). This child’s helplessness is combated by the mothers beneficial ability to be able to carry her child, feed it, and still be able to move around. Hands could also be left free in order to exchange social communication, such as hugging or patting each other on the back (Jablonski and Chaplin 116). Communication through body language was key in a time that could have lacked verbal communication. Body language as the main source of communication it is fair to say that this could have been used in constructing social group. It brought people together, and by living in small bands and tribes hominids increased their chance of survival, as now they had multiple people gathering food and protecting each other.
Hominids populations resided in areas which were “composed largely of open wooded grassland” with “food and water resources [that] were not evenly distributed” (Jablonski and Chaplin 116). One beneficial adaptation of bipedalism is the locking knee. Having the feature of a locking knee meant that less energy was used when moving from place to place, allowing hominids to travel longer distances (Bill 2016). This allowed for a greater chance of survival, instead of hunting, hominids were able to follow an animal until it tired out, in order to kill and eat it, or walk further distances for water and better living conditions. Another benefit of the locking knee is that it put less stress on the joints (Bill 2016). This meant that walking around for a longer period of time wasn't as painful as it would be for other species who didn’t possess this feature.
With resources being so scarce and spread out, there was increased competition between primates. Bipedalism appeared more frequently in “pre-hominids… then they did in other hominid lineages”, therefore, it was used as a “dominance appeasement” (Jablonski and Chaplin 116). This was extremely important as it allowed hominids to settle problems within groups in a peaceful way, instead of using aggression and violence. Ergo, bipedalism was used as a mechanism to settle “dominance between group members of both sexes over food and water that would have occurred in high frequencies in an open environment” (Jablonski and Chaplin 116). By resolving problems in a constructive way, it became more ritualized and less likely for a member of the group to get hurt in the process. This is in contrast to great African apes, who had a high mortality rate due to inter-group conflicts (Jablonski and Chaplin 117). This ability to be able to resolve conflicts in a ritualized, peaceful manner allowed for a succession of hominids over other primates and allowed more of them to be alive to gather resources.
Bipedalism also advanced the hominids thermoregulation system, by minimizing the body’s contact with sun rays. This caused a huge advantage when walking through the savannah heat. In fact, experts have argued that in conditions like the savannah where “solar radiation [is] high and there is a high risk of hyperthermia and where there may have been a need to collect food constantly, from sunrise to sunset” (Jablonski and Chaplin 114). By walking bipedally exposure to sunlight would be limited to the top of the head. This would create a shield to the rest of the body. Keeping the body away from a direct heat source would allow the rest of the body to be exposed to the cool winds and breezes. This allows them to keep the overall temperature of the body comfortable enough to be able to gather food the entire day giving them an advantage over quadrupedal primates, who suffered in extreme heat on the savanna.
With many advantages that aided in the evolution of hominids, bipolarism also caused disadvantages by decreasing their speed. Hominids had “significantly larger legs in relation to its body” (Aiello and Wells 331). Quadrupedal animals, who had shorter legs, also had more limbs helping them move. When moving short distances quadrupedal animals could move faster. It was seen that “at maximum running speed, human bipedalism is twice as expensive energetically than estimated for a quadrupedal mammal of the same body mass (Aiello and Wells 332). The posed a benefit for quadrupedal animals when it came to hunting. Quadrupedal animals that possessed this speed could chase and capture their prey. Hominids would have most likely gotten to the animal after the quadrupedal animal had already killed it and eaten part of its meat.
Lastly, the biggest disadvantage that bipedal hominids, compared to other primates can be seen when looking at childbirth.

Human babies are helpless at birth compared to other primates and depend on their mother for a long duration of time. This is because they are born at an earlier “stage of neurological and cognitive development,” a result of having only 30% the brain size at birth compared to Chimpanzees with 40% (Roberts and Thorpe 283). The pelvis of a bipedal walker does not allow for the birth canal to be wide enough for a bigger brained baby to go through. Later humans have gone through adoption such as “absolute increase in coronal width, and a relative increase in sagittal depth” in order to give birth to big-brained babies (Roberts and Thorpe 284). This would have been big problems for early hominids as it would mean that giving birth to a baby would be a lot harder because of this compared to other primates with a larger birth canal. Without proper help the rate of both mother and child dying at birth was high. Also, because the child was so dependent on the mother in created a handicap for her, she herself would need some sort of extra protection from another hominid. This can be thought to be essentially early forming of a basic family unit. Finally, anything was to happen to the mother, the chances of the baby surviving on its one would be little to none. Unless another member of the community was to take over and care for the

child.
It is fair to say that the sacrifices were high for all the benefits that came with bipedalism.Bipedalism decreased the speed of hominids, created inconveniences in hunting and being hunted, and negatively affected child birth. However, bipedalism allowed for hominids to be able to survive in the heat of the African savannah. If they had continued walking quadrupedally while not having the shield of shaded forested landscapes; they risked the chance of dying from hyperthermia or dehydration. By being able to travel around at a time when the sun was at it hottest they were able to gather more food. This gave them an advantage over other primates that would have to wait until the later afternoon before searching for food. Travel longer distances without getting tired, allowed them to travel to different environments, at some point even leaving Africa, to improve their standard of living. Bipedalism allowed for technological advancements, which allowed for proper tools to be able to hunt animals for their meat. This meat fed their brains, and this resulted in bigger brains that developed more complex and intricate thoughts. The complex thoughts eventually transformed into the lives that humans live today. A human can now virtually live and survive anywhere on planet earth and even space. It is safe to say that all the advantages of bipedalism far outweigh the disadvantages, therefore, bipedalism is a huge win for natural selection and mankind.