Bipedalism: The Path To The Future Essay, Research Paper
The Path to the Future
Approximately 4 million years ago a wonderful evolutionary phenomenon was happening in Africa. Early hominids, man’s ancestors, were beginning a giant leap in their evolution. These hominids were moving out of the forest and beginning to walk upright, out on the open plains (Fagan, 98). This change from quadrupedalism was the most significant adaptation that ever happened to these early hominids. It caused many adaptations that make man what he is today. This process occurred in early hominids for many different reasons, each reason helping to perfect the upright walking posture. Bipedalism is thought to have occurred because of changes in environment, feeding habits, thermal regulation, and behavioral mechanisms.
During the time of the late Miocene epoch, about 10 to 7 million years ago the earth was changing. This change caused a fall in temperatures, which resulted in forest depletion, increasing the percentage of open environments in tropical latitudes. Forest depletion made the species that survived the temperature change adapt to become mostly terrestrial. In fact 40 or more extinct primates including hominids had to adapt to a terrestrial life style. Approximately 4 million years ago this change led to bipedalism in hominids because of problems quadrupeds had moving on the ground (Fagan, 98). Bipedalism was much more efficient when the African plains dried up and resources were very scarce. Long distance traveling on the ground was favored by bipeds (Leney, 00).
In 1996 Kevin Hunt proposed a feeding hypothesis on why bipedalism ocurred. It stated that 80% of the time chimpanzees feed, they are exhibiting a bipedal locomotion (Jacobs, 90). This occurs when chimps feed on the fruits of small, open-forested trees and shrubs. When they feed, chimps stand on 2 legs and reach up to the fruit with their forearms. They usually balance themselves on branches or on the ground and hold on to higher limbs in an arm like fashion (Leney, 00). In later years this adaptation evolved to australopithecines who were still arboreal bipedal fruit gatherers. Only when they started to become terrestrial creatures did they adapt to be fully bipedal (Jacobs, 90).
Another cause for the move to bipedalism was suggested by Wheeler in 1991 and it referred to thermal regulation (Jacobs, 90). This theory stated that bipedalism resolved thermal stress on hominids in open equatorial environments and allowed hominids to remain active in the open during the day (Leney, 00). Having bipedal qualities makes the body higher off the ground where cooler temperatures and higher winds are present. This greater amount of wind created less need for sweating to cause evaporation; thus vital body fluid was conserved. Also, direct solar exposure was minimized because the surface area receiving solar rays was less (Jacobs, 90).
In 1981 Owen Lovejoy suggested that behavioral mechanisms were a factor in the switch to bipedalism. This behavioral mechanism helped hominids in reproductive processes. Having the hands free to carry food and other things to the mate and offspring is seen to be a strong selection factor for choosing a mate. Having a such factor helps with reproductive success in a monogamous mating structure similar to what humans have today (Jacobs, 90). When the creature supplied his family with food he was ensuring monogamy. Ensuring monogamy enhanced his survival chances greatly. This also caused shorter breeding intervals which helped give the hominid an advantage over the competition (Rodman & McHenry, 00).
Each one of these causes did not make early hominids bipedal alone. They all worked together to form the perfect combination of qualities to make the species better. Each one timed by evolution to eventually create what our species is today, Homo sapiens sapiens. Bipedalism did not just make hominids walk on two feet, it was the path that started a series of events that helped our ancestors to be better adapt. These adaptations helped hominids to survive to evolve into humans. Bipedalism was truly the path to the future.Honor Code:
Fagan, B. (1998). People of the Earth (9th ed.). New York: Addison Wesley Longman, Inc.
Jacobs, J. (1990’s). The Origin of Bipedalism. Paleoanthropology in the 1990’s [Online]. Available: http://www.geocities.com/archaeogeo/paleo/bipedalism.html
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Leney, M. (2000, October 25). The Evolution of Bipedalism [Online]. Available: http://users.ox.ac.uk/~newc0607/reading/biped.html [2000, October 25].
Rodman, H., & McHenry, H. (2000, October 25). Theories on Why Human Bipedalism Arose [Online]. Available: http://anderson.cioe.com/~hamilton/page2.html [2000, October 25].