Characteristics of Australopithecines - Essay Example

Australopithecines The word "hominid" refers to "any of a family (Hominidae) of erect bipedal primate mammals comprising recent humans together with extinct ancestral and related forms" (Merriam Webster). Hominids are included in the super-family of apes, the Hominoidea, in which the members are referred to as hominoids. Though the fossil record of hominids is currently fragmented and incomplete, there is enough material present to provide a healthy sketch of the evolutionary history of homo sapiens. Inasmuch as the Australopithecines were "bipedal primate mammals," they can be classified as ancient hominids (Merriam Webster). Many changes in the physical environment contributed to the evolution of these early humans. Australopithecines comprise a genus of primitive hominids that resided in Eastern Africa about 4.2 million years ago. Many scientists think that some of the australopithecine species are direct ancestors to humans. Others believe that the Australopithecines represent a branch of hominids from which humans evolved, but are not directly related to humans. There several established taxonomic methods for classifying the australopithecines, but the four most frequently acknowledged species are Australopithecus afarensis, Australopithecus africanus, Australopithecus robustus, and Australopithecus boisei (Chardin). The species can be differentiated, because A. robustus and A. boisei have bigger bones and are more "robust" than A. afarensis and A.africanus (O'Neill). Most species of the Australopithecus were not any more adept at using tools than modern primates. But, Australopithecus garhi seems to have been the most sophisticated, because its remnants have been discovered near tools and slaughtered animal carcasses, which suggests the advent of a highly antediluvian tool conception. This caused many scientists to infer that A. garhi must be the predecessor of the Homo genus, even though recent deductions held that A. garhi was merely competition to the ancestral Homo species. The brains of most Australopithecus species were barely 35% the size of the modern human brain (Foley). Most species of Australopithecus were small and gracile in nature, often standing no more than 1.2 meters in height (Wikipedia). Fossil records seem to indicate that Australopithecus is the ancestor of a specific classification of hominids, known as Paranthropus, but are not direct ancestors of the genus Homo, which encompasses modern humans. Both the Paranthropus and Homo genera have proven to be more progressed in behavior and customs than the Australopithecus, which were hardly more than bipedal chimps. It is still widely accepted that only the descedants of Homo would go on to generate language and learn how to use fire. Though opinions certainly vary in regards to whether the species aethiopicus, boisei and robustus should be placed within the genus Australopithecus, the scientific community currently places them in the genus differ as to whether the species aethiopicus, boisei and robustus should be included within the genus Paranthropus. Paranthropus is thought to have originated from the Australopithecus lineage. Until recently, many scientists classified all Australopithecus species within a single genus. Paranthropus, because it was larger and more robust, was physically different from Australopithecus, and its superior anatomy implied that its behaviors might have been very different from that of its ancestor. The more diminutive and gracile forms such as Australopithecus africanus and Australopithecus afarensis are commonly assumed to be the closest relatives to humans. But, some studies have shown that Australopithecus africanus had a body shape more similar to that of the modern apes than to the members of the genus Homo. Still, the gracile australopithecines are considered to be the earliest known true hominids, because australopithecines and humans are biologically similar enough to be classified in the family Hominidae (Nickels). Australopithecines and humans likely evolved from the same ancestors on the African continent. Both have reasonably large brains. And, both are habitually bipedal organisms that walk on two feet. In contrast, chimpanzees and gorillas are mostly quadrupedal, four footed, walkers. This is quite interesting when one considers that approximately 3 million years ago when the australopithecines were evolving in East and South Africa, the African forests were gradually diminishing. Grasslands and savannas were becoming more common throughout the continent, and bipedalism would have certainly been an advantage in this type of environment. Ultimately, there were most likely two evolutionary lines of the early hominids (Johansen and Edy). One line would have been primarily adapted to grassland environments and would have had a diet that was predominantly omnivorous and consisting of meat. This line would have constituted the ancestors of humans. The other line most likely inhabited grass and woodland habitats and would have been mostly vegetarian. It is very likely that most of the early hominids, including the humans, augmented their diets with protein and fat-rich termites and ants (Stanley). The most notorious specimen of Australopithecus, known as "Lucy," belongs to the A. afarensis species. A. afarensis was first discovered in East Africa and provides a lot of fossil information regarding the morphology of the early hominids (Johansen and Edy). The A. afarensis possessed characteristics that fell between the hominids and chimpanzees. Some of these characteristics included sub-nasal prognathism (facial projection), canine size dimorphism, diastema, endocranial capacity similar to that of chimpanzees, compound temporal-nuchal crests, saggital crests, and V-shaped dental arcades (Foley). These same characteristics are widely expressed among the later Australopithecines species. Australopithecine modes of locomotion have long been a point of contention, often centering around the formation of the australopithecine pelvic and knee bones. The early studies seemed to show that the australopithecine pelvis was an apparent precursor of the Homo pelvis, because it had human-like bipedal characteristics. But, later studies of australopithecine locomotion found it to be decidedly different from that of modern apes, but also quite different from humans--a seemingly separate and distinct mode of locomotion. Today, the general consensus concludes that the australopithecines were probably adapted to both climbing trees and at least semi-upright walking. This gives australopithecines a form of locomotion distinct from all early primates, humans, and even modern apes. In any event, the confirmed existence of Australopithecus seems to have put to rest the theory that human intelligence evolved first and bipedalism followed, because Australopithecus had a brain case that was not significantly larger than that of a modern chimpanzee. But, Australopithecus was definitely bipedal, and this suggests that bipedalism preceded human intelligence rather than the other way around. There is little doubt that Australopithecines constitutes a group of extinct hominids that are quite closely related to humans, because they have proven to be bipedal primates. However, the Homo genus either split from the Australopithecus genus at some point or both of them emerged independently from an unkown common ancestor. Changes in the physical environment heavily contributed to the evolution of early hominids. With the disintegration of African forests in the South and Eastern continent and the new emergence of grasslands, it benefited early hominids to acquire bipedal locomotion. The changes in the environment would also explain the Australopithecus adaptations for climbing and walking upright on two legs. Works Cited Chardin, Pierre Teilhard. Status of Australopithecines. On the Zoological Position and the Evolutionary. New York Academy of Sciences. 1952. http://www.clarku.edu/piltdown/map_gen_hist_surveys/status_austral.html D.C. Johansen and M.A. Edey. Lucey: The Beginnings of Humankind. 1981. E. Delson Edition. Foley, Jim. Fossil Hominids. 1995. http://www.snowcrest.net/goehring/a2/primates/fossils.htm In Hand Museum. Australopithecus. 2005. http://www.inhandmuseum.com/LA/aust.html Iscid Encyclopedia of Science and Philosophy. Australopithecines. 2005. http://www.iscid.org/encyclopedia/Australopithecines Merriam-Webster Online Dictionary. 2005. Entry: Hominid. http://www.m-w.com/cgi-bin/dictionarybook=Dictionary&va=hominid Nickels, Martin K. Creationists and the Australopithecines. National Center for Science Education. 1998. http://www.natcenscied.org/resources/articles/623_issue_19_volume_6_number_3__5_28_2003.asp O'Neill, Dennis. Discovery of Early Hominids. 2005. http://anthro.palomar.edu/hominid/australo_1.htm Stanley, Steven M. Climatic Forcing and the Origin of the Human Genus. John Hopkins University. National Academy of Sciences. 2005. http://www.nap.edu/books/0309051274/html/233.html Wikipedia. Australopithecine. 2005. http://en.wikipedia.org/wiki/Australopithecus Read More