The Presence of Hominids in Africa - Essay Example

Exploring Physical and Biological Anthropology Exploring Physical and Biological Anthropology The family hominidaeor hominids belong to the superfamily hominoidea which, as the fossil evidence suggests, were thought to exist in the Great Rift Valley of East Africa. The hominidae mainly comprise of humans and our extinct ancestors. As the fossil evidence found advocates the presence of hominids in Africa, the climatic changes occurring during that era greatly affected the evolvement of these species. One of the major characteristics that were influenced was locomotion, which primarily comprises of progression to bipedalism. The first signs of development of bipedalism were seen during the late Miocene (10 – 5.5 Million years ago) and early Pliocene (9.5 – 4 Million years ago). During this period essentially nine to seven million years ago, the African rainforest reduced in size, causing wide spaces, patches of bushes and riverine landscapes to appear. Thus the area transformed to mainly savannah than tropical rainforest. Some anthropologists suggest that due to presence of water bipedalism was influenced, as in water standing upright favors movement rather than on four feet. This also helped the hominids to bring food to the bank using their hands. Since the density of the rainforest had reduced, there was more sun exposure; therefore bipedalism also favored reduction in surface area exposed to light. Standing in upright position also enhanced the ability to see over tall grasses and improved predator prevention. The fossil evidence for bipedalism is fairly evident from the skeleton of an afarensis female (Lucy) originate at Afar in Ethiopia in 1974; a species that is believed to walk around 3.6 million years ago (Hall, Hallgrímsson, and Strickberger 509). Around 54 million years ago, marking the beginning of Eocene era, as the climate became cooler and drier influenced the replacement of mammals of Paleocene by the placental mammals counting primates. Adapoidea and Omomyoidea were the two main superfamiles that evolved and faced decline during the Oligocene. The fossil record suggests anatomical changes which help us verify that these living creatures acquired complete features of primates. Adapoids and omomyoids further gave rise to strepserhines (lemurs and lorises) and haplorhines (tarsiers, monkeys and apes). After the strepserhines and haplorhines split, in the late Miocene the generalized monkeys emerged which are considered to give rise to the higher primates. At the beginning of the Oligocene, a drastic cold spell resulted in extinction of many species and appearance of new ones which included monkeys, although fossil records indicate emergence of monkeys during late Eocene. At the beginning of the Oligocene the lineage split into platyrrhines (New World Monkeys) and catarrhines (Old World monkeys, apes and humans). The early hominoids developed into the Apes, who diversified during the Miocene era (Melissa 9). The fossil evidence also suggests existence of African Apes during the mid of Miocene. Anatomical changes occurred as the posture and walking position changed during evolution of bipedalism. These changes included the curvature of the spine. A quadruped had more of a C shaped spine as compared to a bipedal who had alternating convex and concave curvatures which gave the spine an S shaped appearance. This, and the attachment of spine to the bottom of the skull, helped bring the centre of gravity towards the hip and ultimately serving the two feet stature. Fossil evidence was found in Europe of Oreopithecus (12 million years ago) suggesting upright posture and bipedalism with a more flexible spine (Filler and Pilbeam 252). Second, the pelvis evolved into a basin shaped structure which sustained the abdominal organs. To prevent tripping in front, the gluteal muscles were well developed. The anterior gluteal muscles made standing on one leg possible by supporting the Ilium. Thirdly, to support the weight of the body the distil ends of femur (thigh bone) and the tibia (calf bone) were enlarged to form condyles. Fourth, the foot was formed from three types of bones along with arches which served as weight bearers and shock absorbers. The foot bones are attached by strong ligaments to maintain the overall motion of the foot while walking. Lastly the anatomical changes in the arm benefitted the bipeds as well. Walking on two feet excluded the arms from locomotion and thus underwent anatomical changes which served them to carry out tasks for tool making and carrying load. The opposition of the thumb developed which allowed the hand to hold objects. The three evolutionary models which elucidate bipedalism include social behavior, feeding and posture to benefit thermoregulation and energy efficiency. The theory of social behavior suggested mating benefits and standing in upright position to show authoritative display. As suggested by the model presented by C. Owen Lovejoy, the slow hominid reproduction rate might have contributed to the eventual evolution of bipedalism which favored mating. The second model suggests usage of forelimbs for feeding purposes carrying tools and infants rather than locomotion contributed to bipedalism. (Klenerman, Wood and Griffin 36). Standing on two feet to reach fruit trees contributed to this evolution. Additionally, patchy food availability required males to travel far and carry food for their females back home using their forelimbs, which also improved energy efficacy. Thirdly walking on two feet served as a more efficient method to travel than on four feet which requires greater oxygen consumption. Furthermore, upright posture presented less surface area for the sunlight to fall. Plus, standing tall above the ground improved heat dissipation and helped in keeping body cool. These models suggest different reasons why bipedalism evolved, but the main similarity between them is that each of these models supports the adaptation of the hominid for survival of species and to counter the changes in environment. The main difference between models is that each of them has an impact on a separate segment of life, for example one model deals with more social issues while other deals with nutrition or energy conservation. In my opinion, the social model supports the evolution more since the institution of family has always promoted changes in species further suggesting the importance of reproduction for the continuation of species. Neandertal burial behavior has been confirmed by almost 35 Neandertal skeletons found (Schrenk, Müller and Hemm 86). One major example is of the spy skeletons found in Belgium in 1880’s, in which skeletons were found completely intact at the joints. At some instances personal items such as animal teeth were also found alongside the body suggesting that it was mainly a purposeful burial. Other fossils found in Iraq, France and Uzbekistan showed complete body burial further supporting burial behavior. Subsistence strategies mainly included methods for hunting of food which is supported by the animal remains in Kebara, Israel. Also, the discovery of burned bones indicates that food was cooked for nourishment. Little proof has been found of scavenging activities. However evidence has been found of possible cannibalism being practiced. Fossils found in Krapina, Croatia indicates cannibalism due to the present of no intact long bones which suggests that the bones might have been slit for the bone marrow. Additionally the Neandertal fossils, found in Moula-Guercy, show abundant marks on body and broken cranial and long bones to obtain the brain and marrow. Neandertal fossils have shown more connection with Middle Paleolithic tools which included bone or antler tools. Also the tools developed were based on past tool cultures which were modified to their own needs. In terms of cannibalism, in modern humans it is a rare practice now. On the contrary hunting techniques are still widely practiced but have also been replaced by cattle breeding. Basic behavior was common to both Neandertals and modern humans, which is to survive. The Old World consists of the Europeans, Asians and Africans. Modern H. sapiens fossils have been found in Herto and Omo in Ethiopia aging 150,000 years and are very similar to the modern human. Later in South Africa and Ethiopia fossils bearing complete resemblance have been discovered, indicating presence of well established H. sapiens. In Europe, fossils of humans have relatively appeared late around 40,000 years. Fossil records have been found in Romania, Czech Republic and France; the best early H. sapiens being found in France. In Asia, fossils of anatomically modern humans have been found in China aging 65,000 years. Early H. sapiens records have also been found in Borneo and Indonesia. There are two models that attempt to explain the origins of the modern human. The replacement model asserts that all humans have a common place of origin: Africa. It is bolstered by the evidence from DNA and the fossil records. The oldest fossils that have the most resemblance to the current human were found in Africa; moreover, Africa has the most varied genetic makeup present within its population and this genetic diversity can account for the fact that all humans trace their origin back to Africa. On the other hand, the model does not provide a perfect explanation for the genetic diversity present. The betaglobin gene is present in Asia, but is absent in Africa, so the entire human race can not have its origin in Africa. Also, the model considers the rate of mutations to be constant, whereas it is not; for instance the Y chromosome has faster mutation rates compared to other genes. Conversely, the multiregional model, or the regional community model, argues that all humans have their origins in key regions of the Old world, and have evolved from those particular areas. The model also adheres to the notion that there was genetic flow that maintained diversity. This model is a better fit to the current fossils evidence since the fossil records are suggestive that the current and archaic habitants of a certain region have common anatomical features which people of other regions do not share. East Asians have shovel-shaped incisors, resembling their ancestors Homo eructus, which Europeans do not have. The Chinese resemble Jinniushan people who lived over 200,000 years ago. Neandertals and the Europeans are similar in their high brow bridges and aquiline features. Therefore, the multiregional model is a better fit. Works Cited Hall, Brian Keith, Benedikt Hallgrímsson, and Monroe W. Strickberger. Strickbergers evolution: the integration of genes, organisms and populations. Mississauga: Jones & Bartlett Learning, 2008. Print. Filler, Aaron G. and David Pilbeam. The Upright Ape: A New Origin of the Species. New Jersey: Career Press, 2007. Print. Klenerman, Leslie, Bernard A. Wood and Nicole L. Griffin. The human foot: a companion to clinical studies. USA: Birkhäuser, 2005. Print. Schrenk, Friedemann, Stéphanie Müller and Christine Hemm. The Neanderthals Peoples of the ancient world. Oxon: Taylor & Francis, 2008. Print. Stewart, Melissa. New World Monkeys Nature Watch. Minneapolis: Lerner Publications, 2007. Print. Read More