Human evolution suggests a linkage between man and the apes through an apelike ancestor that lived a million years ago. The proposed theory visibly state that humans advance as to what we are today by mutation and genetic factors and leaves the apes to evolve in a separate path. Charles Darwin (1809-82) who became famous because of his contributions to this theory wrote the book, The Origin of Species. Today, the accepted theory of evolution depends on three concepts.
These concepts simply give various explanations as to how humans evolved for millions of years by focusing on the capacity to pass on the genetic information.The first principle, microevolution, believes that mutation occur naturally in man due to environmental factors. There is an occurrence of error in these mutations due to radiation or chemicals. Another belief is the survival of the fittest or elimination of the weakest also known as natural selection. Those creatures that continued to exist have the chance to pass on their traits, while other species unable to compete in the wild experience die off. Lastly, mutation can take place because of the inability of certain species to propagate with other species.
This belief is called speciation where seclusion from the previous community comes about. Although these beliefs are still applied to make conclusion on other studies, new evidences and debatable facts disrupt the credibility of this theory. For example, the evidence regarding homology, which explains that if two are alike, they are related. Some skeletons of apes and humans, which have high resemblance in terms of physical appearance, do not necessarily mean they are related. Current studies show that similarities can take place even though they have different sets of DNA.
In evolutionary terms, this principle is called convergence. In addition, another evidence, which is the fossil records, implies questionable integrity because of the so-called missing link still absent in the records up to now. Even if human evolution depicts signs of incredibility, scientists do not refute this idea. Human evolution, as evidences show, can be affected by behavioral or environmental factors.
(allaboutscience. org, 2007) Behavioral Factors The ability to move on two feet or bipedalism is a vital characteristic seen on hominids.Ardipethcus ramidus and Lucy ¬illustrated this trait with a proof of fossils showing two footprints dating 3. 7 million years ago at Laetoli, Tanzania. In addition, skeletal remains provide a more reliable evidence of bipedalism in earlier hominids.
Physiological aspects of bipedalism seen in Homo sapiens are the position of the foramen magnum or the hole at the base of the skull; a thicker, rounder pelvis; a femur angled towards the midline of body and feet aligned correctly. Bipedal locomotion gives the hands the opportunity in handling and transporting food.Moreover, savanna-living animals feel more comfortable because a stand-up position decreases the surface area of the body exposed to the sun. (Zarpour, 2002) C. Owen Lovejoy presented another principle of bipedalism called the Provisioning Model that concentrates on social behavioral means that is vital to birthrate and survivorship. Sexual relations of hominids seem to be monogamous that needs male provisioning.
Food transport by males to their mates and infants progresses bipedalism in order for them to protect their child from hunger and increase propagation.Subsistence or the ways in obtaining and distributing food of early humans and can be affected by social behavioral traits. One such way is the food-gathering hypothesis where there is an evident sharing and collaboration between each members of the group. There are some evidence showing in old archeological sites showing stone tools and food. These places are called home bases where features like sharing of food between couples that are part of a social hunter-gatherer campsite.
Conversely, through a more in-depth study of this hypothesis they ended up questioning it because of microscopic investigation of animal bones revealing tooth marks of carnivores and human tools thus suggesting scavenging. (encarta. msn. com, 2007) Behavior concerning tool making was first analyzed in chimpanzees. This is a study considered because of relative size of brain of Australopithecine (370 and 515 cc) slightly larger than the brain of a chimpanzee.
Some observations done on chimpanzees illustrate utilization of stone and wood as hammers to crack nuts and weapons for hunting small animals.Complex examples of chimpanzee tool are small, slender tree branches from which they detach from trees. They use these kinds of tools for their favorite food-- ants and termites hiding in holes of trees. Although chimpanzees are compared to Australopithecines, a well-known descendant, the Homo habilis better known as “handy man” gave more efficacy and sophistication on stone tools. This resulted from their advanced intelligence demonstrated by an 800 cc brain size.
(O’Neil, 2007) The discovery of fire by man is still studied today. Nonetheless, one truth in this discovery is accident.Early humans could not have thought of fire as we are thinking today, rather, fire was evidently used by other animals and is imitated by man. Birds during forest fires see prey and hunt them down. Soon after, land animal predators seek burnt meat after a forest fire for ingestion.
Salt content in burnt soil attract bovines and deers. Significantly, mammals derive heat from after forest fire locations. With humans having a perceptible intellect, joined these animals in their exposure to fire. Hence, man participated in fire’s beneficial use in food and warmth accidentally.
(beyondveg. com, 2007)Environmental Factors Dr. Kevin Hunt’s hypothesis on bipedalism indicates the effect of ecological factors. He created the Postural Feeding Hypothesis that point out bipedal locomotion as a habitual action because of the need to adapt in food gathering. Skeletons of early hominids such as Australopithecines give emphasis to arboreal adaptations as long forelimbs seen imply food access and facilitate arm hanging.
Another hypothesis, the Thermoregulatory model indicates adaptation to the environment. Unlike Hunt’s hypothesis, Wheeler presumed bipedalism to be an effect of major climate change.When an organism walks on two feet, a cooling mechanism due to greater wind exposure of the body happens. Same with Wheeler’s theory, Vrba’s Turn-Over Pulse indicate pressure on these creatures to develop bipedalism for the reason of heat dissipation.
Evidences show that in the beginning of Pliocene period around 2. 5 million years ago, drier conditions and decreased wooded habitats showed on fossils and soil texture support Wheeler and Vrba’s postulates. (Jacobs, 2000) Subsistence of early humans in connection with environmental factors has something to do with cold temperature.In order for these humans to adapt in a cold atmosphere, they have to obtain meat and fat proteins. The two major arguments are hunting and scavenging.
Proofs of hunting of early humans are found in cold areas like Boxgrove, England where 500,000 years ago, fossils indicate humans catching a group of animals between a watering hole and the side of a cliff then slaughtered them. Scavenging or taking carnivores’ leftovers, on the other hand, have been developed by scarcity on food due to increased meat consumption.An evidence of fossils collected on an old archeological site containing bones with tooth marks of carnivores and marks of cutting tools suggest scavenging of early humans. In addition, current excavations at Olorgesailie, Kenya, reveal that Homo erectus cut meat from elephant remains. (encarta.
msn. com, 2007) Tool making of early humans depend on how it will be used. Primarily, tool making involved the materials that are to be used for greater efficacy. Such as the Oldowan tools discovered by Mary and Louis Leakey connected with Homo habilis at Olduvai Gorge, Tanzania.These tools are made from hard water-worn creek cobbles made out of volcanic rock.
These creek cobbles are usually knocked-off when hit by another rock. Thus, a jagged chopping or cleaver-like implement performed as multipurpose hammering, chopping and digging utilizations. Due to meat consumption, there are also Oldowan tools for slaughtering animals in the form of sharp-edged stone tools or flake tools. On the other hand, Acheulian tradition discovered at Saint Acheul site, France first arise in East Africa.
Hand Axes were the most vital tools in the Acheulian tradition.Usually made of hammerstones, functions of hand axe include chopping of wood, butchering animals and cracking nuts or small bones. (O’Neil, 2007) The use of fire with the influence of environment occurred in cold temperate regions and of warm places where forest fires can take place. The most popular evidence of the latter is at Swatkrans, South Africa and Chesowanja, Kenya where soils in these places reveal exposure to high temperatures.
However, it is still discussed if it is caused by a wildfire or human-made fire.Forest fires often leave the area barren and meat of animals burnt. This gave a sweet-smelling scent and early humans’ discovery of the contribution of heat to a longer shelf life. The Zhoukodian cave in China, where Homo erectus inhabited, shows the use of fire in caves and signs of cooking brains of animals as early as 500,000 to 1. 5 million years ago.
(beyondveg. com, 2007) Summary Man’s evolution has several evidences such as fossils revealing lifestyle, skeletons depicting locomotion and brain size and contributing facts of the environment.Such theories on bipedalism and subsistence outwit each other through current discovered fossils. On the contrary, tool making is proven enough by each site of finding and materials used. The function of every tool is revealed on the structure and appearance of each while the discovery of fire is attributable to accidental exposure.
Almost all facts about human evolution is still questionable but the important things in solving all these arguments are the reliable facts.Bibliographyhttp://www.allaboutscience.org/evolution-of-man.htmhttp://www.abouthumanevolution.net/html/lesson1.htmhttp://www.jqjacobs.net/anthro/paleo/bipedalism.htmlhttp://www.beyondveg.com/nicholson-w/hb/hb-interview2c.shtmlhttp://anthro.palomar.edu/homo/homo_3.htm
