Evolution Essays - Biological Evolution, Evolutionary Biology

Evolution The origins of mankind is an extremely controversial issue within today's society. Scientists have a host of different theories pertaining to man's inhabitance of earth. Many disagreements arise between scientists who have different beliefs pertaining to where and how mankind arose. One such argument is the conflict involving the theory of evolution versus the theory of creation. After extensive scientific research, it is apparent that the theory of evolution is correct. Evolution is the theory that life arose by natural processes at an early stage of the earth's history and that complex organisms developed from simpler organisms by a process of slow change (Coren 209). It's the idea that new species arise from older species after thousands of years of gradual chemical, environmental, and genetic change (Coren 142). Evolution can also be described as the complex processes by which living organisms originated on earth and have been diversified and modified through sustained changes in form and function (?Evolution?). Scientists, looking for an explanation to the origin of man and other organisms created this evolutionism theory, which also presented answers to the many asked questions dealing with similarities between species. Unlike the theory of creation, which states that the complexity of life and different species can only be explained in terms of a supernatural creator or god who placed life on earth, the theory of evolution has a plethora of evidence proving it to be true (?Creation?). There are several different types of observations that support the theory of organic evolution as an explanation for the similarities and the differences among species. One such observation is in the geologic record. The geologic record is the rock scheme found within the earth's outer crust. By means of radioactive dating, the ages of rocks in many places on earth have been determined. It's a timetable of the earth's geologic history. This combined with the fossil record, another observation supporting the evolutionary hypothesis, has produced an apparent sequence of life forms from most simple to most complex during the history of the planet. Fossils are any remains or traces of a once-living organism, which are formed by preservation, petrifaction, or sedimentation. Organisms can be preserved and protected against decay by being trapped in amber, tar, or frozen in ice. The hard parts of an organism, such as shells or bones, can be preserved when the flesh of an organism has decaye d away. In other cases, materials of a dead organism may be gradually washed away and replaced by minerals from the water causing the organism to petrify, or harden. Imprints, molds, or casts left by an organism after it is enclosed in sedimentary rock and decomposed are also fossils, as well as footprints and tracks. The fossil record is the timetable of fossils found in within the earth's geologic record. Since the upper layers of sedimentary rocks are assumed to have been laid down over lower layers, the upper layers are younger than those deeper into the earth. Therefore, fossils found within the upper layers are also younger than those found within the lower layers. This combination of geologic and fossil records shows the progression of species as time also progressed (Coren 142). In reiterating the definition of evolution, we are reminded that gradual changes in one life form's anatomy, cytology, embryology, or biochemistry could cause for a new species to originate. Similarities in these categories link species together and are therefore studied to support evolutionism. In comparing anatomy, the structures of different organisms often show unexpected similarities. Cell organelles, such as cell membranes, ribosomes, and other structures found within cells, are also similar in organisms of all kinds, showing that comparative cytology can also shows signs of evolution. When comparing the embryos of different organisms, comparative embryology, similarities can be seen in early stages of embryos that are completely different at maturity. Finally, comparative biochemistry, which is the comparing of biochemical compounds, such as amino acids, can also show similarities in species, reinforcing the idea of evolution (Coren 143). As curiosity rose throughout much of the world, scientists began to question the existence of organisms and why some are so alike in so many ways and so diverse as well. Several theories have been proposed in