Evolution Essay -- essays research papers

Charles Darwin had two great themes in "On the Origin of Species" which accounted for the similarities and adaptations characteristic of living organisms. To account for the adaptations of organisms and those innumerable features that equip them for survival and reproduction, Darwin (and Wallace) independently came up with the central theory of evolutionary process: natural selection. Natural selection gives insight in to why organisms are the way that they are. Adaptations are phenotypic variants that result in the highest fitness among a specified set of variants in a given environment. In reference to humans, there are many traits that have been selected and adapted for throughout their evolutionary history giving them the characteristics that they have today. In this paper I will discuss some parts of the human body, which have been found to be selected for by the evolutionary mechanisms of natural selection, adaptation and mutation. Natural selection, adaptation, and mutations are three components of the evolutionary process, each one having either positive or negative effects on the other. What exactly is natural selection? There are many variations of the definition but most agree that it must include the following concepts: some attribute or trait must vary among biological entities, and there must be a consistent relationship, within a defined context, between the trait and one or more components of reproductive success, where "reproductive success" includes both survival and the reproductive processes themselves (Futuyma, 1998). Charles Darwin's theory of natural selection states "if variations useful to any organic being ever occur, assuredly individuals thus characterized will have the best chance of being preserved in the struggle for life; and from the strong principle of inheritance, these will tend to produce offspring similarly characterized." Regardless of how it is defined, natural selection and its action can have tremendous effects on the members of a population. It is natural selection that causes adaptation, and these adaptations evolve to ensure the survival of a species. Evolution, in a very broad sense, is defined as descent with modification and often with diversification (Futuyma, 1998). Darwin's idea of evolution was that it occurred by descent with modificatio... ...-carbohydrate, high protein diet. Certain metabolic adaptations were therefore necessary to accommodate the low glucose intake. Many indicate that the adaptive response to the low carbohydrate intake is insulin resistance(Miller, Colagiuri, 1994). A study done by J.C. Brand Miller and S. Colagirui proposes that insulin resistance offered a survival and reproductive advantage during the Ice Ages. This study also proposed that a carnivorous diet would have disadvantaged reproduction in insulin-sensitive individuals and positively selected for individuals with insulin resistance. Another factor mentioned was the various environmental factors that contributed to the low carbohydrate intake such as the types of foods that were available. The forces of natural selection on the evolutionary processes in humans can have a broad range of effects on the characteristics of humans. There are no concrete answers to some of the questions proposed in this paper, but time will soon tell exactly how the evolutionary mechanisms have effected the human race. The human species will continue to evolve as long as the mechanisms of evolution and environmental factors act upon us.