It is also important for the species to propagate at such a rate as to allow for variance, for it is variance that will ultimately allow the animal to exist comfortably in his surroundings. In his studies, Darwin was led to understand that “…the species of the larger genera in each country would oftener present varieties, than the species of the smaller genera;” (p. 55). Thus the larger species would adapt while the smaller one would not. And to quote Darwin again, “…if any one species does not become modified and improved in a corresponding degree with its competitors, it will soon be exterminated.” (p. 102) Extinction, although not as pleasant a concept as the idea of adapting to ones surroundings, plays just as large a role in natural selection as anything else. As one adaptation of a species proves beneficial, and as that variation begins to propagate, the original, less advantageous variant will die off.
Darwin challenged the traditional ways of thinking by presenting his theory of biological evolution. Prior to the discoveries of Darwin, it was believed that every creature on earth was divinely and created specifically by God. Darwin’s theory presented that all life started from a single species. Part of this species would then randomly develop characteristics that were not found in some of the other members, and the adaptations would enable the species to survive or hinder it from surviving. Over time these changes would result in many completely different species that struggled for survival.
Although this sounds a lot like Darwin’s theory, it is quite different as Darwin did not believe in active adaptation but he did believe in random mutations and selection. He believed that the species develop at random but whichever species becomes most adapted to its environment will then survive and take over the entire population. However, Lamarck believed that an organism will keep on developing until it is finally most suited to its environment/surroundings. He thought that when an animal uses an organ extensively it becomes stronger and then will be stronger in its offspring. Lamarck believed that certain animals stretched their body parts to adapt to their surroundings.
Containing and carrying over traits from a previous environment that are advantages in ones new environment is known as pre-adaptation. During the selective process, traits get passed down to future generations. An interesting thing about traits is that they do not evolve because organisms need them to evolve or to help them adapt to their environment. Traits evolve simply because of chance. For instance, according to early human swapped bite for brain, there was a trait mutation that weakened the humans jaw muscles.
Genetic drift is where there is a change in the genetic makeup of the next generation due to a change in the allele frequency in the next generation. This occurs all by chance alone, and may have its greatest impact on smaller populations than larger ones. The change in allele may or may not be for the better. When the sequence of a gene is modified due to a mistake it is a mutation. If the mutation is advantageous to a species, such no longer being susceptible to a pesticide, increases gene variation for future generations.
Darwin understood that organisms are variable, but for a long time he lacked a mechanism, or a driving force, of evolution. Natural selection, or a complex natural process of elimination, turned out to be one of Darwin’s most ingenious contributions to evolutionary thought (Mayr, 2001). Natural selection is the process by which genetic variation is sorted through and selected for through the organism’s ability to survive. Selection may be due to environmental conditions, competition with other species, or reproductive success. Those organisms that survive can then go on to reproduce, and their offspring then carry the successful traits.
The causes of genetic diseases and disabilities in older individuals are explained by three evolutionary theories: antagonistic pleiotropy theory, mutation accumulation theory and disposable soma theory. These theories suggest that favorable natural selection and heavy allocation of resources for somatic maintenance during the reproductive period decreases the chances of genetic diseases in younger individuals. The antagonist pleiotropy theory was introduced by Charles Williams in 1957. Pleiotropy occurs when one gene affects multiple traits in the body. The antagonistic pleiotropy theory asserts that natural selection favors genes that benefit fitness in early life despite their harmful effects in later life (Gavrilov and Gavrilova 341).
In conclusion, Lamarck’s theory involves adaptations to create new variations, followed by the inheritance of these characteristics, while Darwin’s theory involves random hereditary variation first, followed by the selection of the variation. Genetics has disproven Lamarck’s theory on the basis that characteristics acquired during the lifetime of a parent are not passed onto the offspring. On the other hand, Darwin’s theory failed in explaining why a beneficial change-the loss of functionality of the appendix, for instance- can be passed generation after generation. However, Lamarck and Darwin both believed that life is continuously changing and that organisms change to be better suited to their environment (Mills 2004:119-121).
Shark destruction The film Sharkwater is a documentary directed and produced by Rob Stewart. Rob is an underwater photographer and a biologist that has a fascination with sharks, and their behavioral aspects. His way of studying these creatures he is able to learn about life and how to survive on this earth. This film showed the characteristics of reflexive documentary, this is because of the attention drawn into the sharks, their behaviors, and how we are affecting them. A statement that really stuck the documentary is people are taught their whole entire lives that sharks are dangerous but when you finally see it underwater your whole life can change in a flash.
Charles Darwin is well-known for his groundbreaking work on evolutionary biology. Among his many contributions, The Origin of Species is the most associated with his name. He introduces the scientific theory of evolution and suggests that species have evolved over a period of many generations through a process called natural selection. Darwin's theories have created much controversy among his colleagues and led to great amounts of debate. However, the massive amount of criticism directed at Darwin convinced him to make to revisions.