origin of species

Topics: Charles Darwin, Natural selection, Evolution Pages: 6 (2253 words) Published: December 8, 2013


Origin of species; Critical Evaluation of Darwinian Theory
Cristina Nava
North Salinas High School
Instructor: Mr. Zelensky

Charles Darwin implied in his book, On the Origin of Species (1859), a theory for evolution and its mechanisms. In his book Darwin intends to convey the reader that descent with modification and natural selection, part of the evolution theory, has occurred. He also writes about the “problem of purpose” idea and how evolution and natural selection solve that problem. Many who have been exposed to Darwin’s ideas have argued that natural selection transformed the art of natural history into the science of biology. After reading the first four chapters of his book it is concluded that natural selection is a very important part of Darwin’s theory of evolution. Charles Darwin author of, On the Origin of Species (1859), clearly states that natural selection and descent with modification have occurred. Descent with modification as well as natural selection plays an important role in evolution. Through Darwin’s first four chapters he gives various examples. He explains effects of Habitat and of the use or disuse of parts. An example he uses for that principle is domesticated animals. For example he uses the domesticated duck, where the bones of the wings weigh less than the bones of the legs; and the cows and goats that are milked often they use those organs whereas in other countries they might not (Darwin C., 1859). He also enforces the domestic pigeon as an example and takes time to actually explain it thoroughly. It was also very difficult for Darwin to believe that all the different breeds of pigeons developed from a common ancestor. Despite that he was able to prove that, by the research he gathered. There are many different breeds of pigeons just as there are of other domesticated animals. In the breeds of pigeons there is a great variety of bone structures that these pigeons have developed. Some differences in the bone structure are the face length as well as the jaw

length, also the vertebrate and the number of ribs they have. His evidence are from observations he kept of almost any breed of pigeon there is, and of some experiments he conducted himself of crossing different types of pigeon breeds to see the outcome. Adaptation is also another example Darwin uses, he explains how horses have adapted to live on either cultivated land or mountain pasture (Darwin C., 1859). This is not only applied to the horse but also for cattle, sheep, and any other species that have been able to adapt so it will be able to pass down the selected traits to its offspring. Unconscious selection is just as important as natural selection. Both of these selections select for desirable traits and characteristics. Unconscious selection is when we as humans, breed animals to get certain characteristics to produce the best individual species. Natural selection selects characteristics that are best fitted to survive in that environment. For example the Galapagos birds, the birds that survived in the certain islands adapted and were selected to be able to feed off the available food. For unconscious selection we as humans do it all the time. We want everything better. We select for the biggest animals, because they provide the most meat. Fruit and vegetables have also been altered by us, bigger to have more of certain vitamins and minerals. We pick out the best seedlings, and keep doing that, yet we are never satisfied, we always want more and better. Individual differences are also big parts that serve as an example. These differences can have either been inherited or been caused by mutations. It is a big part because it helps determine the next generation’s characteristics and traits. An individual difference is the separation between sexes. Males and females are definitely very distinct. In fact sometimes as said earlier, there is unconscious selection between the two...
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