I learned about Darwin’s theory of evolution a couple years ago in a biology class. According to Darwin’s theory, all forms of life have been constantly evolving over millions of years. When Darwin came out with his theory, people did not want to believe him since his theory challenged the bible’s version of the origin of the world. Darwin spent his life doing research on different animal species. When he went on a trip to several tropical islands he found different types of finches on each island with each type being specifically adapted to the environmental condition on the island they were living on. He found that all members of a certain species were perfectly adapted to their habitat. A case of Darwin’s theory in play that my biology teacher cited was about a species of moths that was living on birches. The moths’ wings were colored so that they would blend in with the trees. When the moths’ habitat was turned into an industrial area, there could be found an increasing number of dark colored moths. The darker colored moths blended in perfectly with the birches that were colored dark from the smoke of the factories while the whiter colored moths would stand out on the dark trees. The moth species had evolved over time, and it had adapted to the change in their habitat. Only darker colored moths not easily made out by their enemies on the darker trees were the ones who would escape being eaten and get the chance to reproduce and pass their traits on to their offspring. This is a perfect example of Darwin’s theory of natural selection. According to Darwin, nature has a selection process that makes it possible for species to survive in an ever changing world.
When I read Darwin’s essay on Understanding Natural Selection, I was surprised how much I had retained from my biology class. Of course, Darwin has many more examples to offer, and he uses vivid language for the explanation of his theory. He writes in his essay that natural selection is happening every day all over the world. All types of living things have processes of naturally eliminating what does not work for their species and carrying on beneficial traits to their offspring, so that the species as a whole is constantly being improved. This leads to an ever changing world. According to Darwin, one way natural selection might be exhibited is when a species of birds displays a certain coloration of its plumage that blends in with their habitat so that a hawk will have difficulties detecting the birds. Once a certain kind of color has proven to protect the species from their enemies, it will show up in its offspring with consistency until a change in their habitat makes a change of their plumage color a necessity for the survival of the species. Darwin explains in his essay that any modification of a species will always be of beneficial nature or the modification would not take place since a disadvantageous alteration would lead to the extinction of the species. Furthermore, Darwin uses a pack of wolves as an example to illustrate his theory of natural selection. He says that any beneficial alteration in a wolf’s personality or structure has a good chance of being passed on to its offspring. The wolf’s young will then pass the alteration on to their children. Over generations of wolves, a new variety will form. For example, a species of wolves that is best suited to hunt in the lowlands and another species of wolves that is best fitted for hunting in mountainous terrain might evolve.
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Mizuki said,
July 12, 2009 @ 2:37 am
I also took a biology class recently and learned Darwin’s theory was one of the major theories in an ecosystem. Your examples about the colors of moths are easy and inteligible. I agree with you that mimicry and behaviors of camoflage are good examples of living things’ modification for survival. Indeed, the world is ever changing and no moment is wasted.