Evolution
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The definition of evolution is change over time. It has been agreed upon by the vast majority of the world that evolution happens and species are not immutable, unchanged. Theories have been experimented with, but the one accepted by scientists is Darwin’s theory of natural selection.
Darwin’s trip aboard the Beagle brought about one of the most important scientific realizations of all time. He realized that on the Galapagos Islands there were different types of finches. The finches looked very similar to the finches found back on the mainland. The difference between the finches from island to island was the size of their beaks. Each island’s finches seemed to have a beak fit for a particular kind of food. Darwin found 9 species of finch.
The question is this: Why would there be 9 different types of finches for three islands that are so similar? The answer Darwin believed was natural selection. Natural selection occurs in a series of six steps. Natural selection is based on the idea of competing to be the one who gets to reproduce and pass on its genes that somehow made it more fit to survive and compete than the one who did not get to reproduce.
Natural selection will only take place if there is a competition for resources. Overpopulation occurs because a species is able to reproduce without worrying about food or predators. Since there is nothing to control the population there is now a competition for the available resources. The animals better equipped to compete for the resources or are able to keep form being eaten win the struggle for existence. From this struggle for existence variety springs up. The animals of a species may look the same but they are not. Some are faster or slower, stronger or weaker, more resistant to disease, or may be better at obtaining food.
The competition that is occurring forces selection to happen. Some members of the species will survive while others will die off. The ones better equipped to handle the world get to reproduce. Those traits that helped those certain members of the species survive will now get passed on to the next generation.
After generations and generations of developing these new traits, new species can arise. Certain traits will get passed along in one line, but a different trait will get passed along in a different line. When these two lines get so different that they either cannot or will not mate, that is when new species have formed.
It is important to realize that evolution does not happen to an individual. Evolution occurs in a population. A certain number of individuals in a population have a trait that is “better” than the other members of the population’s traits. These individuals pass this trait on to the next generation, and in the next generation there might be a mutation in a certain gene that makes this generation even better than the previous one. This goes on for millions of years and eventually we end up with the diversity we see on earth today.
Natural selection can be shown in a simplistic way using the “Jelly Bean Theory”. Jelly Beans are able to survive, not get eaten, by “developing” undesirable traits from our point of view. From natures point of view these traits are actually desirable because they allow the jelly beans to not get eaten. The reds and the pinks tasted the best to us, so those jelly beans went extinct the quickest. Black was the worst tasting one, so it one the competition to not get eaten and was able to reproduce more than any of the other jelly beans. Nature selected black to survive because it tasted the worst to its predators.
We can also see how natural selection works by comparing it to artificial selection. Artificial selection is when humans are choosing the desirable traits not nature. When breeding dogs humans find one particular trait that’s desirable. We find two dogs that express this trait and breed those two dogs together. They have a litter of puppies and again we find dogs in that litter that have the desirable trait and breed them. On and on this goes until we see that different kinds of dogs have different features belonging only to them. Hounds have long snouts because they are bred for hunting. Huskies are big and muscular because they are bread for pulling heavy objects.
Dogs all seem to be very different in appearance,