Darwin's Theory Of Natural Selection And Evolution example essay topic

Charles Darwin in his book, On the Origin of Species, presents us with a theory of natural selection. This theory is his attempt at an explanation on how the world and its species came to be the way that we know them now. Darwin writes on how through a process of millions of years, through the effects of man and the effects of nature, species have had a trial and error experiment ongoing. It is through these trials that the natural world has developed beneficial anomalies that at times seem too great to be the work of chance. Darwin writes on how a species will adapt to its surrounding given enough time. When an animal gains a genetic edge over its competitors, be they of the same species or of another genus altogether, the animal has increased its chance of either procreation or adaptation.

When this animal has this beneficial variance, the advantage becomes his and because of this, the trait is then passed on to the animals offspring. The theory of natural selection is not limited to inheritable and beneficial variations of a species. It also relies a great deal on the population growth and death of a species. For a species to continue to exist it must make sure of a few things. It must first produce more offspring than survive. If this is not done then the species is obviously going to die off.

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. It is the unchanged species that are in immediate conflict with the species undergoing the natural adaptation that stand to suffer the greatest.

Darwin's theory has shed a potential light on many issues involving the natural world. However there are many arguments about his thoughts. Many people do not take the theory of evolution as their choice of doctrines. Instead they believe in Creationism or a hybrid of the two in which God assisted evolution.

To these people, Darwin's theory of Natural selection and evolution is full of holes. One of the strongest arguments presented to evolutionists pertains to the formation of organs of extreme perfection and complication. In On the Origin of Species, Darwin pays particular attention to this question and gives the problem its deserving time. For the purpose of defending his theories, he sites the eye as the organ of extreme perfection. It is true that the eye is a fabulous tool. A light sensitive optic nerve sits at the back of a mechanism that man was incapable of duplicating until the early nineteenth century.

A complex series of lenses bend light in such a way that it is focused onto the optic nerve, which can then, in turn, read the light and produce an image in the brain. This is a neat trick, and unfortunately for Darwin a complicated question. To look at the origin of any organ of extreme perfection Darwin found it necessary to trace the lineage of the animal (the one housing the organ) back to its formative ancestors. This is, unfortunately, quite difficult and improbable of success. Therefore the only approach to take in this case is to look at a different species that came from the same parent form, or as Darwin puts it, "collateral descendants". This is not possible, however, with reference to vertebrates for even the farthest of our collateral brothers have fully functional eyes.

Instead Darwin delved into the realm of the Articulata. In the Articulata Darwin found an optic nerve covered with pigment and little more. This nerve is merely a light sensing freckle and can be traced through a series of branching and improvements until we can see it approach perfection. As Darwin states on page 188; .".. bearing in mind how small the number of living animals is in proportion to those that have become extinct, I can see no very great difficulty... in believing that natural selection has converted the simple apparatus of the optic nerve merely coated with pigment and invested by transparent membrane, into an optical instrument as perfect as is possessed by any member of the great Articulate class". After millions of years of evolution and natural selection, why is it not possible that a thing as perfect as the eye has been developed. It is hard, however, to believe in this whole-heartedly.

The more I read of Darwin, the more I begin to see the holes in the theory. My belief does not swing towards the thought of creationism. To me that is not an option. However, Darwin has done a great job of stating the arguments and as best a job answering them as he could. It is very difficult to respond to difficult questions with nothing but theory to back them up. He has, nonetheless, defended them to the best of his abilities and his responses are, with a little faith in science, more than acceptable.

Yet another quibbling point brought to attention by Chuck is the existence of neuter insects. The question being that if natural selection only works through a process of slight variation, and only the beneficial variants remain, then why are there neuter insects? Why would nature have seen it fit to not only create these unfortunate slaves but to find them important enough to keep? Darwin attacks this question a little more effectively, I feel, than he did in the latter segment. His argument in this case seems stronger, perhaps because he has more scientific evidence than he had at his disposal on other topics.

Darwin uses the example of the neuter worker ants. His reasoning for the neuter gender, on the surface, is much the same as the reasoning for all of the arguments presented to him. He says that he can find neuter insects explicable if. ".. such insects had been social, and it had been profitable to the community that a number should have been annually born capable of work, but incapable of procreation [He] can see no very great difficulty in this being affected by natural selection". (p. 236) This is not the end for this argument though. Darwin then puts forth the question, that if a creature is neuter, how does it pass along to its progeny the variations it has acquired. The easy and correct answer is that it doesn't. Then how can this be answered by natural selection?

Moreover, how can the neuter variant have been passed along and slowly adapted over the ages? It is in defense of this line of questioning that Darwin truly shines. He states that the selection not only involves the individual but the family as a whole. A parent does not pass its genetic information and its beneficial variance to only one of its progeny; it passes it to all of them.

There fore if it is beneficial to the community of ants to pass along the variation of producing sterile creatures than there is no reason that it should not be. And in this encoding for the sterile creatures more variation begins to exist than we can begin to see how sterile females and fertile females can gradually, over the years, become further and further apart from one another. To drive this point home, Darwin points out that in the same nest of ants he found. ".. two bodies of sterile workers in the same nest, differing not only in size, but in their organs of vision, yet connected by some few members in an intermediate condition". (p. 240) To then tie the whole thing together, Darwin defends the concept of an ant being sterile being beneficial to the community. Since the worker ant is not a trained animal and since the worker ant has no manufactured tools, it must therefore rely on instinct.

If this ant had been fertile and had this ant been along to intermingle with the rest of the community then the natural instincts used by the worker would be lost in the interbreeding. Therefore it is most beneficial to have worker ants be neuter. Darwin has in my mind wholly and completely defended this point. He has combined his theory with an inescapable scientific fact. If a person releases a balloon it will float wherever the wind will take it. But if that same person were to tie it to a rock then that balloon is going nowhere.

That is what Darwin has very effectively done in this section. He has taken his theory and tied it to fact. The last and what I feel to be the strongest argument I am going to talk about is the classic "missing link" argument. Why is it that the world's plants and animals have been changing ever-so-slightly over the last million years, yet we can find only what we believe to be the beginning and the end?

Where, throughout these millions of years of change and variance, did the bodies of the intermediaries go? This is the strongest argument for the creationist viewpoint. I say this for two reasons: one, it's a very good question, and two, no one in Darwin's day and no one in ours has a good answer. Where, indeed, did the bodies go? Darwin, on page 173 states that the best answer he can come up with is that the fossilized remains of our lineage is somewhere under the sea. .".. their remains being imbedded and preserved to a future age only in masses of sediment sufficiently thick and extensive to withstand an enormous amount of future degradation... Whilst the bed of the sea is stationary or is rising, or when very little sediment is being deposited, there will be blanks in our geological history".

This is why I think this is the most profound argument that the creationists have. When the best argument Darwin can come up with, while scientifically feasible, is a little flat. Darwin's secondary response to this query is a little better than the first because it at least plays on his theory and ties it back together. His response states that the theory of natural selection proposes that variation is a long drawn out process. If a person were to find the remains of an animal from thousands of years ago, there would be little or no difference between it and its present day cousins. Therefore, the only reason we have not yet found an intermediary is that we have not yet dug deep enough.

Throughout his treatise, Darwin has presented his theory, presented the arguments, and defended himself against those arguments. In most of the cases, I feel he has done a sufficient job at defending his word. In the majority of cases he had scientific proof and a viable answer to back him up. But of course I could not say in good faith that he was one hundred percent. Sometimes his arguments fell a little flat and at other times he sounded a bit trite as if he were challenging others to come up with a better answer. And in some ways I hope he was.

In the meantime, however, I think he could have done a better job. I am an evolutionist. I have always been an evolutionist. And I cannot foresee anything short of the hand of god changing my mind (which would be a whole other can of worms considering I am an atheist). For years now I have known the premise of Darwin's theory of natural selection. And for years now I have blindly believed it.

Having read his book, I can still say that I believe in evolution, and I believe in Darwin's work. But if there was ever a doubt in my mind it was only because Darwin put it there. It is because of this that I truly think Darwin was fair in the utmost sense of the word. Had he not been fair, which he could have been, he could have made a most convincing argument.

But he stated every question in his theories and did his best to rebut. And I feel that in his rebuttal, he was convincing indeed.