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,...