Charles Darwin’s Theory of Natural Selection

The famous naturalist Charles Darwin presented the theory of natural selection. He went on many journeys on sea and on land, following his interests of the nature and the change that happens in the nature, i.e., the change in species. Following his exposure to many different kinds of birds, insects and animals, he explained Natural Selection as "presentation of favorable variations and the rejecting of injurious variations."(131). Darwin used analogies and metaphors to demonstrate that different alterations occurred in the same specie, which helped them to adapt to their surroundings.

Darwin's theory of natural selection was based on the following facts: 1) organisms increase more rapidly than their food supply. He quotes that there are finite number of resources, therefore making him a Neo-Malthusian. 2) Due to natural selection, there is never overpopulation in animals, because some of them will be eliminated at a young age due to unfavorable environment. 3) Due to limited resources, all life forms struggle to survive, but only the superior ones survive. 4) Those individuals that possess some characteristic that are useful in adapting the environment increase their chances of survival, and produce more offspring with the favorable characteristic and pass them to the next generations. Due to the variations in characteristic and physical changes, the new individual will eventually become so distinct that they will constitute different specie.

Sexual competition is an important aspect that "depends, not on a struggle for existence, but on a struggle between the males for the possession of the females ". It does not affect the death of the recessive individual, but it results in fewer or no offspring for that male. Victory depends on special traits. For example: a hornless stag or spur less cock would not have a good chance of leaving offspring. Darwin provides graphic examples of species warfare by saying "male salmons have been seen fighting all day long; male stag-beetles often bear wounds from the huge mandibles of other males". These weapons and shields of animals are as important for victory as swords or spears, are for humans. Sexual selection also involves attracting females by show or aesthetics; some birds as Guiana display their gorgeous plumage and perform strange antics in front of the females, who choose the most attractive partner for them. Darwin believed that "when the males and females of any animal have the same general habits of life, but differ in structure, color, or ornament, such differences have been mainly caused by sexual selection".