Darwin’s Theory of Evolution and Natural Selection

“In the struggle for survival, the fittest win out at the expense of their rivals because they succeed in adapting themselves best to their environment.”

Charles Darwin

The theory of evolution, according to Darwin, was based on the theory that species that are “fit” survive better in a changing environment, a statement which he coined “survival for the fittest.” The term fit in this statement insinuates that the type of organism is the microorganism or population which are better adapted to the environment both physically and genetically. This would enable easier adaptation to the particular species that, on the contrary, would be detrimental to other non-adopted ones. This has been shown by the evidence of certain features, either physical or genetic.

An example of this type of survival for the fittest theory would be the peppered moths (Biston betularia) of England in the 19th century. There are two types of moths: the dark-colored ones called the “carbonaria” and the dark form referred to as the typical. In the early years of the century, the moths were typical, light in color, and the barks of the trees were covered with lichen, thereby making them lighter in color. However, during the rapid period of industrialization in England between the half and the end of the 1800s, the darker type was the predominant type.

This is because pollution from the industrial emissions caused led to the destruction and death of the lichens that were light in color, thereby making the barks to be darker. This meant that the carbonaria form survived more because they were “fit” for that environment. The principle behind this is that the birds, which were the primary predators of these moths, fed on the easily seen moths. Therefore, the typical form survived in the early years because they were camouflaged in the light barks. However, this was reversed after industrialization, where the carbonaria form was hidden in the dark barks of the trees.