Darwin specifies between three types of selection; artificial selection, natural selection, and sexual selection. The domestic selection is when man breeds animals, and through the breeding selects which traits stay or go. An example he gave in the book was that of bred pigeons. He says that the earliest known cases of domestication were about 3000 B.C. He goes on to list several differences that domesticated pigeons have, and says that he believes they all have descended from the rock-pigeon. Darwin says about artificial selection, “we see in them (domesticated races) adaptation, not indeed to the animal’s or plant’s own good, but to man’s use or fancy.” The selection that is occurring here is that of a plant’s or animal’s traits, being chosen by man.

Natural selection is similar to artificial selection, except nature, instead of man, chooses which traits stay or go. The process by which this happens is dependent on many factors, including; largeness of an area, intercrossing of species, isolation, climate, predators, prey, and food available or vegetation.

In class we discussed the example of rabbits. If there were two colors of rabbits, one group white and the other brown, it is likely that if the climate of the area is cold and snowy, the white rabbit has a better chance of survival, because it is harder for a predator of the rabbit to spot a white one in the snow than a brown one. On the other hand, if the climate was warm and the terrain was brown, the brown rabbit would have a better chance of survival. Natural selection is the main driving force behind evolution. Although Darwin himself did not use the word evolution, or the phrase “survival of the fittest,” these were implications of his theory of natural selection.

Sexual selection is the continuance of certain traits that come from the female choosing which male seems the most attractive to her, or which male ends up reproducing. Darwin uses the example of a female bird choosing the male bird that sings the best. The traits of this male will live on, while those of whom were not chosen will eventually die off.

In Malthus’ Essay on the Principle of Population, he says that the human population will double in a certain time period. He then says that in that same time period, the food nature provides will only increase in one unit increments. So in “two centuries and a quarter the population would be to the means of subsistence as 512 to 10.” In other words, the population is reproducing at a larger rate than that of food. The consequences this has is another aspect of natural selection; survival of the fittest. Only those individuals fit enough to survive predators, diseases, and limitations on food will pass on their traits to the next generation. This is also a form of population control.

Darwin’s theory of selection is phylogenic, or it consists of a tree of species. The tree of species starts off with an ancestral species, from which the different varieties of the species evolved. One of the most famous examples he gives of this came to him on his voyage to the Galapagos Islands. It was there that he observed that different species of finches existed on different islands, each suited for its environment. He concluded that they must have evolved from one specie, and that upon dispersing to the different islands, natural selection played a role in their evolution.

One of the questions that natural selection answered was how species and other things get their present form. Whereas in William Paley’s watchmaker argument, things were created in their present form by a creator to serve a purpose, Darwin’s natural selection said that things in have their current form in order to survive in nature. An example used is the eye. Paley says that the eye, like the telescope, must have been created for a single purpose, in its present form; and that purpose is to see. Darwin says that like everything else, the eye too must have changed over a long period of time in order to adapt to its environment, according to each species that is. Darwin says “we cannot suppose that all the breeds were suddenly produced as perfect and as useful as we now see them; indeed in several cases, we know that this has not been their history. The key is man’s power of accumulative selection.” Even though he is talking about artificial selection here, it is an objection against Paley’s idea that everything was created as it presently.