On the Origin of Species presented Darwin's contemporaries with two major proposals. The first proposal was that of "decent with modification", which says that all life originated from a common ancestor by divergence among lineages of species. The second proposal was that natural selection is the main, but not exclusive, mechanism for this divergence of lineages. Proof for Darwin's first argument of "decent with modification" came from his analysis in patterns of morphology, embryology, geography, and fossil records. It was a systematic method of comparing organisms with their ancestors in order to look for similarities along lineages. Finding proof for natural selection, the mechanism by which evolution occurs, was a far greater challenge for Darwin. Without adequate time and field study, it was almost impossible to see natural selection in action. To this day, "few studies have persisted long enough for us to be able to generalize about the temporal pattern and predictability of basic evolutionary processes in unconstrained natural populations" (Grant et.
al, 2002). I will show that Darwin adequately gives support for natural selection by presenting the reader with information in a very sequential manner, and this allows him to draw analogy between natural selection and selection by man (artificial selection). I will then discuss papers to determine if they are consistent with Darwin's hypothesis of natural selection.
In The Origin of Species, Darwin begins his argument by analyzing variations within groups of domestic animals. His primary example of this is the vast differences in varieties of domestic pigeons, all of which he argues were developed from the rock pigeon. From the wild rock pigeon, he claims, breeders had produced a huge variety of different pigeon breeds by selecting individuals with traits they found appealing. Darwin gives many other examples of this variation, which includes dogs, flowering plants,