Darwin- The Origin of Species

Lastly, Darwin discusses the mechanism of natural selection for which evolution can ultimately occur. Using the example given in Origin about natural selection, say when a giraffe is born with a longer neck than its herd, it gains an advantage because it is able to reach more food. The reason Darwin believed in such a radical notion was by continuously observing the anatomy of different species of animals. In Origin, Darwin covers the imperfections of the geological record by focusing on the distance of the continents. The whale's flipper has "finger" bones, with tiny, almost non-existent wrist bones that lead to what would be the humerus bone in the human skeleton and so on throughout the skeleton. It was found that each species require a certain niche in nature; they need their own food, water, territory and sometimes these niches overlap with the niches of another species which creates competition for survival. He observes that on different continents, along the coasts, there are coinciding fossils of the same basic species, however different sub-divisions. The offspring are born with the same long neck as their parents, though some might have even longer necks and thus the short-neck giraffes will ultimately die out. It was invaluable to read and I enjoyed it thoroughly. I forget that it was only published in 1859, so genetics had not even been a field of study at that time. Although Darwin did not know himself the reason behind heredity of certain traits, he strongly believed in the mechanism of natural selection as a process of evolution. The long-neck giraffe is therefore stronger, lives longer, and more likely to have offspring.

Another issue Darwin discusses in Origin is his idea that all species on earth descended from only a few common ancestors. Part of this concept was the idea called population speciation.