The book begins with countless illustrations, which Darwin sketched while on tour of the world. These illustrations are periodically mentioned throughout the piece as evidence to support his theory. After the sketches, the book is divided into chapters of varying intentions. The first few chapters give brief examples and a history of the theory of evolution. His theory is not directly stated until chapter four. After this chapter, the rest of the book is comprised of subsequent chapters that give examples to prove his theory, but more importantly, he outlines all possible flaws in his theory and concisely proves their inaccuracy.
In the first chapter, “Variation under domestication”, Darwin begins setting the framework for his later theory. His main topic in this chapter is ability of humans to create variations in a species for a desired trait, such as sweetness of a fruit or the beauty of a pigeon. Everyone at that time knew that choice breeding for desired modifications were possible, but what Darwin showed was that if humans are able to change a species ever so slightly throughout such a short period of time, the possibilities of nature achieving this over millions of years is not only plausible, but inevitable. One of the other major realizations came while he was studying pigeons; Darwin, with the help of other naturalists, was able to deduce that all the different breeds of pigeons could trace their lineage back to the common rock-pigeon, at least within the confines of the United Kingdom. What this helped Darwin notice is that if all the different species on Earth were created, and they never went through the process of evolution, what was the purpose of so many different types of one bird? The pigeon alone had eight different breeds within a small radius. Surely, he believed, there must be an explanation for why there are so many animals on this planet that display common traits, and yet virtually everything about them is different.
Chapter two and three are also used as a preface to his theory, but they are not as critical and due to the limited amount of space, I will refrain from divulging in to too much detail. The main points that are covered in these sections include all the variants found in nature, the similarities between animals thousands of miles apart, and the struggle for a species to survive due to all sorts of diseases and the multitudes of competitions for the necessities of life in nature.
Finally, in chapter four, we reach “Natural Selection”. Of all the sections in the book, this is the most important. These forty-three pages of brilliance outline perfectly how everything in nature is molded by this fundamental property that has been occurring for millions of years. The main ideas presented include sexual selection, extinction, functions of evolution.
Due to the competition for resources among all species on Earth, Darwin realized that there is a limit to all population expansion; a metaphorical roof is placed...