For example, the species on a single continent are more likely to be similar to one another, even if they live in vastly different environmental conditions, than species from two different continents. Darwin drew heavily upon his experience on the Beagle to suggest that ability to engage in migration was an important component of natural selection. Darwin drew upon examples of islands to help explain his ideas, using examples from his time on the Beagle. For example, he theorized that animals develop to fit certain ecological niches, and that animals of different types might fill those niches in different areas.
After discussing how geography has impacted biology, Darwin moves on to a discussion of how species are classified. He acknowledges that the science behind these classifications is imperfect, as it is based on resemblance. He states his belief that animals with similar traits share a common ancestor. In this way, Darwin suggests that classifying animals and plants involves performing a type of genealogical survey. Darwin looks at the similarities between seemingly diverse animals and how the same basic structures are slightly modified in different animals to result in very different products. "It is, no doubt, extremely difficult even to conjecture by what gradations many structures have been perfected" (Darwin, p.404). In fact, he talks about rudimentary organs, which he calls vestigial organs, which no longer serve a function in an animal species, but which he believes exist because of the animal's evolutionary history.
Darwin concludes his book with a discussion of the possible implications of natural selection. He discusses how interesting it is for one to contemplate the ideas behind evolution. He even acknowledges that he is aware that a theory of natural selection has special implications for the development of human kind. He does not, however, specifically discuss the evolution of man. He specifically does not put forth any theories suggesting that man evolved from monkeys, which is a common misconception people have about Darwin's work.
A modern day reading of Darwin's work makes it appear that the man was not only a gifted naturalist, but also somehow prescient. So many of his theories about natural selection have been substantiated through additional scientific research, that it is difficult to find fault with those theories. For example, Darwin believed that, with future discovery, the fossil record would support the idea of natural selection. The reality is that the fossil record has supported the idea of natural selection, not only in lower plants and animals, but also in humans.
In fact, so many of Darwin's ideas seemed familiar and commonplace, that it was difficult to read the book from a fresh perspective. While the theories, themselves, were familiar, the logic used to reach the theories was not familiar. It is one thing to grow up in a world where evolution is an accepted scientific theory and see similarities in animals that one knows are genetically similar. It is an entirely different notion to be traveling on a ship, noticing similarities between animals, and come to the conclusion that these animals were the product of evolution. Reading the logic in the book made it clear that, while Darwin may have had contemporaries who were contemplating the same information, as a group, these naturalists were groundbreaking scientists. Much of that is lost on the modern person, but becomes clear when one reads how he came to these conclusions.
However, there are places where, because of what modern science can do, Darwin seems very ill-informed. For example, he devotes a significant part of his text to determining what makes a species and how species can be differentiated from subgroups of the same species. So much of his evidence is linked on observable phenomenon, so that animals that look more similar are considered to be more similar. In the day and age of genetic testing, this type of classification scheme seems ridiculous. Today, if a scientist wants to know if two animals are members of the same species, he or she can run genetic sequencing tests that will reveal that answer. In fact, several times in recent history animals that were believed to be parts of different species were revealed to be part of the same species. When one considers the historical context of the text, this anomaly, of course, makes sense. However, when one looks at how valid the text is scientifically, it does mar the text's utility.
There is no doubt that Charles Darwin's on the Origin of Species was a major ground-breaking work. Though other naturalists had been suggesting that some type of evolutionary process helped create modern species, Darwin was the first to put it in a manner that could be easily accessed by the non-scientific reader. In fact, Darwin's work may have been almost too successful. Almost immediately after publication, Darwin began receiving criticism that his work was anti-religious. Though he tried to address those concerns in later editions of his book, the fact was that Darwin's theory did undermine the idea of a creator God that created species in a single creative incident. However, that does not mean that scientists and religious persons have been unable to reconcile the concept of evolution with the idea of God. It simply created a challenge. Because Darwin's work had such a huge sociological impact, it can literally be said to have helped change the fabric of society.
Of course, Darwin's real impact has come in how his text has viewed how scientists have approached the notion of natural selection. Building upon his work, scientists in several fields have established evolution as the primary theory for describing how current species have come into being. Moreover, though it has been fiercely contested at times, scientists have built upon Darwin's original work to establish natural selection as the means by which humans came into being. The idea that humans have, not only evolved, but are in a continual process of evolving has helped shaped understanding of medical and other scientific issues.
Darwin, Charles. The Origin of Species by Means of Natural Selection or the Preservation of Favoured Races in the Struggle for Life. London. Odhams Press Limited,…