Origin of Species by Means

¶ … Origin of Species by Means of Natural Selection by Charles Darwin

Providing a book review for Charles Darwin's on the Origin of Species is a daunting task. After all, the scientific community widely accepts the notions of natural selection and evolution, theories which owe much to Darwin's early works. Furthermore, science has advanced by leaps and bounds since Darwin's day. This makes it difficult, if not impossible, for a modern reviewer to understand what type of insight was required for Darwin to observe these species and come to the conclusion that some type of natural selection was at work. The very notion went against the popular theories of his day, and certainly against the strong religious influences of his time. Not that Darwin was the only naturalist to suggest a process akin to evolution, but even others who agreed with his ideas were dismissed by many. Furthermore, these scientific advances can make it appear that there were weaknesses in Darwin's work. For example, modern scientists can analyze the DNA of different animals and come up with the percentage of DNA that is common to two species, which helps them determine, not only whether the animals came from a modern ancestor, but also when the division between two species may have occurred. Using such evidence, modern scientists know that chimpanzees are more genetically similar to humans than any other apes, while the tools that Darwin could have used for observation may have led to a different conclusion. All of these factors, necessarily, color a modern reader's interpretation of Darwin's benchmark book.

To pretend ignorance of Darwin's theories, or even of the theories that his book helped nurture, is impossible. The modern reader, even a reader who rejects the idea of natural selection or evolution, has grown up with constant exposure to the idea of evolution. Therefore, nothing in the book should seem extremely revolutionary. In fact, much of the information may appear redundant. Therefore, this book review is not going to attempt to approach the information in Darwin's book as if it should all be new or groundbreaking. Nor will the book review attempt to review the book in comparison to a modern scientific text. Instead, this book review will attempt to review the book as a historical scientific document, with the knowledge that the author was free from the burdens and knowledge of later scientific discovery.

Summary

The Origin of Species begins with an introduction to the book. In this introduction, Darwin indicates that he does not think that the theories he is explaining cannot be reconciled with religion. It also lays out Darwin's credentials as a scientist, specifically as a naturalist. He also discusses his journey on the H.M.S. Beagle, and how his observations while on that ship led him to begin pondering the idea of natural selection. He acknowledges that he is not the only naturalist of his time to suggest a theory of natural selection, and admits publishing his incomplete work because of concerns his rival would publish before he could.

Next, Darwin moves onto the intentional breeding of species for desired traits, which occurs in animal husbandry and plant breeding. He describes this as artificial selection, in contrast to the natural selection he describes later in the book. He talks about two different types of artificial selection. He refers to abrupt changes as sports or monstrosities. He also discusses small differences, and notes that it was by observing those small differences that he helped come to an understanding about evolution.

After that, Darwin discusses the idea of the species. He states his opinion that the distinction between a species and a variety is arbitrary, because experts frequently disagree about whether an animal is a new species or simply a variety of another species. Darwin points out that, even within a species, the animals differ from one another. To him, that within-species variation was critical to understanding how natural selection works.

After laying the foundation by showing how artificial selection can create differences in a species, and how inter-species variation is critical, not incidental, Darwin then launches into an explanation of how species develop. It is in this chapter that Darwin really explains natural selection. He explains that there is variation within species. Moreover, if a variation is advantageous for survival, that variation will tend to be transmitted to the offspring. He discusses the struggle for survival in plant and animal species, and points out that this struggle can manifest in many different ways, especially in competition between species. In fact, he suggests that competition is the most extreme when it with a member of the same species or a species that fills the same role in the ecosystem.

Darwin goes on to explain how natural selection does not work in isolation. He describes an ecosystem and how all of the organisms in an ecosystem are interdependent. In this way, Darwin describes how species play a particular role in an ecosystem, and how they can adapt to play that role. Darwin then goes on to discuss the specifics of selection. While he believed that natural selection probably worked slowly in nature, especially when compared to intentional breeding, he used the differences between intentionally bred species to support his belief that species could become very divergent through natural selection. Darwin also discussed sexual selection and how the need to attract mates has led to males having more distinguishing physical features than females.

Darwin's explanation of heredity reflected the general lack of knowledge about heredity that existed during his time. Darwin endorsed a theory of heredity in which characteristics acquired during the lifetime of the parent could be transmitted to the offspring. He also seemed to accept the idea of telogony. If both of these were true, they would increase the chances of desired traits being naturally selected. However, Darwin's acknowledgment that he did not know how heredity worked was not fatal to his theory, because, according to Darwin, one could easily observe that heredity did work.

Of course, Darwin was aware that people would not endorse his theory of evolution through natural selection. He believed one problem with natural selection was the general lack of intermediate forms between closely related species. Darwin acknowledged the lack of such intermediate forms, but suggested reasons for their absence. For example, he suggested that competition between animals filling the same environmental niche was intense, so that one would not expect these intermediate forms to have good long-term survival rates. Next, he talked about his belief that there are animals with intermediate forms, but that they may not be seen as closely related to the species in question. Specifically, he suggested that flying squirrels and flying lemurs (Darwin, 180-181) could be an intermediate species between bats and non-flying rodent ancestors.

One of the more interesting notions that Darwin discusses is the idea of infertility among hybrids. He suggested that this infertility was how nature helped keep species distinct. He suggested that whether or not species could create hybrids was something that varied greatly from species to species. Some species could interbreed easily with related species, while other seemingly closely-related species could not interbreed. To Darwin, the idea of the sterile hybrid and some of the difficulties of hybridization reinforced his belief that the line between species and varieties was a fluid one.

The final major challenge to Darwin's theory was that the fossil record seemed to suggest the sudden development of species, without the incremental changes one would expect in a species experiencing natural selection. Darwin acknowledged that this criticism was true, but suggested that it actually meant very little. He pointed out that the fossil record is imperfect for several reasons, one of the principle reasons being that fossilization is rare. Furthermore, Darwin suggested that the migration of a species into a new area would, if one only examined the local fossil record, suggest the sudden development of a new species. Moreover, Darwin opined that as more fossils were discovered, there would be more evidence for intermediate life forms.

Darwin actually devotes an additional chapter to the fossil record. He attempts to explain how the patterns revealed in the fossil record support the idea of natural selection rather than the creation of individual species. First, he felt that the fact that changes occurred at different rates in different species supported the idea of natural selection, because changes in a species would respond to changes in the environment, as well as create changes in the environment. Therefore, some species may change very little, if at all, over time, while other species may change rapidly. He believed that looking at extinct animals could provide a clue about natural selection, because species that had recently become extinct were more similar to living species than those that had died out at an earlier date.

Next, Darwin discusses the idea of geographic diversity. Given that many locations in the world are essentially similar but have dramatically different flora and fauna, Darwin did not believe that differences in species could be explained through environmental differences. 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.

Analysis

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.