A Review of Darwin's "The Origin of Species"

Darwin’s The Origin of Species is one of the most important books written during the past 150 years. It provides the foundation for modern biology, but its influence extends far beyond biology to such distant areas as ethics. It has been called “the book that shook the world.” Its impact on man’s concept of himself and the world has been greater than the works of Copernicus or Newton. It has been said that it would be impossible to understand the history of western culture in the last half of the 19th century and the entire 20th century without a discussion of the impact of Darwin’s book.

The Origin of Species has also often been cited as refuting the biblical account of the origins of biological species by providing a naturalistic account of origins. If indeed Darwin’s work does refute certain claims of Scripture, the foundation of Christian faith would be nullified. Therefore, Darwin’s book warrants attention.

In this article I will review the central argument in Darwin’s book, with an eye on the following specific questions:

What is the structure of Darwin’s argument in his much esteemed book?
How adequately does he make his case?
What role should Darwin’s book play in the debate on origins?

THE ARGUMENT

In his introduction to The Origin of Species, Darwin (1859) lays out the core of the theory:

I can entertain no doubt, after the most deliberate study and dispassionate judgment of which I am capable, that the view which most naturalists entertain, and which I formerly entertained—namely, that each species has been independently created—is erroneous. I am fully convinced that species are not immutable; but that those belonging to what are called the same genera are linear descendants of some other and generally extinct species, in the same manner as the acknowledged varieties of any species are the descendents of that species. Furthermore, I am convinced that Natural Selection has been the main but not the exclusive means of modification.

Darwin begins his argument by examining variations within domestic animal groups. Particular traits within a species can be chosen, and man’s ability to push selection in a particular direction can result in large variations within a species. His primary example is the vast differences in varieties of domestic pigeons, all of which Darwin argues were developed from the rock pigeon. It is interesting to realize that Darwin was drawing the opposite conclusion that traditional biology drew when it looked at variations of domestic species. Traditional biologists would point to the large varieties of domestic pigeons as an illustration that extreme selective breeding could only push a species so far. Species had fixed boundaries. Also, if the selective pressure was abandoned, within a couple of generations the pigeons would have returned to “normal.” Darwin was emphasizing only the ability of human selection to accentuate variations within the species.

In the next three chapters, Darwin developed his notion of variation under nature. It paralleled his discussion of domestic variation. Darwin began by claiming that he would not define a species, although he believed that every naturalist knew vaguely what one was (for a listing of the classification scheme, see the chart on page 4). For Darwin, the distinction between species and variations is vague and arbitrary. Species are simply strongly marked and permanent varieties (Darwin, p. 108). Variations occur within species, and some variations have a better chance of surviving than other variations. Natural selection, commonly termed ‘survival of the fittest’, is seen as a mechanism preserving the favorable variations and destroying the injurious variations. Therefore, varieties slowly develop into independent and permanent species. Nature makes no big leaps. Darwin saw this as a physiological division of labor. More specialized species were better “adapted” than earlier species.

In the traditional view, species were considered to be independently created and immutable. As Darwin saw it, species arose from closely related but earlier species. During the past 150 years, biology has confirmed Darwin’s argument. Case after case has been reported of variations of plants and animals that are transformed into species. A famous example is the case of the leopard frog, Rana pipiens, which lives throughout the lower 48 states. If we divide the U.S. into nine zones from west to east, and label them zones A through I, we find that when we mate frogs from adjacent zones, for example, A and B, or G and F, they produce fertile offspring. However, if we attempt to mate a frog from zone A to one from zone I, the offspring are not fertile. What we are seeing is differentiation of Rana pipiens into two separate species. A great number of examples of this type have been observed in a wide range of plants and animals. There is little doubt that Darwin is correct in his argument here.

If Darwin would have ended his argument at this point, he would have accomplished all that he set out to do in his introduction. He would have shown that species are not fixed and immutable, rather they result from natural selection of earlier existing varieties and species. However, in later chapters he argued that the same mechanism functions over greater time scales and is the driving force for the development of higher biological groupings such as Classes (Darwin, p. 320, p. 398). Darwin claims his theory is analogous to Lyell’s Uniformitarianism in geology: species slowly develop from variations by natural selection in the same way that the coast waves slowly cut the valleys and cliffs (Darwin, p. 142).

Specifically what Darwin has in mind is a biological analog of Uniformitarianism, which claims that geologic processes operating at modern-day frequencies and magnitudes can account for the landforms we see. All we need is sufficient time. So, when Lyell looks out and sees the waves crashing onto the coastal cliffs of England, he can envision the present shape of the cliffs as a result of thousands of years of waves crashing into the shoreline at their current strength. Analogously, Darwin sees that some variations have a better chance of surviving, and the species we see today are the result of natural selection operating over long periods of time. The belief serving as the foundation of Uniformitarianism is that nature is a continuum; that is, the predominant processes we see at work can be extrapolated over large time and space scales. (The opposite view is that nature is hierarchical: processes that predominate at one space and time scale may not be relevant at other space and time scales). Darwin’s belief that nature is a continuum allows him to see biological classification as arbitrary, and it allows him to extrapolate from the modern-day process of natural selection operating on varieties in the distant past as the origin of current-day species. It is this belief that allowed Darwin to be little concerned over the definition of species. Any biological grouping would work equally well, for they are all arbitrary. He could have called his book “The Origin of Subspecies,” “The Origin of Species,” or “The Origin of Classes.” The same mechanism is working at all levels of biological classification and time scales.

QUESTIONS

If Darwin’s belief that natural selection is operating on the level of varieties and if nature is indeed a continuum, then his argument is sound, and natural selection can account for the development of Classes and Orders. However, Darwin gives us little evidence to justify his acceptance of this belief. The source for his assumption is undoubtedly Lyell’s Uniformitarianism. For Darwin, the view that nature is a continuum is a presupposition; that is, an accepted but unproven belief that is serving as the foundation of his argument.

Is Darwin’s presupposition that nature is a continuum warranted? Returning to Lyell’s example of the waves forming the coastal cliffs, it is easy to envision the waves over time accounting for the development of the cliffs. However, the alternative explanation is that several different processes are involved in forming the coastline and they are working at different time and space scales.

For example, if I send three scientists to the coast and ask them to tell me what the dominant process forming the coastline is, I get three distinct answers. One scientist says it’s plate tectonics; another says it’s wave action and tides; the third says it’s marine plants and animals making a living. How can this happen? The first scientist is looking at the scale of thousands of kilometers over thousands of years, so he sees plate tectonics as the dominant process. The second scientist is looking at the scale of a hundred meters over hundreds of years, while the third is looking at the scale of one meter over one year. The point is that a process that is relevant at one level may not be relevant at another level. According to the hierarchical view, the shape of the coastline cannot be explained by examining the activities of marine plants and animals on the time frame of a year and extrapolating to a million years.

When we reflect on these two views side by side, I believe that the hierarchical view of nature is more reasonable than the continuum view. While the continuum view rightly recognizes the role of wave action in forming the coastline, this view naively believes that the process of wave action can be extrapolated without limits and can account for all the features of the cliff. It seems far more reasonable to see processes working within particular space and time scales. In a like manner, the process of marine plants and animals making a living cannot be extrapolated past a few meters of area and a time frame of a year or so. At each space and time scale, the dominant process must be empirically established. Someone who understood this point very well was Mark Twain (1874):

In the space of 176 years the lower Mississippi has shortened itself 242 miles. That is an average of a trifle over 1.3 miles per year. Therefore, any calm person, who is not blind or idiotic, can see that in the Old Oolitic Silurian Period, just a million years ago next November, the Lower Mississippi River was upward of 1,300,000 miles long, and stuck out over the Gulf of Mexico like a fishing rod. And by the same token any person can see that 742 years from now the lower Mississippi River will be only 1.75 miles long, and Cairo and New Orleans will have joined their streets together, and be plodding comfortably along under a single mayor and a mutual board of aldermen. There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment in fact.

IMPLICATIONS

Rejection of the presupposition that nature is a continuum has several implications for Darwin’s argument. Biological classification is not just arbitrary groupings along a continuum. Instead, discontinuities exist, which are real boundaries between biological groupings. At least some definitions within the hierarchy are not arbitrary. However, within a particular level of the hierarchy, the biological groupings can be random. As mentioned previously, it also does not necessarily follow logically from his proof of the origin of species that the same mechanism is operative for the origin of Classes. At each level of the hierarchy, Darwin needs to establish natural selection as the dominant process forming the groups at higher levels of classification.

While Darwin has shown empirically that species have developed from pre-existing species, when we move to higher levels of classification (different levels of the hierarchy), like Order and Class, problems begin to develop. First, how can you show empirically that processes operating today at the species level are causing changes at the higher levels of classification over very long periods of time? Second, even if you could show empirically that processes operating today could account for the changes in the organisms over long time periods, the problem of actually showing that this process did in fact cause the changes still remains. Third, Darwin acknowledged that there is an absence of transitional forms in the fossil record, especially at higher levels of classification. If his theory was correct, change in nature occurs gradually. There are no jumps. His explanation for why the fossil record has large gaps in higher level groups was that the fossil record was poor. In fact, he claimed that it must be extremely poor (Darwin, p. 341). If we had a more perfect fossil record, Darwin believed that the gaps between the Classes would diminish. This is not to say that Darwin thought that all transitional forms would ever be accounted for. The intermediate forms would have relatively shorter durations than the more permanent species and they probably would be fewer in number over a smaller geographic area.

Darwin has constructed a fallacious argument here. He claimed that the fossil record is very poor. How could he claim to know that? His answer would be that because there are wide gaps between the groups, the record must be incomplete. His reasoning here is viciously circular. He is trying to prove that transitional forms exist between representative forms in the fossil record. At the same time, he is claiming that the fossil record is poor simply because there are gaps. As long as gaps exist, according to Darwin, the record is poor. If no transitional forms existed, then Darwin would forever conclude that the record was poor.

Thus, to look at the empirical evidence for natural selection causing gradual changes in higher levels of classification is a difficult task, one addressed primarily by paleontologists. When we look at the fossil record today and ask if it supports Darwin’s theory, I believe we must conclude that it does not. In 1859, when Darwin wrote his book, he acknowledged that large gaps existed in the fossil record, but he believed that additional work on the fossil record would eventually close the gaps. Such has not been the case. In fact, one popular theory that was recently introduced by Stephen J. Gould and Niles Eldridge, two leading paleontologists, claims that the fossil record suggests that changes occurred quickly in the higher orders and were followed by long periods of relative stability. Their theory, called punctuated equilibrium, is grounded in a view of the fossil record in which gaps are a common feature. They believe that rapid changes took place in small isolated areas with small populations where there was little chance of leaving fossils. Reading the fossil record this way suggests at least that there are discontinuities (gaps) followed by long periods of relative stability. At any rate, clear empirical support for Darwin’s theory seems lacking at this level. Darwin believed a complete fossil record would yield gradual changes over long periods of time with few discontinuities. This has not been the case.

Therefore, it appears that Darwin’s assumption that nature is a continuum was not warranted. It has led to several errors, including the major one: having shown empirically that the origin of species could be explained by modification from pre-existing species or variations, he theorized that this result could be extrapolated to the higher levels of biological classification.

PRESUPPOSITIONS

A discussion of the role of presuppositions in a work of science might seem to be out of place. However, it is critical if we are to reexamine the question of origins. Traditionally, science is characterized as a method that allows the scientist to be detached and objective and therefore to come to a qualitatively more certain kind of knowledge than other disciplines. By carefully following this method, the biases and presuppositions of the individual scientist are set aside, allowing the scientist to become detached and objective. This view pervades much of the scientific community and the culture at large. However, such a view has been severely criticized by philosophers of science since the late 1950s. After Thomas Kuhn’s The Structure of Scientific Revolutions and Michael Polanyi’s Personal Knowledge pointed out the flaws in the traditional view of science, very few philosophers of science could be found who would claim that the scientific method allows scientists to be detached and objective and to operate without presuppositions.

Clearly, Darwin’s book contains assumptions, and we have only examined one of them. If Darwin’s book is a work of science—and I think it is—and if it provides the foundation of modern biology, then the science of modern biology is based on a set of assumptions.

The relationship, then, between science and other endeavors is not the one we usually hear articulated (that science allows us to attain a qualitatively more certain kind of knowledge than other endeavors). Rather, science is like other fields. What characterizes science is its subject matter. It is the pursuit of knowledge of the physical world. Therefore, while science plays a role in our acquisition of knowledge, it is not the pre-eminent means of acquiring knowledge.

THE BIBLICAL ACCOUNT

The popular account of Darwin’s theory is that it has replaced the traditional biblical account that God created the species independently from each other, and that they are immutable. If my judgment of Darwin’s work is correct, Darwin was right to reject this traditional Christian view of the mid-nineteenth century. Darwin clearly showed that species arose from pre-existing varieties. It had been argued that the traditional Christian perspective was derived from the Genesis account. Close examination of the Genesis account reveals that the text claims that God created all the kinds and their variations (Genesis 1:21). In the traditional biblical account, Genesis 1:21 was interpreted to mean that God created all the kinds (species) and all their variations (subspecies). Even if we accept that the biblical text is referring to species when it talks about kinds, it is not clear to me why that would demand that species are fixed, or that they each necessarily have to be independent, direct creations by God.

However, a far greater difficulty with the traditional view is the interpretation that when Genesis refers to a kind it is referring to a species. Why not a Genus, or a Family? For example, God could have created the kind finches, and the finches that differentiated into particular species would constitute the variations. I do not see anything in the text that would necessarily lead to rejecting this interpretation. It seems that those imposing an interpretation on the biblical text that claimed God created each fixed species independently were in error.

CONCLUSIONS

When we approach a question like origins, we are approaching a difficult and complex subject. In all cases, individuals come to this question with certain assumptions. Their understanding of the data will be affected by their assumptions. For example, we saw in Darwin’s first chapter that he began with observations and drew different conclusions from those of other scientists. Darwin brought a different set of assumptions to the data and therefore reached a different conclusion about it. We need to recognize the role of scientific specialists in the debate; they provide key empirical data. However, we must recognize that their assumptions have influenced what they see. What we need are philosophically sophisticated scientists who recognize the role of presuppositions in coming to knowledge about the question of origins. Such scientists are rare; most have been trained in the traditional view of science. They are quick to see assumptions in others, but they are blind to their own assumptions.

For Christians interested in the questions of origins the problem is more difficult. Not only do we have to examine the physical world and ask what it is we see there, but we have to ask the biblical text the same question. We have to recognize that in both cases we are bringing presuppositions that will influence how we interpret what we see. We need to learn to be sensitive to data that does not fit our perspective and to be able to question our own presuppositions, both about the text and the physical world.

I believe that much about the question of origins has still not been answered and that it remains out there to be discovered. Darwin has provided us with a valuable book. As one of the greatest natural history observers of the 19th century, his insights are important. But to dogmatically accept his work as the foundation of modern biology that has largely answered the question of origins is to believe that most of the creative discovery has been finished. It seems to me that there is no empirical evidence that supports Darwin’s belief that natural selection operating over vast lengths of time could account for the fossil record or for the discontinuities at the level of Classes. I believe that a great number of modern biologists who dogmatically accept that portion of Darwin’s account have made an error. It is an error that removes them from wrestling with some of the more exciting avenues of discovery.

Conversely for Christians, a dogmatic acceptance of a particular Genesis account that answers all of the biological questions concerning origins is equally an error. It also stifles interest in pursuing some of the more exciting avenues of discovery in biology. Christians need to recognize that the interpretation of the Genesis account is difficult and biological information can provide valuable insight into the question of origins.

Literature cited: