English naturalist Charles Darwin (1809–1882) laid the foundations of evolutionary biology through the process of natural selection, which he outlined in his seminal work, On the Origin of Species.
Professor Emeritus of the history of science at Queen’s University in Belfast, Peter J. Bowler authored numerous works on the history of the evolution theory and environmental sciences.
Simply Charly: You’ve been writing about Charles Darwin and the development of Darwinism for many years, and you were the President of the British Society for the History of Science between 2004 and 2006. Could you explain what the term “Darwinism” really refers to? What is the difference between Darwinism and evolutionism?
Peter J. Bowler: It’s easier to begin with “evolutionism,” which refers to any theory that explains the origin of the animals and plant species we see around us in terms of a natural process by which previous forms (some of which have left their remains in the fossil record) changed into the modern ones. Conventionally it’s assumed that the process operated continuously throughout the history of life on earth so that we are all ultimately derived from the first living things. How those first forms of life arose is a different problem, and one we haven’t solved yet.
“Darwinism” is a particular explanation of how the process of evolution occurred. In its most basic form, it proposes a mechanism of change called natural selection, but more broadly, it focuses attention on how species adapt to changes in their environment and rejects any suggestion that there are built-in trends forcing evolution in particular directions, e.g., a progressive trend. For Darwinists, progress is always a by-product of adaptation, and most adaptive changes are not progressive in any meaningful sense—some are even degenerative, as in the evolution of parasites.
Natural selection looks to the variation among the individuals within a population as its raw material (now known to be the result of genetic mutation). The variations are produced without reference to how the species lives, but if by chance one variant/mutation is better adapted to the environment, it will breed more successfully while any that is maladaptive will be weeded out. Over many generations, this will change the genetic makeup of the species to make it better adapted overall. But that’s only “better” in that one environment—if the conditions change, the species will change again.
SC: The bulk of your research and publication addresses not only Darwin but also the history of early 20th-century environmental science as a whole. What first drew you to this field? Why do you believe this is an important subject to study, and what can we learn from examining the development of science in this period?
PJB: I have to confess that I wrote my big book on the environmental sciences only because I was offered a generous advance by the publisher to contribute to the series they were planning to introduce general readers to the history of science. It took me way beyond the areas I normally work in, so I learned to think more widely about how different areas of science link together. I also got to work with the editor of the series, the late Roy Porter, who taught me a lot about writing at this level. Since then, my interests have moved off in different directions, including the study of science and religion, so I haven’t really been keeping up with detailed work in the history of ecology. But I do still think it’s vital for us to think more carefully about the environment and how we study and exploit it. Most people think ecology is something to do with back-to-nature environmentalism, but in fact, it’s a collection of scientific disciplines that study the environment. They have no necessary connection to any ideological position, although of course, they are used by the environmentalists and by their opponents. Looking at history helps us to sort these relationships out by showing how they emerged.
SC: You note in the introduction to Charles Darwin: The Man and his Influence that Darwin was not the only person who had views on evolution in the early 19th century, and neither was his theory of evolution the only one present at the time. Could you briefly summarize who some of the other leading evolutionists were? How did their contributions impact the development of evolutionary theory?
PJB: Charles Darwin certainly wasn’t the first evolutionist, although he played a major role in getting the idea generally accepted and proposed the mechanism (natural selection) that modern biologists have adopted. Around 1800, there were two important figures who promoted the general idea of evolution—the French naturalist J. B. Lamarck and Darwin’s own grandfather, Erasmus Darwin. They thought the process worked by adding up the effects of the individual animals’ efforts to cope with the environment, the so-called “acquired characters” (for example, the blacksmith’s bulging muscles). This process became known as Lamarckism and formed one of the main alternatives to natural selection later on (even Charles Darwin accepted it as a subsidiary mechanism). Only in the early 20th century did the emergence of genetics show that acquired characters cannot be inherited.
SC: Evolution and Darwinism are primarily considered matters of biology, but you note in your History of an Idea that other scientific fields had an impact as well. How did new developments in geology and paleontology support Darwin’s theory of evolution?
PJB: You can’t have a theory of evolution unless you think the earth is immensely old, so in that sense, the emergence of geology as a science was a vital prerequisite. Darwin was also strongly influenced by the geologist Charles Lyell, who insisted that all changes on the earth’s surface are slow and gradual, not catastrophic. Lyell was interested in how animals and plants migrate around the earth as conditions change. That was how Darwin came to study biogeography, most obviously in the Galapagos Islands, as a clue to how evolution works. He saw how representatives of a single species such as the finches had diversified into several different forms once they had been transported to the separate islands in the group.
Fossils were also important in showing that living forms had changed in the course of the earth’s history. But they weren’t really crucial for Darwin because he realized that most species have not left fossil remains, so the few that have been found don’t always offer us a detailed picture of how the evolution of a particular group has occurred. Biogeography was much more important for him.
SC: Darwin was and remains a controversial figure, with (primarily American) fundamentalist groups today still resisting the theory of evolution. You state early in The Man and his Influence that “the resulting debates reveal that even today most ordinary people still do not understand the basic principles upon which Darwin’s theory is based. What do you believe can be done to foster understanding of Darwin’s work and evolutionism as a whole? Is the creationism vs. evolution debate a healthy one, or is it distracting from the real issue?
PJB: There are certainly a lot of misunderstandings about Darwinism, some deliberately fostered by the creationists. For instance, many people think the primary evidence for evolution is the fossil record, which allows the creationists to point to the gaps and say it doesn’t work (although discoveries are constantly filling the gaps in). People don’t remember that it was the geographical distribution of animals and birds that Darwin studied on the Beagle voyage that first made him doubt the fixity of species.
There is also a common tendency to identify evolution with progress, although Darwinism is based on the idea that the driving force of change is adaptation, with progress to higher states as only a rare byproduct. But explaining this only increases some people’s problems because the theory implied that there was nothing inevitable about the appearance of the human race—we are not the intended goal of evolution. There are many liberal religious thinkers who are prepared to accept the general idea of evolution, but find it hard to live with the idea that we are not its goal. They accept that when the Bible talks of “creation,” we have to realize that it was written for people who could not have understood anything like the modern scientific picture of the earth’s history, so the text of Genesis shouldn’t be taken literally. But even so, for God to create us indirectly by evolution, His purpose would have to be manifest in the process. It’s very difficult (although not impossible) to see natural selection as an agent of divine purpose. Hence the enthusiasm for Intelligent Design, although that position simply gives up on the hope of any scientifically verifiable explanation.
Fundamentalism poses a different problem altogether. For those who think the text of the Bible has to be taken literally, the whole scientific picture of the past—not just evolutionism—has to be false. Young-earth creationism insists that the earth is only a few thousand years old. I sometimes wonder why these people bother to attack Darwinism in detail because if they could establish their position on earth-history, any form of evolution would be inconceivable. They pretend their alternative is scientifically viable, but they depend on cherry-picking a few things they can fit into their viewpoint, deflecting attention away from all the evidence that is hard to fit in. Their tactics are partly responsible for the public ignorance of the evidence on the evolutionists’ side.
One interesting development is the emergence of Islamic fundamentalism, which also rejects evolutionism because it’s inconsistent with the creation story in the Koran. Worrying at one level, but the skeptics can now ask the fundamentalists to get their act together and decide which sacred text we’re supposed to take literally.
SC: The first edition of Evolution: The History of an Idea was originally published in 1989, and in the first chapter you state that “Whatever the success of evolution theory in science, the cultural phase of the Darwinian revolution has not yet reached its conclusion.” Almost 25 years later, do you think this is still true? How has the Darwinian revolution progressed culturally since then, and if that progress remains unfinished, how do you see it ending?
PJB: Obviously, to the extent that there is still massive religious opposition to evolutionism, the comments I made back in 1989 about the revolution not being completed are still valid. As long as there are people who feel they have to take an ancient text literally to maintain their faith, the scientific view of earth-history will remain a source of controversy.
SC: One of the major shifts in the Darwinian revolution happened long after Darwin himself had died, with the rediscovery of genetics and trait inheritance in the early 20th century. Culturally speaking, was the union of Darwin’s theories with those of Gregor Mendel helpful for the Darwinian movement? Did people find the idea of evolution easier to accept once genetics entered the picture?
PJB: The emergence of genetics certainly boosted the credibility of Darwinism by supplying a credible mechanism of variation and heredity. But it didn’t do that immediately, and the early geneticists rejected the idea that selection removed harmful mutations. They were, however, opposed to rival theories such as Lamarckism (acquired characters can’t be imprinted on the genes), and by the 1930s, it was being recognized that selection acting on mutations represented the best explanation of adaptive evolution. To the extent that everyone now realizes the importance of genes, Darwinism becomes more plausible. Natural selection explains the constant emergence of bacteria resistant to antibiotics, one of the biggest problems in modern medicine. But the creationists don’t seem interested—to them, they’re just different bugs that have no relevance to the emergence of new species.
SC: Darwin’s theories have had not only religious implications, but also political ones, with some groups applying the concept of natural selection to economics and class struggle. To what extent did this political argument impact the cultural battle over Darwinism and evolutionism as they applied to science? How might Darwin himself have viewed the idea of “Social Darwinism?”
PJB: Most historians accept that Darwin drew some inspiration for his theory of natural selection from the competitive free-market society in which he lived—individuals jockey for position and the losers face serious difficulties. But he didn’t endorse the belief that we should encourage ruthless behavior because he knew that we had evolved as social creatures and have acquired cooperative instincts, which are the source of our moral values. His theory was, nevertheless, used to “justify” various ideologies of social conflict that were called “social Darwinism.” But his theory cannot have been the direct inspiration for these ideologies because they are mutually inconsistent. Some social Darwinists applauded individual competition (free-market capitalism), some opted for national rivalry (militarism), and others for racial struggle (imperialism and colonialism). Darwin was passionately opposed to slavery and held that the human races are all closely related—the claim that the races are separate species with distinct origins was more often supported by creationists and non-Darwinian evolutionists.
SC: Many of Darwin’s pro-evolution followers, including “Darwin’s bulldog” Thomas Huxley, actually rejected Darwin’s theory of natural selection. Why was this? What were their objections to natural selection as a cause of evolution?
PJB: Huxley was a staunch defender of “Darwinism” when the term was still used to denote the general idea of evolution, but he didn’t think natural selection could be a complete explanation because he doubted that adaptation was the most crucial factor. He thought that some form of internal, biological process shaped the variations that appear and hence the route that evolution can take. It can’t be totally non-adaptive, but the routes open to it are restricted by the variations available. The modern proponents of evolutionary developmental biology (evo-devo) opt for a somewhat similar position. Some non-Darwinian evolutionists opted for the Lamarckian theory of the inheritance of acquired characters. In its most basic form that was disproved by genetics, but modern studies of epigenetics suggest that processes superficially similar to Lamarckism may play some role.
SC: Your publications have done a great deal to clarify how Darwinism developed. What are some common misconceptions or inaccuracies you’ve encountered about Darwin’s life and the rise of Darwinism, whether in academia or the public?
PJB: The points I’ve just made illustrate one common misconception—evolutionism isn’t a static, all-or-nothing explanation like creationism. All scientific theories evolve as discoveries are made, and evolutionism is no exception. Creationists claim that because evolutionists are constantly “changing their minds,” it can’t be a proper explanation, but one that just shows how little they understand science. Their approach, especially in its Young Earth version, does have an absolutely predetermined structure into which all the evidence must be fitted—however much twisting that takes. Scientific biologists do research, and if what they discover suggests something new, they incorporate that into the theory. The new ideas don’t overthrow Darwinism, they modify and extend it.
We’ve already covered some other misconceptions. One is the idea that evolution is a theory more-or-less solely based on the fossil record. Fossils are important, and more discoveries are constantly being made that help us see how life evolved, but there are lots of other lines of evidence, including the biogeographical work that so inspired Darwin.
Another popular misunderstanding is the belief that Darwinism is a theory of inevitable progress. Evolution is best represented as a branching tree, not a ladder, and each branch is evolving in its own way. Most adaptive changes are not progressive in any absolute sense, and some are degenerative (as in parasites) or lead into dead-ends where the species cannot respond to any further change in the environment. Human beings cannot be the goal of evolution because we’re just the end product of one branch, and there was no guarantee that intelligent, self-aware creatures would evolve at any point, So evolutionism offers no real guide to future progress—that’s up to us to decide. I realize how hard this vision of the human situation is for many to accept, but pretending that we’ve been given a privileged status by some mysterious Creator doesn’t really help, especially as those who believe in this Creator don’t seem to be able to agree on what He’s really like or which ancient story actually tells us about His purposes.
