Cover image for The evolutionists : the struggle for Darwin's soul
The evolutionists : the struggle for Darwin's soul
Morris, Richard, 1939-2003.
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New York : W.H. Freeman, [2001]

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x, 262 pages ; 20 cm
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QH366.2 .M683 2001 Adult Non-Fiction Non-Fiction Area
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Introduced in 1859, Charles Darwin's theory of evolution generated hot debate and controversy. Today, nearly all reputable scientists agree: evolution did happen and natural selection was its main driving force. And yet, a century and a half after Darwin, the theory of evolution is still being fought over with a ferocity that has rarely been equaled in the annals of science. What are scientists arguing about? And why are their exchanges sometimes so bitter?
In "The Evolutionists," Richard Morris vividly portrays the controversies raging today in the field of evolutionary biology. With a clear and unbiased eye, he explores the fundamental questions about the evolutionary process that have provoked such vehement disagreement among some of the world's most prominent scientists, including Stephen Jay Gould, fellow paleontologist Niles Eldredge, geneticist John Maynard Smith, and zoologist Richard Dawkins.
As he elucidates the issues of contention, Morris also positions them within the broader context of evolutionary thought as a whole. He explains the theory of evolution in detail, reviews the main trends of evolutionary science since Darwin, and assesses how the field is changing today--from ground-breaking new research to the emergence of scientific disciplines like complexity theory and evolutionary psychology.
A vibrant account of contemporary evolutionary biology, "The Evolutionists" is a fascinating look at how controversy and debate shape the scientific process.

Author Notes

Richard Morris lives in San Francisco, California.

Reviews 1

Choice Review

Theoretical physicist Morris explores some current issues of contention in evolutionary biology, with much attention to the personalities involved. He contrasts the various views of evolution put forth by such luminaries as Stephen Jay Gould, Niles Eldredge, Richard Dawkins, Daniel Dennett, and Steven Pinker. Each chapter explores the difference between the reductionist approach, associated with Dawkins, Dennett, John Maynard Smith and others, with the more holistic approach (that complex systems have "emergent properties" that cannot be understood fully using a reductionist approach) associated with Eldredge and Gould. The increasingly caustic nature of the dialog among the scientists is detailed throughout. Four chapters describe traditional Darwinism, followed by chapters on gradualism (including the famous spandrels paper), evolution of complexity, and evolutionary psychology. These are the book's intellectual focus. Two concluding chapters consider current research and offer Morris's opinions. The focus on personalities might give uninitiated readers the sense that the field is totally dominated by a half-dozen individuals, which, of course, is highly misleading. That said, the book is otherwise well written and remarkably concise but would profit from more references. Some of the published research discussed is, unfortunately, not referenced. List of useful Web sites. General readers; lower-division undergraduates. J. C. Kricher Wheaton College (MA)



Chapter One Controversy in Evolutionary Biology According to the noted British geneticist John Maynard Smith, Harvard paleontologist Stephen Jay Gould is "a man whose ideas are so confused as to be hardly worth bothering with." Oxford University zoologist Richard Dawkins, author of the best-selling book The Selfish Gene , charges that Gould's view of evolution is based on a fundamental misunderstanding. Tufts University philosopher Daniel Dennett goes further. According to Dennett, Gould is "a would-be revolutionary" who has mounted a series of attacks on conventional Darwinism over the years. Furthermore, Dennett says, as the best-known writer on evolutionary topics, Gould has had an influence that is "immense and distorting." Gould must have some "hidden agenda," Dennett speculates. Perhaps it is Gould's Marxist leanings, he says, that have caused him to attack accepted evolutionary theory.     Gould, on the other hand, brands Maynard Smith, Dawkins, and Dennett as "Darwinian fundamentalists," who place an emphasis on one component of Charles Darwin's thinking and "push their line with an almost theological fervor." Maynard Smith, he says, has apparently gotten caught up in an "apocalyptic ultra-Darwinian fervor." Dennett's writings, he adds, are characterized by "hint, innuendo, false attribution and error." If the Victorian era British biologist T. E. Huxley had been "Darwin's bulldog," Gould concludes, then perhaps Dennett should be characterized as "Dawkins's lapdog."     Maynard Smith, Dawkins, Dennett, and Gould are not the only individuals engaged in this controversy. For example, Gould's colleague, paleontologist Niles Eldredge of the American Museum of Natural History, has also criticized Dawkins, Dennett, and Maynard Smith. So have various other scientists, such as geneticist H. Alien Orr of the University of Rochester in New York. Evolutionary psychologists such as Steven Pinker of the Massachusetts Institute of Technology and Leda Cosmides and John Tooby of the University of California at Santa Barbara are members of the other camp. The controversy is more than an argument between Gould and his critics. It is one in which numerous scientists are currently engaged because they believe that there are still questions to be settled about the nature of evolution.     Before I go any further, I should point out that none of the participants in this controversy is questioning the idea of evolution. They are all well-known evolutionary biologists with the exception of Dennett, a philosopher who is the author of Darwin's Dangerous Idea , which was a finalist for the 1995 National Book Award. They all agree that the evidence that evolution has taken place is overwhelming, and they all oppose creationism, which they consider to be an attack on science. Furthermore, they all agree that Darwin's idea that natural selection is the main mechanism of evolutionary change is correct. And, of course, they all tend to view themselves as Darwin's intellectual heirs.     What are they arguing about, then? And why have the arguments become so bitter? Those are the questions I try to answer in this book. I think I will be able to show you that there is indeed a lot to argue about and that some of the issues that have been raised are important ones.     Darwin's theory of evolution is universally accepted among biologists. However, Darwin's "theory" is not a single idea; some scientists have broken it down into five or more subtheories. Thus it is possible for scientists to agree on many of the details of the theory while arguing about others. Furthermore, it is possible to agree that natural selection is the main cause of evolution, while debating the details of how evolution has happened. Controversies About the Role of Natural Selection     The idea of evolution was not original with Charles Darwin. On the contrary, it was an idea that had been widely discussed for decades when Darwin published his book On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life in 1859. Darwin's great achievement was to amass evidence sufficient to convince his scientific contemporaries that evolution had indeed taken place, and to suggest a mechanism, natural selection, that would cause species to evolve.     Darwin realized that the members of every species were capable of producing more offspring than could survive. As Darwin noted, this is true even of such slow-breeding species as the elephant. If all the offspring of a herd of elephants lived to maturity and produced offspring of their own, the world would be overrun with elephants in no more than a few thousand years. Darwin reasoned that some members of a species were more likely to survive and reproduce than others. Those that did would pass their characteristics along to succeeding generations. If there was originally a certain amount of variation in a species, some characteristics would be preserved, while others would be weeded out. Over long periods of time the species would change; gradual evolution would take place.     Natural selection does not require that the better-adapted members of a species always survive and reproduce. If they possess characteristics that make survival 1 percent or even a fraction of a percent more likely, then on the average they will have more offspring than other members of the species. Thus ff some of the evolutionary ancestors of the giraffe were able to obtain more food than other giraffes because they had longer necks, then long-necked animals would eventually come to predominate and eventually evolve into the giraffe that exists today. If an antelope could run a little faster than others, it would be more likely to escape predators and reproduce. Its offspring most likely would also be a little faster. Eventually that characteristic would spread throughout the population and in time all antelopes would be swifter.     Natural selection is an idea that is beguiling in its simplicity. Once you understand it, it is easy to become convinced that evolution could happen no other way. However, since the time of Darwin, some scientists have thought that natural selection was not the only driving force behind evolution. In Darwin's day, some biologists thought that there were other important factors. Some of them believed, for example, that some inner force drove human evolution toward greater intelligence. This idea was somewhat metaphysical and today it is thought to be totally discredited. However, scientists have never stopped looking for factors other than natural selection that might influence evolutionary change. I'll be discussing a number of such possibilities in the chapters that follow.     Stephen Jay Gould and his colleague Niles Eldredge are perhaps the best-known scientists who proclaim such a belief. Consequently their names--especially that of Gould, who is the more vocal and contentious of the two--are frequently mentioned by those engaged in the controversies that such ideas have caused. Gould and Eldredge believe that natural selection acting on individual organisms is the main cause of evolutionary change. But they also think that there are phenomena that appear at higher levels of complexity. For example, they have proposed a theory of "species sorting." They claim that, just as some individuals are more likely to survive than others, species also have different probabilities of survival. Furthermore, Gould says, some evolutionary lines give rise to more new species than others. Surely, he suggests, this is a factor in evolution too.     Gould's and Eldredge's theory has been attacked by such orthodox Darwinists as Richard Dawkins and Maynard Smith, who continue to insist that only natural selection is important. In reply, Gould has contrasted Dawkins's and Maynard Smith's "Darwinian fundamentalism" with his and Eldredge's evolutionary pluralism. The controversy is still going on, and it is not likely that the argument will end soon. As I will show later on, the differences between the two groups of scientists do not arise from their interpretations of scientific data. There are fundamental philosophical differences between them. Dawkins, Maynard Smith, and other orthodox Darwinians are reductionists who see only one important factor in evolution. Gould and Eldredge, on the other hand, describe themselves as pluralists who see evolution as something that is much more complex.     The differences in outlook have led to not one but a variety of different controversies. The first one erupted in 1979 when Gould and Harvard geneticist Richard Lewontin published a paper in which they criticized methods that, they claimed, were commonly used by evolutionary biologists. Rather than looking at organisms as integrated wholes, Gould and Lewontin said, these scientists reductively broke them down into collections of individual "traits" and then invented stories that purported to explain why these traits had evolved. But, the two authors said, there was often no evidence to support these sometimes fanciful stories. Gould and Lewontin then went on to maintain that organisms often had traits (which they called spandrels, after the architectural term) that had evolved for no adaptive purpose--in other words, traits that had appeared as by-products of other evolutionary changes.     Naturally, the orthodox Darwinists objected. This was all very well understood, they replied. Gould and Lewontin were setting up a straw man and then knocking him down. In any case, it couldn't be denied that even though spandrels didn't have any functions originally, natural selection could then modify them for adaptive purposes. The point that Gould and Lewontin had made was, in their view, one that wasn't terribly important. Evolutionary Psychology     Eventually the controversy died down. However, the idea of spandrels came to the fore again when Gould began to voice his skepticism about the methods of a new field called evolutionary psychology. Evolutionary psychologists are scientists who attempt to explain human behavior in evolutionary terms. They postulate that the human brain is made up of a collection of "mental modules" that were created by natural selection to cause us to behave in certain specific ways. The evolutionary psychologists claimed to have found modules that produced characteristic human mating strategies, modules that were responsible for cooperative behavior, and so on. Two evolutionary psychologists, Randy Thomhill and Craig T. Palmer, went so far as to maintain that there was evidence that natural selection had produced mental modules that explained male propensity to rape.     The hypothesis advanced by the evolutionary psychologists is not based on any hard neurological evidence. Neurobiology has not advanced to the point where it would be possible to find the neural circuits that correspond to such modules, if indeed mental modules do exist. Thus there is room for controversy. And indeed there has been controversy. Gould in particular has expressed skepticism about the reductionist methods of evolutionary psychology, just as he has objected to what he views as excessive reductionism in the field of evolutionary biology. In his view, human mental functioning cannot be broken down into a collection of distinct traits. He sees the human brain as a kind of general-purpose computer full of spandrels. There was obviously something about the life of human ancestors on the African savannas many hundreds of thousands of years ago, he says, that made big brains advantageous. But once big brains evolved, Gould goes on, they became capable of doing numerous things that were not related to the reasons why natural selection created them in the first place. He points out, for example, that our ability to learn to read and write must be a spandrel. It could not have evolved for some adaptive purpose; when the brain first became large, written language did not exist.     Naturally the evolutionary psychologists did not take kindly to Gould's criticisms. Their replies to Gould have, if anything, been even more bitter than those of the orthodox Darwinists. Some of them have claimed that Gould has misrepresented evolutionary psychology, others have gone so far as to accuse Gould of intellectual dishonesty. This controversy continues to rage with no end in sight. The Sciences of Complexity     Some of the ideas proposed by Gould and hg colleagues are reminiscent of those of the scientists who work in a relatively new field called the sciences of complexity. Complexity scientists come from many different disciplines, including mathematics, physics, computer science, and biology. They work in the field because they have become interested in exploring what are called the emergent properties of complex systems. Complexity scientists maintain that, although reductionist methods are an essential part of science, there are some problems they cannot solve. Complex systems, they say, cannot be reduced to the properties of their components.     Ant colonies provide a good example of this idea. Ants are creatures with simple nervous systems. An individual ant does not have a complex repertoire of behavior, and ants signal one another in only about a half dozen ways. But an ant colony is capable of very complex kinds of activity. Some species of ants, for example, make slaves. Others maintain fungus "farms." Yet others "milk" aphids that they keep as a kind of domestic animal. But these kinds of behavior come about when large numbers of ants interact. The activities of ant colonies, in other words, are emergent properties that are not present in the individuals of which the colonies are composed.     Complexity scientists typically study the systems in which they are interested by modeling them on computers. Computers models of colonies of ants have been created, for example. The behavior exhibited by the "ants" in a computer can be eerily like the behavior of the real insects. Complexity scientists have also created computer models of flocks of birds, hives of bees, and even ecological systems in which one species preys on another. Some of these models have been quite successful. For example, the flocking behavior of computer birds looked so realistic that the program used to create them aroused interest among ornithologists.     Evolving species can also be viewed as complex systems, and some complexity scientists have begun to create computer models that might tell us something about the ways in which evolutionary change takes place. For example, evolutionary biologist Smart Kauffman has created models of networks of genes, and biologist Thomas Ray has created artificial digital organisms that are born, reproduce, mutate, and evolve inside computers.     Some of the work done in the sciences of complexity is as controversial as that done by the evolutionary psychologists. Biologists, in particular, have been skeptical of the idea that computer models can really tell us anything of importance about evolution. Not surprisingly, some of the biologists who have criticized complexity science have been the same ones who have been so vehemently opposed to Gould's and Eldredge's pluralist view of evolution. They have expressed the view that it is possible to get anything out of a computer simulation, depending on what is put into it, and they accuse the complexity scientists of paying little attention to empirical facts. Naturally the complexity scientists disagree. Looking at the Evidence     The recent controversies in evolutionary biology are far from being settled. On the contrary, they are multiplying, and reasoned arguments have increasingly given way to vituperation. One of the reasons is that there has not, been sufficient evidence to answer the questions that have been raised. However, evolutionary biology is anything but a stagnant field. New discoveries are made almost every day. Some of them are beginning to shed some light on the issues that are being argued about. At the same time new questions are being raised.     For example, recent field studies have shown that, in some cases, natural selection is more powerful than even advocates of orthodox Darwinism had believed. Scientists have found that, in some species, observable evolutionary change can take place in as little as ten years. Scientists studying North American fruit flies have recently discovered that flies that migrated to different parts of the hemisphere evolved differences in wing length in only a decade. Furthermore, the differences in wing length matched those of flies that lived under corresponding climatic conditions in Europe.     It has also been discovered that speciation--the creation of new species--does not always happen in the manner that most evolutionary biologists thought it did. It had previously been thought that new species evolved when part of a population became geographically isolated. Since the two subpopulations could no longer interbreed, they would, it was assumed, evolve in different directions. However, biologists conducting field studies have recently discovered that populations that are not separated by geographical barriers often split into two different species by adapting themselves to different environments. This has been observed, for example, in stickleback fish living in Canadian lakes. In a number of different locations, similar but distinct species evolved when some of the fish continued to swim in open water, while others became bottom dwellers.     Finally, contrary to what had previously been thought, it appears that evolution does not invariably take place through the gradual accumulation of numerous small, favorable mutations. It has been shown that sometimes new species are created when a small number of genetic mutations have large effects. This has been seen, for example, in fruit flies on an archipelago in the Indian Ocean and in monkey flowers growing in California.     Some of these discoveries are so recent that it is not clear what their implications will be. But if I had to make a guess, I would say that ten years from now evolutionary biologists will still be arguing, most likely about different things. New evidence about evolution is accumulating. Some of it is so surprising that it is likely that new theories will have to be developed to explain it. And theories are something to argue about.     I expect that, in the years ahead, evolutionary biology will become even more of a contentious field than it is now. But of course there is nothing wrong with that. Scientific controversy, though it may be bitter at times, is a healthy thing. It is a sign that scientists are questioning old ideas and looking for ways to better understand existing evidence. Scientific controversy is a sign of vitality. The absence of scientific controversy in a scientific field is a sure sign that few further advances will be made. For example, no one argues about planetary motion anymore, or about how a lens focuses light. The significant questions about those matters were settled long ago, and there is nothing more to add.     Science, in other words, is a quest for knowledge. And when new discoveries are made, it is only natural that scientists should argue with one another about what they have found.     I will be discussing these and other controversies in the chapters that follow. Then I will talk about some of the new evidence concerning evolution that is appearing. But before I do either, I think it would be a good idea to discuss Darwin's theory and the evidence for it in some detail. I will talk about the various subtheories that make up "Darwin's theory of evolution" and try to give you some of the ideas that seem firmly established and that seem to allow for different interpretations. After all, to follow an argument, it is necessary to understand what is being argued about Fortunately the relevant ideas are simple ones, and it won't be necessary to devote a great deal of space to explaining them.     I will begin discussing the current controversies in evolutionary biology in Chapter 4. Since there are quite a number of them, discussions of them will constitute the bulk of this book. Finally I will talk about some of the new discoveries that have recently been made. Copyright © 2001 Richard Morris. All rights reserved.

Table of Contents

Prefacep. vii
1 Controversy in Evolutionary Biologyp. 1
2 The Fossil Record and the Evidence for Evolutionp. 13
3 Darwin's Five Theories of Evolutionp. 47
4 Darwinian "Fundamentalism"p. 75
5 How Gradual Is Evolution?p. 99
6 The Sciences of Complexityp. 125
7 Evolutionary Psychologyp. 157
8 The Evidencep. 195
9 Controversy and Discoveryp. 225
A Selected, Annotated Bibliographyp. 239
World Wide Web Resourcesp. 245
Indexp. 252