RNCSE 23 (2)

Reports of the National Center for Science Education
Volume: 
23
Issue: 
2
Year: 
2003
Date: 
March–April
Articles available online are listed below.

Paradigm Glossed: How to Make an ID Debate Worthwhile

Reports of the National Center for Science Education
Title: 
Paradigm Glossed: How to Make an ID Debate Worthwhile
Author(s): 
Clay Farris Naff and Jim Bechtel
Center for the Advancement of Rational Solutions
Volume: 
23
Issue: 
2
Year: 
2002
Date: 
March–April
Page(s): 
7-8
This version might differ slightly from the print publication.
The firefly (Photuris pyralis) is a wonder of nature. Its tiny body contains luciferin and luciferase, two rare chemicals that scientists have been unable to synthesize. Yet, as any child who has grabbed one of the slow-flying insects on a summer evening knows, those substances produce a remarkable and beautiful phenomenon: cold light.

Curiously, Photuris pyralis never came up in the Great “Intelligent Design” Debate held at winter’s end at Saint Paul United Methodist Church of Lincoln, Nebraska. Yet, somehow, the debaters — philosopher Paul Nelson of the Discovery Institute and evolutionary biologist Massimo Pigliucci of the University of Tennessee — managed to mimic the firefly’s trick: they cast much light with little heat.

Over the span of nearly two hours, they offered arcane details of biology and earthy, sometimes humorous presentations of their arguments. In the end, they inspired the Center for the Advancement of Rational Solutions (CARS) to consider new ways of resolving the public policy impasse over the science curriculum.

Considering the unsavory history of creationism/evolution debates, this amounts in our view to a minor triumph. And yet nothing miraculous took place. On the contrary, we believe what transpired in Lincoln could be replicated — with variations — around the country. To that end, we would like to share the story of our event and insights about what made it work. The debate centered on the question: “Is ‘intelligent design’ a valid scientific alternative to evolution?” At the start the audience of some 150 people who braved a blizzard to attend were told that although this was to be a debate, “the only winner will be those of you who are willing to consider a point of view or information you haven’t thought about before.”

That position was in keeping with our group’s outlook. Although the leadership of CARS is solidly in the evolutionary camp, the organization exists to promote rational reconciliation of religions with science and with each other. Its membership includes a variety of creationists, from biblical literalists to nonspecific ID advocates, whose views are welcomed within the group’s discussions.

Talking Points

The debate opened with PowerPoint presentations from each side. Nelson, who holds a doctorate in philosophy from the University of Chicago, surprised many by conceding from the start that, strictly speaking, “intelligent design” is not a valid scientific alternative to evolution — at least not yet. “Intelligent design”, he admitted, has yet to demonstrate its validity or to be accepted by the majority of the world’s scientists. However, he argued, the really fruitful questions concern the nature of science. Its commitment to methodological naturalism, Nelson said, “leaves you with only that one tool in your kit.” Science would be “more honest” without this unnecessarily restrictive rule, he said.

Nelson introduced one of ID’s two main arguments with a humorous anecdote about “Mint Jelly Ridge”, a con man who faked injuries by pretending to slip on mint jelly in restaurants throughout the Midwest. Insurance companies who paid claims on behalf of restaurant owners detected a pattern that indicated design rather than accident, leading to Ridge’s arrest and conviction. This, Nelson said, was an example of the design inference, something routinely used in forensics and a method that Nelson’s Discovery Institute colleague William Dembski claims should be applied to features of nature.

In his presentation, Pigliucci offered a definition of biological evolution as both change in the frequency of genes and, historically, as the descent of species from common ancestors along the “tree of life”. He took pains to exclude the origin of life from evolutionary theory. Pigliucci defended evolution on the grounds that it offers a coherent explanation for our observations of biological diversity, and it makes predictions that can be empirically tested.

In contrast, he said, “intelligent design” offers only flawed arguments with no predictive value. Taking on one of these — Michael Behe’s argument for the “irreducible complexity” of certain microbiological features — Pigliucci said that it amounts to an “argument from ignorance”. If something cannot be explained by evolution at present, he said, some would have us believe that it must have been intelligently designed. Such a strategy, however, consistently fails as science progresses, he argued.

By the same token, “intelligent design” advocates should be prepared to explain numerous instances of poor design in nature, Pigliucci asserted. He offered the example of rabbits that depend on certain bacteria in their guts to supply necessary digestive enzymes. Unfortunately, Pigliucci said, the rabbits have no means to pass on the bacteria except by having baby rabbits eat their mother’s feces. He added that biological relatives of rabbits do have genes that produce the enzyme directly, so evolutionary theory would predict that remnants of the genes still exist in the rabbit, and, sure enough, Pigliucci said, the pseudogenes have been found.

Give and take

Up to this point, the arguments would have been familiar to anyone acquainted with ID–evolution disputes. Things got more interesting, however, when the debate moved into its free-flowing discussion phase. Nelson raised “Clarke’s Law” , the acclaimed science-fiction writer’s dictum that any sufficiently advanced technology would appear to be magic to a less advanced civilization. He asked Pigliucci how Aristotle would have explained a television remote control. His opponent responded that Aristotle would have assumed a naturalistic explanation: a supernatural explanation cannot be tested, he said. Nelson responded by musing on whether “supernatural” remains a useful category. Perhaps it is time to move beyond that concept and make testable predictions outside the bounds of naturalism, he suggested.

Later, Nelson raised a possibility for a specific ID prediction. Referring to “orphan genes” occurring uniquely in some microorganisms without analogs in related species, he said that ID advocates should be prepared to predict that similar anomalous genes will be found scattered throughout the zoological realm. He also pointed to the origin of life as a focus for ID. Reasoning that RNA could not have held together long enough to give rise to life, Nelson speculated that the fragility of RNA could be a “signature” of the intelligent designer. Pigliucci replied that the frequency of “orphan genes” is well within the limits of random phenomena, and that RNA’s fragility might have been solved by the “pizza model” of biogenesis, in which organic chemicals are thought to have self-assembled within stable films on rocks.

Self-critique

Most interestingly, each debater offered an unsolicited criticism of his own side. Pigliucci denounced “scientism” — the claim that science can eventually answer all questions — as indefensible arrogance. Nelson declared that teaching “intelligent design” in science classes would be wrong at this stage. Philosophy courses are the proper venue for the study of ID, he added, until it proves itself scientifically valid. This willingness to be self-critical and to trust in the civility of the other side contributed greatly to the thoughtful atmosphere. To be sure, there were skeptical and even emotional reactions from audience members during the question-and-answer segment that closed out the debate. But on the whole, it was a refreshingly high-minded occasion.

The lion’s share of credit goes to the debaters themselves, who eschewed rhetorical tricks, distractions, and combativeness in favor of a serious, accessible consideration of the issues. Still, the structure and sponsorship of the debate undoubtedly helped. Putting the focus on “intelligent design” helped to prevent the debate from becoming a mere rehearsal of attacks on evolution (not that Nelson would necessarily have conducted himself that way).

Response to the debate was uniformly positive across the ideological spectrum. At the request of members, the next meeting of our organization was devoted to follow-up discussion. Three members requested time to offer brief prepared presentations. Two were defenses of evolution, while the other was a defense of “intelligent design” and a call for opening up the public school science curriculum to alternatives on the grounds of democracy.

Interestingly, in the ensuing discussion, considerable support emerged for the idea of teaching “intelligent design” — but not in science classes. Rather, there appeared to be support in the group for the idea of introducing philosophy of science and religion classes into the public school curricula alongside regular science classes. With appropriate safeguards on neutrality concerning religion, this might represent an avenue to reconciliation, with the added benefit of exposing students to philosophical discourse and critical thinking at the high school level.

Call it the firefly option.

About the Author(s): 
Clay Farris Naff and Jim Bechtel
Center for the Advancement of Rational Solutions (CARS)
649 S 18th Street, #31
Lincoln NE 68508

Review: In Darwin's Shadow

Reports of the National Center for Science Education
Volume: 
23
Year: 
2003
Issue: 
2
Date: 
March–April
Page(s): 
36–37
Reviewer: 
Aubrey Manning
This version might differ slightly from the print publication.
Work under Review
Title: 
In Darwin's Shadow: The Life and Science of Alfred Russel Wallace
Author(s): 
Michael Shermer
New York: Oxford University Press, 2002. 422 pages.
Opening this book, I had a quibble about its title. Is Alfred Russel Wallace really such an unfamiliar figure today? Was he seen by his contemporaries as overshadowed by the great man? I am not sure. Indeed, Shermer’s account of his later life reveals how much Wallace stood out then — he became recognized, at least in Britain, as “the last of the Great Victorians”. In part this was a result of his remarkable longevity, for he lived on to the age of 90 (until the end of 1913). Remarkable is the right term because during his extended expeditions to the Amazon and the Malay archipelago (modern Indonesia), he was frequently brought to death’s door by malaria, yellow fever, and many other tropical plagues. He must have had the constitution of the proverbial ox!

This is a distinguished and scholarly biography with excellent coverage of the science. Shermer is concerned with the history of evolutionary ideas and uses the interaction between Wallace, Darwin, and others to great effect. He goes beyond this to examine the extraordinary range of Wallace’s interests and how they came to dominate different stages of his life. It is always clear and attractively written but is very detailed in places and probably not best suited for non-specialists wanting an introduction to Wallace’s life. They might first go to Peter Raby’s very good Alfred Russel Wallace: A Life (Princeton: Princeton University Press, 2001; reviewed by John Wilkins in RNCSE 2003 Jan/Feb; 23 [1]: 39–40), but it is to Shermer one must go to dig deeper.

Wallace had little of Darwin’s science background in his family nor the privileges of money. He was eighth-born into a family that never had much to spare. He had little formal education but considerable opportunity for reading and inquiry. He had quickly to earn a living and did a little teaching, then spent a few years as a surveyor working for the burgeoning railway companies. In view of what came later, it is interesting to note that very early on he came to abandon conventional religions as poorly equipped to explain the phenomena of nature. Also, he and a brother attended evening classes in one of the “mechanics’ institutes” where working people could learn science and some philosophy. Wallace was here introduced to the socialist ideals of Robert Owen, the founder of New Lanark. But from his earliest days he loved an outdoor life; he was captivated by the natural world and became a very acute observer. He met up with HW Bates, a young man of very similar tastes, and together they planned a major expedition to the Amazon basin, to be financed entirely from the collections they would make. This set the form of all Wallace’s early career: his fascination with the variety of life provided his delight, his intellectual challenge, and his livelihood!

He was quite early in correspondence in Darwin, who recognized that the revelation of the huge variety of species Wallace was describing from the tropics and their geographical distribution were of great significance. Indeed, they began to throw some light on “that mystery of mysteries”, as Darwin described the origin of species in the introduction to his crucial volume. It was clear that Wallace himself was musing on that mystery, and Darwin probably knew this. Then came the bombshell of a letter he received in June 1858 sent from the remote East Indies. Wallace there set out ideas on natural selection and its operation virtually identical to those which Darwin had been painstakingly developing over the 20 years since he returned from the voyage of the Beagle.

The story of how Darwin and Wallace came to publish a joint paper in that year and how Darwin subsequently accelerated into action over the Origin is now fairly familiar. It has aroused bitter accusations of plagiarism from those — and there are always iconoclasts among us — who accuse Darwin of deception at Wallace’s expense. Shermer provides here a most detailed and sensitive analysis of those crucial months and all that has been written about them. He totally acquits Darwin, clearly believing that he was basically a nice person, and I totally agree with him! Darwin often acknowledges the extent of Wallace’s contribution, particularly in relation to the geographical distribution of animals and plants, which lent powerful support to evolutionary ideas. There is certainly no sign that Wallace ever felt a trace of resentment. He obviously admired Darwin and throughout his long life continued to refer to him and promote the concept of natural selection. He remained extraordinarily modest and self-effacing about his achievements. It was quite a struggle for his colleagues to get him to accept election to the Royal Society of London, for example.

Wallace’s one departure from Darwin and from the power of natural selection concerned the human brain, which he believed forced him to accept a designing force beyond nature. Why else would “savages” be already in possession of a brain identical to that of the more civilized when only the latter uses its amazing capacities to the full extent? Alas and alas, I feel! How could Wallace, who was such an acute observer, not recognize the scope of the civilizations around him as he moved through the Malay archipelago? But then even the greatest people have blind spots. Darwin remained convinced that natural selection was behind it all, but even he found it hard to credit that he was from the same species as the natives of Tierra del Fuego!

Certainly Wallace pursued various potty ideas such as spiritualism in the latter part of his life. He clearly lacked judgment in some cases; Shermer relates the comic story of Wallace’s attempt to win 500 pounds (which he probably needed — he was never flush with funds!) from a wager offered by a lunatic who believed the earth was flat. Careful measurements were made along a 6-mile, dead-straight stretch of canal. The curvature was clear, but no money was forthcoming, nothing but a stream of insulting and threatening correspondence and bills from lawyers.

Nevertheless, Wallace was also seriously involved with the betterment of human societies and retained his youthful allegiance to socialist ideals. He was extraordinarily productive on a variety of issues. What other biologist would have contributed books on Land Nationalisation and Social Environment and Moral Progress among all the extensive biological work! Shermer provides a full bibliography of Wallace, which in itself is a remarkable record of a remarkable and admirable man. The book is well-illustrated and includes some delightful photographs of Wallace as an old man. There is one of him, near the end of his long life, resting on the ground in the sunlight of a woodland path, still delighting in the natural world. It is one of many images from this excellent biography I wish to retain.

About the Author(s): 
Aubrey Manning
ICAPB
Ashworth Labs
West Mains Road
Edinburgh EH9 3JT
United Kingdom

Review: Species of Origins

Reports of the National Center for Science Education
Volume: 
23
Year: 
2003
Issue: 
2
Date: 
March–April
Page(s): 
36–37
Reviewer: 
George E Webb, Tennessee Tech University
This version might differ slightly from the print publication.
Work under Review
Title: 
Species of Origins: America's Search for a Creation Story
Author(s): 
Karl W Giberson and Donald A Yerxa
Lanham (MD): Rowman & Littlefield Publishers, Inc, 2002. 277 pages.
The continuing controversy over the teaching of evolution in the public schools has undergone various transformations during the last century. From the post-World War I campaign of William Jennings Bryan through the creation science movement of Henry Morris to the "intelligent design" efforts associated with Phillip E Johnson, opposition to the inclusion of evolutionary concepts in the science curriculum has remained a constant in recent American history. Emphasizing the constancy of anti-evolution sentiment, however, can lead to the conclusion that a monolithic movement seeks to remove Darwin from the public schools. A closer analysis reveals a far more complex situation.

The authors of Species of Origins (one a physicist, the other a historian) provide an overview of the various ideas behind the evolution/creation debate in the United States in an effort to clarify our understanding of this long-standing controversy. Following an introduction in which they stress their goal of a fair and balanced treatment of the various creation explanations (thus, species of origins), they provide a brief overview of the evolutionary explanation accepted by the scientific community. Specialists in the various disciplines they survey will, to be sure, blanch at the authors' discussions of such complex topics as the physics associated with the immediate aftermath of the Big Bang and the origin of life on earth, but the non-specialist will at least be exposed to important concepts. The authors end this chapter by emphasizing that despite the widespread acceptance of the evolutionary account by scientists, opinion polls consistently indicate that the public largely rejects this explanation.

Once the dichotomy between the scientific and public perspectives on origins is identified, they take the logical next step and rigorously analyze the different explanations offered by opponents to evolution. In an extensive and well-informed discussion of the creation science movement of Henry Morris and his colleagues, they emphasize that this version of anti-evolution sentiment must be examined within the scientific, religious, and social contexts of the movement. The literalistic reading of the Bible and the deeply-held concern about the decay of traditional morality are as important to the creation science perspective as is its focus on a 6-day creation and a global flood. The authors provide a carefully crafted discussion of all 3 contexts and are especially effective in describing the scientific arguments used by these creationists.

The authors make clear, however, that religious aspects dominate creation science. The importance of religion to creation scientists is in stark contrast to the situation among natural scientists, at least among those most active in the popularization of the evolutionary world view. In an intriguing chapter, the authors discuss the work of several popularizers, including Richard Dawkins, Steven Weinberg, Stephen Jay Gould, and others. Although they emphasize that a wide range of attitudes toward the science/religion clash exists among such popularizers, the authors conclude that traditional religion has no role to play in the popularizers' perspectives. The overt atheism of Dawkins is countered by the sense of loss Weinberg expresses over the lack of purpose in modern views of the universe, but persons of faith often find no significant difference between the two views. Gould's suggestion that science and religion work best when each restricts its focus to its own separate sphere works no better. The scientific sphere is concerned with facts, in his view, while the religious sphere is concerned with ethics and morality. To suggest that religion has nothing to do with "truth" is hardly a concept likely to attract support from the religious community.

Is there a middle path? The authors devote the remainder of their book to an examination of possible alternate explanations that would maintain both scientific and religious integrity. Such concepts as the gap and day/age models of creationism (rejected by Morris and his followers), as well as various versions of theistic evolution, are all described in sufficient detail to show the reader how complex the middle way might be. In the same category is the most recent of anti-evolution efforts, the "intelligent design" movement. The authors devote the last two chapters to this concept and its reception, providing a sound overview of the ideas involved in this latest challenge to Darwin.

The great strength of this book rests in the authors' decision to take the continuing evolution/creation debate seriously. They thus accept that any study of this topic must take the various components of the debate seriously, as well. Readers who want a balanced account of the various modes of anti-evolution sentiment of the past half century will find in Species of Origins a valuable introduction to an intriguing cultural phenomenon.

But is it possible that the authors have taken these anti-evolution views too seriously?

In their introduction, the authors acknowledge that they have accepted the postmodern view of the supposed clash between science and religion and have embraced the "methodological agnosticism" (p 10) of historian Ronald L Numbers in an effort to provide a more accurate view of the debate. Such earlier concepts as a "warfare" between science and religion have largely been abandoned by historians of science, who now stress that the relation between the two throughout history has been much more complex than the earlier metaphors implied. Thus, creating a dichotomy between the "progressive" world of science and the "reactionary" world of religion is both inaccurate and counterproductive. Far better, the authors emphasize, to treat the creationists with the same intellectual respect as the scientists.

This is an admirable goal, to be sure, but it guides the authors into the postmodern muddle of the "science studies" perspective, in which the concept of an accurate portrayal of nature is an illusion. Consider the subtitle of this volume: "America's Search for a Creation Story [emphasis added]". The chapter in which they summarize the modern scientific explanation of origins carries the title, "The Modern Creation Story [emphasis added]". The authors emphasize frequently the need for a creation "story" for all cultures, ancient and modern, and stress that the current debate shows that such a need continues in the early 21st century. Thus, American society seeks a "story" that will satisfy a deeply rooted cultural need.

The difficulty, of course, comes when there are two competing stories, one of which is largely based on a religious world view and the other largely based on a naturalistic world view. To determine which is "right", one needs to be able to evaluate the evidence presented in support. Is such evaluation taking place in contemporary America? If so, the question posed early in the authors' discussion takes on added significance: Why is it that most Americans reject the scientific explanation of origins?

The answer is embedded in the postmodern perspective the authors embrace. It is another example of the contemporary rejection of expertise that has increasingly guided discourse and decision-making over the last few decades. If we are dealing with different "stories", then does that not suggest that all "stories" are more-or-less acceptable? Or do we appeal to an "authority" who might have special expertise? This latter solution seems to be absent from non-evolutionary explanations of origins. Phillip E Johnson, the acknowledged founder of the "intelligent design" movement, plays a major role in the authors' discussion of contemporary anti-evolution sentiment. His credentials for offering a challenge to evolutionary explanations include his status as "a brilliant Berkeley law professor" (p 198), his academic position as "a recognized authority in criminal law and a tenured professor at Boalt Hall, the prestigious law school of the University of California at Berkeley" (p 200), and his ability to read popularizations of evolutionary theory "carefully through the eyes of a lawyer" (p 200). The publication data of most of the authors' cited references concerning anti-evolutionary ideas include the names of very few major publishers; most of these works have been published by religious publishing houses or in journals outside the academic mainstream. In short, those who seem to be the leading figures in the anti-evolution campaign (whether in creation science or "intelligent design") rarely have the background one would expect from individuals who are challenging one of the best established scientific concepts of the contemporary world.

Despite the authors' careful and balanced discussion of the various modes of thought concerning creation, in the final analysis their "story" suffers from a willingness to accept that scientists have no privileged position in crafting explanations of the natural world. A lawyer and a biologist are on equal footing when they attempt to offer explanations of the origin and development of life on earth. Surely, such a perspective carries the concept of "fairness" well beyond its proper role.

About the Author(s): 
George E Webb
Department of History
Tennessee Tech University
Cookeville TN 38505

Strategies to Help Students Change Naive Alternative Conceptions about Evolution and Natural Selection

Reports of the National Center for Science Education
Title: 
Strategies to Help Students Change Naive Alternative Conceptions about Evolution and Natural Selection
Author(s): 
Marshall D Sundberg
Emporia State University
Volume: 
23
Issue: 
2
Year: 
2003
Date: 
March–April
This version might differ slightly from the print publication.
[S]tudents’ initial qualitative, common sense beliefs ... have a large effect on performance ... but conventional instruction induces only a small change in those beliefs ... the basic knowledge gain under conventional instruction is essentially independent of the instructor (Halloun and Hestenes 1998).
This statement summarizes the outcomes of numerous studies on student learning that suggest a change in teaching methodology is critical to achieving a greater degree of scientific literacy among our students (Hake 2000; Mintzes and others 1998; Udovic and others 2002). Although this statement is a recognition of the constructivist philosophy of learning, it also acknowledges a more specific problem relating to many basic scientific concepts. For biologists, the most notable among these are evolution and particularly natural selection. Students bring many naive beliefs about evolution to the classroom, which are particularly resistant to change through traditional instruction (Sundberg 1997).

The purpose of my ongoing research in biological education is to identify and describe teaching strategies that are effective against such entrenched beliefs and that will promote a more sophisticated understanding of basic concepts. In this paper, I summarize the results of my most successful interventions to address (1) major concepts related to evolutionary theory and (2) concepts related to the nature of science.

The Course

Most of the investigative exercises described below have been used in an independent college introductory biology laboratory course, paired with a traditional lecture, but the greatest student gains were observed when “lecture” and laboratory were integrated into a single course. Students were a mix of biology majors and non-majors. The course was scheduled for two 3-hour blocks per week. This intensive block format allowed for great flexibility in varying the time commitment to a variety of pedagogical techniques and particular concepts. Five readings were used in lieu of a textbook: Lives of a Cell (Thomas 1974), The Cartoon Guide to Genetics (Gonick and Wheelis 1991), Darwin for Beginners (Miller and van Loon 1982), Ever Since Darwin (Gould 1977), and Ecological Vignettes (Odom 1998). A variety of “majors’” textbooks was also available for use in class or for checkout for use as an encyclopedic reference as needed.

The primary instructional technique was a Socratic dialog based on daily readings. These discussions were also used to introduce specific problems for laboratory investigation. For instance, Darwin’s response to tropical diversity in the Amazon is used as a lead-in to the investigation on variation. The technique of concept mapping (Novak and Gowin 1984) is introduced early, primarily as a tool to identify questions for investigation. In a completed concept map, virtually every connector between concepts identifies a testable hypothesis. The class is divided into research teams the first day; these teams collaborate on investigations throughout the semester. Considerable peer instruction takes place during the performance of investigations and as results are reported to the class.

Controls for this study included traditional majors’ lecture and laboratory, traditional non-majors’ lecture and laboratory, traditional majors’ lecture and investigative laboratory, and traditional non-majors’ lecture and investigative laboratory.

The investigations dealing with evolution began with a passage from an 18th-century evolutionist’s theory of evolution (Lamarck 1809, in Ames and Siegelman 1966: 28–9). I purposely chose Lamarck as an entry into the theory of evolution because most beginning students who express any belief in evolution actually have a Lamarckian understanding of the process. This is a starting point to which students can relate but which ultimately leads to results that students must reject. In this passage, Lamarck contrasts his theory with the dogma of special creation. Students read the passage, underlining key words and phrases. As a class we then construct a concept map of Lamarck’s theory and identify possible points of testing. Figure 1 is a simple concept map of our current understanding, with the three concepts identified by Lamarck in boldface. These three concepts are the focus of investigation.

Figure 1. Concept map of evolutionary theory with concepts identified from Lamarck reading in boldface

Variation

The null hypothesis, based on Lamarck’s text, is that species tend to be perfectly adapted to their particular circumstances, so there should be no significant variation among them in observable features. I present the research teams with a tin of either pecan fruits or sunflower seeds and challenge them to design an experiment to test the null hypothesis. Each team must formulate a research plan and have it approved before beginning the experiment. A variety of measuring instruments is available in the laboratory, including metric rulers, vernier calipers, graduated cylinders, and balances. (Students are familiar with each of these tools from their earlier investigation of accuracy and precision in measurement and basic descriptive statistics.) Typical parameters chosen for investigation include length, width (there are several sampling questions here such as where to measure, whether to choose maximum or minimum, and so on), mass, volume, and color pattern. Research teams must graph and interpret their data.

Figure 2. Summary student data of variation in seed length and seed mass
Figure 2 summarizes data from two student groups, one measuring seed length and the other seed mass. For comparison, the data are standardized into size classes. These data are representative of typical student results and were chosen to show two very different, yet common, patterns that students will discover. In both instances, evidence of variation in the chosen character is measurable and distinct. In the case of length, variation approximates a normal distribution, with the majority of individuals found in size class four. Similar distributions generally occur for width and volume. Seed mass exhibits more variability and in this case is almost evenly distributed among the size classes. Color pattern in sunflower seeds would be similar.

Several questions typically arise as individual research teams present and discuss their data. For instance, given the data discussed above, teams may question whether the observed variation is significant. Some may argue that the observed variation in length is so small as to be unimportant, and thus the data do not falsify Lamarck’s theory. This provides an opportunity for introducing the idea of a statistical test of an evolutionary hypothesis. Another common question concerns the presence or absence of what might seem a plausible correlation. In the above example, most students expect that longer seeds (or seeds of greater volume) would necessarily have greater mass. Here is evidence that what seems plausible is not always substantiated by data. Other unknown factors, in this case degree of hydration, may influence the data. These data can also be used to introduce the idea that the variation on which natural selection will work is random and does not arise to meet a specific need or purpose. Importantly, the variation investigation is simple and can be completed in one class period. A general characteristic of effective strategies for modifying ingrained misconceptions is that the tasks have simple manipulations and are of short duration (Sundberg and Moncada 1994).

Selection

Selection of existing characters is a key component of evolutionary theory; the testable null hypothesis is that the frequency of a specific trait in a population cannot be altered in subsequent generations by selection. For this investigation, we use two populations of fruit flies (Drosophila melanogaster) — wild-type “fliers” and vestigial-winged “crawlers”. After the class has had an opportunity to examine individuals of both populations, the research teams are divided into two groups. The teams in one group are challenged to test if the wild-type phenotype can be selected for; the other teams will attempt to select for the vestigial-winged phenotype. Although two or more teams are faced with the same challenge, each team must design its own experiment and have it approved before it can proceed. In the laboratory, I provide fly populations, flynap (used to anesthetize the flies), fly medium, and 2-liter plastic bottles. Each research team must provide any other additional materials it will need for its experiment. Typical materials include threads to suspend small containers of medium, straws, double-sided tape, flypaper, water moats, petroleum jelly, and external light sources.

Teams typically begin by introducing equal numbers of male and female flies of both phenotypes into their experimental and control chambers. (Most of the bottles can be hung in the room for decoration once they are set up.) During subsequent class periods, teams examine and take notes on the flies in their bottles. Although differential mortality can often be observed quite quickly, the experiments are allowed to run until the flies have produced at least their first generation of offspring.

Table 1
Sample Student Data for Fruit Fly Selection

None (control)For FliersFor Crawlers
FlierCrawlerFlierCrawlerFlierCrawler
Start101010101010
End15838245788123
Caught in Flypaper624

Table 1. Summary student data of selection for wild-type (flier) and vestigial-winged (crawler) fruit flies.

Table 1 illustrates typical results, from which we draw several important conclusions. The wild-type group is usually pleased by its success in selecting for fliers; selection can alter the frequency of a trait in later generations. But when challenged, these students realize that a significant number of vestigial-winged flies also reproduced. Under these conditions, the fliers were more likely to survive and reproduce, but the selection pressure was not so intense as to prevent vestigial-winged flies from reproducing, too.

Selection for vestigial-winged flies is usually less successful. Invariably there will be more flier offspring (which were selected against) than crawler offspring (which were selected for). The obvious explanation for students is that these teams were not successful in designing traps or obstacles that could effectively keep fliers from reaching a food source while permitting crawlers to feed. But these results, along with the control, also can be used to make the point that things are not always as simple as they seem. In fact, this provides the lead-in to a section on genetics. After studying Mendelian genetics, students are asked to re-analyze their fly data to see whether there might be some alternative explanations for their results. For instance, could a crawler mate with a flier? If so, what would be the phenotype of their offspring?

Adaptation and Heritability

These concepts also appear on the students’ concept maps of Lamarck’s theory. The null hypotheses are that organisms will not exhibit adaptation to environmental perturbation and that even if adaptions are evident, they will not be heritable. Perhaps the most common misconception about the mechanism of evolution is that individually acquired adaptations can be passed on to offspring. Therefore, this investigation is critical in helping students to develop a more sophisticated understanding of natural selection.

Research teams are provided with seeds of Wisconsin Fast PlantsTM and asked to design an experiment to test the hypothesis concerning adaptation to the environment. Fast PlantsTM are a particularly useful organism for this study because of the variety of characters that can easily be quantified: for example, number and size of leaves, number and size of internodes, overall length, and a variety of anatomical surface features such as hairs and stomata that can be sampled non-destructively. In addition, a variety of environmental treatments can be employed without concern for pain to the organism. Plants show much greater developmental plasticity in response to environmental factors than do animals. Finally, the life cycle is rapid enough that the treated generation can produce seeds that can be grown out in a second generation to test for heritability.

We usually begin by listing on the board as many environmental parameters as possible that might affect plant growth. Research teams are then asked to choose one parameter and design an appropriate experiment to test for an adaptive response. Variables involving light and water are the most commonly chosen, including light intensity, light quality (color), light duration, quantity of water applied, and substances added to water. Each team must investigate a different parameter and all research plans must be approved before the investigation can begin.

One of the more interesting student-designed experiments investigated the effect of gravity on stem growth. In this investigation, Fast PlantsTM were grown in square styrofoam cubes that can easily be laid on their side; the experimental cubes were placed on their side as soon as plants germinated — a period of about 3 days. Every day thereafter, the cubes were rotated to the next side so that, at the end of a week, there was a full rotation. The plantlets developed with a “corkscrew” phenotype. The controls were grown in the upright position.

Table 2A
Sample Student Data for Spiral Phenotype
Original "Treated" Generation

TreatmentDay 2Day 4Day 6Day 8
Upright Plants0000
Plants Rotated on Side0246

Table 2B
Sample Student Data for Spiral Phenotype
Offspring Generation - Grown Upright Only

TreatmentDay 2Day 4Day 6Day 8
Offspring of Upright0000
Offspring of Rotated0000

Table 2. Summary student data of heritability of adaptation to an environmental factor

The results of this experiment are shown in Table 2. The number of leaves produced in a spiral gyre were counted as “spiral revolutions”. Under optimal conditions, approximately one leaf is produced per day and thus each new leaf produced when a plant is oriented horizontally will be in a spiral gyre. The null hypothesis — that there is no phenotypic effect from the changing orientation to the force of gravity — must be rejected because of the obvious response of the plant to its horizontal rotation.

This was a particularly interesting experiment because a complex phenotype was produced that mimics the growth pattern of certain horticultural varieties such as the corkscrew willow. However, this adaptation cannot be inherited. Seeds from the treated plants, when grown in “normal” position, retain the normal upright growth pattern. Individual adaptation to the environment is not natural selection! Individuals can alter their form or behavior, to a limited degree, in response to their environment, but they cannot change their inherited characteristics.

Assessment of Effectiveness

The assessment items used in this study are drawn from instruments used in previous work (Sundberg 1997; Sundberg and Dini 1993; Sundberg and others 1994; Sundberg and Moncada 1994). To standardize the results, only scores on identical items, specifically targeted to common and persistent misconceptions, are reported here. The Integrative/Investigative category represents 3 pooled sections; the Majors’ Investigative Lab/Traditional Lecture category represents 4 pooled sections; and all other categories represent pools of more than 10 sections. In the previous work cited above, majors’ pre-test scores tended to be slightly higher than those of non-majors, but these differences were not significant. This pattern continues to hold true.

There is a consistent tendency for investigative instruction, integrating lecture and laboratory, to be more successful in promoting student understanding of the nature of science and the theory of evolution than traditional lecture/laboratory or traditional lecture/investigative laboratory. Figure 3 illustrates scores on a content post-test given at the end of the semester. Pre-test scores were in the range of traditional lecture/laboratory post-test scores. Virtually no change was observed in these classes between pre-test and post-test scores. In all four categories examined, the highest scores were attained when student-active lecture and laboratory activities were integrated in their presentation. Similarly, scores for traditional lecture and laboratory were the lowest; there was not a consistent difference between majors and non-majors courses. Students in traditional lecture courses combined with investigative laboratories obtained intermediate scores, and again there was not a consistent difference between majors and non-majors. Although similar tendencies are clear with each concept, the only statistically significant gain over the traditional approach was found in the category of improving scientific literacy.

Figure 3. Impact of teaching style on student learning (percent correct on content post-test) in four concept areas: Scientific Literacy, Variation, Heritability, and Natural Selection.

It is also clear from the data that some misconceptions are more ingrained than others. In particular, misconceptions concerning natural selection are particularly resistant to instructional intervention. Scores in this category were the lowest and showed the least change between pre-test and post-test scores. Scores in heritability, directly related to Mendelian genetics, consistently showed the greatest gains.

Figure 4. Data from current study superimposed on physics data reported by Hake (2002) demonstrating efficacy of "interactive engagement" over traditional lecture/laboratory. Three large "stars" represent experimental course from present study. Two large solid circles represent the TWO BEST sections of traditional control courses.

The results of this study are comparable to similar results in physics, which demonstrate that students taught by interactive engagement consistently outperform students taught by traditional lecture and laboratory (Hake 2002). Hake’s report summarized results from 62 physics courses enrolling more than 6500 students and different grade levels and from around the country. I have plotted data from the present study on top of Hake’s physics data (Figure 4). The three large stars represent the interactive/investigative sections from the present study and the two large circles represent the two highest performing sections of traditional lecture/investigative laboratory from this study.

Conclusion

It is well recognized that students bring to class many misconceptions concerning the nature of science and the nature of evolution. These beliefs, which often seem common sense and are reinforced by the media, are particularly resistant to modification — regardless of the pedagogy employed. This study provides some evidence to support the claim that student-active learning, where students are actively engaged in problem-solving, is more effective than traditional instruction in overcoming this barrier. Although with only one exception the data reported are not statistically significant, the consistency of the trends suggest that the observed differences are due to more than sampling error or chance.

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About the Author(s): 
Marshall D Sundberg
Department of Biological Sciences
Emporia State University
Emporia KS 66801
sundberm@esumail.emporia.edu