to the State Board of Education of Texas
Steven D. Schafersman
Texas Citizens for Science
August 18, 2003
My written testimony consists of four parts:
1. A general analysis of the science textbook adoption process in Texas by the State Board of Education.
2. Answers to the written testimony of the Discovery Institute and other questions members of the SBOE asked me about evolution and the methods of science.
3. A detailed scientific review and exposé of the new "Texans for Better Science Education" advocacy website by creationist Mark Ramsey of the Greater Houston Creation Association.
4. A copy of "Icons of Evolution?" by vertebrate paleontologist Alan Gishlick of the National Center for Science Education, which is the most detailed scientific review and refutation of the pseudoscientific book Icons of Evolution by creationist Jonathan Wells of the Discovery Institute.
Part 1. Science Textbook Adoption in Texas
The wisest and most responsible strategy of centralized state textbook adoption is to simply adopt textbooks written by experts in their field. In the case of science textbooks, this means books written by scientists and science educators are the most reliable and acceptable. It is, of course, entirely appropriate that a state that has a centralized adoption process--and the considerable resources necessary to perform the tasks--that the textbooks be examined (1) for errors of fact by independent science experts, (2) to ensure that they meet the state science curriculum requirements (in Texas, the TEKS, Texas Essentials of Knowledge and Skills), and (3) to ensure that they contain content about scientific information, theories, and controversies when appropriate that encourages critical thinking by students. Most importantly, by law the SBOE must adopt every textbook submitted that meets these requirements (and a fourth requirement--possessing a sturdy binding--that will not be considered here).
The reason for the first task is because school textbooks, including science textbooks, are written by scientists, science educators, and often non-scientist editors who are not experts about every topic in a discipline, and the textbooks often do contain factual errors. In my 22 years of teaching college science courses and reviewing high school science textbooks, I have found dozens of errors in both high school and college science textbooks. You might think these errors would be eliminated over successive editions as textbooks are repeatedly reviewed by independent editors and rewritten by authors, but surprisingly they are not, and new errors inevitably creep in. The number of errors and the quality of the scientific content varies among publishers and authors, so this is a legitimate matter of concern to centralized adopters (indeed, it is a matter of concern to independent school districts across the country that adopt textbooks locally and individually). So I heartily endorse the process of having expert science textbook panels review the textbooks for factual errors.
The Texas Education Code, §31.023, requires that textbooks be "free from factual errors." The Texas adoption process does thankfully check for factual errors and the members of the SBOE have the proper power to reject textbooks that contain factual errors or--as is usually the case--allow the publishers to correct errors brought to their attention to permit adoption. The concern (for potential abuse of the process) here is that an alleged "factual error" actually be a true error, and not a scientific or historical fact that a SBOE member disagrees with for political, religious, or ideological reasons and wishes to term an "error." Whether a statement is a factual error or not must be ascertained by the testimony of presumed experts; in Texas, this expert testimony would include that of the Texas Education Agency science staff, the scientist and science educator members of the appointed science textbook review panels, and the scientist and science educator witnesses who testify at SBOE hearings. It is irresponsible and unwise for SBOE members to substitute their own fallible and uninformed opinions about science facts for those of recognized and trained specialists in the scientific disciplines. I urge the SBOE members not to do this.
The reason for the second task is also obvious: textbooks should cover the topics required by a state's curriculum requirements. For the purposes of this analysis, I will stipulate that the TEKS is a satisfactory state science curriculum standard. Textbooks that cover all the TEKS are put on a conforming list of acceptable books, while those that cover at least half but not all of the TEKS are put on a nonconforming list. School districts overwhelmingly adopt textbooks from the conforming list. I have been told that textbooks on the nonconforming list--that could contain 99.99% of the TEKS requirements--are almost never adopted, and being put on the nonconforming list is equivalent to receiving a "kiss of death." The concern (for potential abuse of the process) here is that the SBOE will adopt biology textbooks but put them on the nonconforming list if they fail to include the bogus "weaknesses" about evolution that the Discovery Institute and some Board members are attempting to illegitimately force into the text. Publishers that agree to censor their textbooks will be placed on the conforming list of adopted books and thus will be purchased by the state in far greater amounts.
If this description of abuse of the process actually transpires, publishers with integrity--who refuse to censor their textbooks according to the political, religious, or ideological biases of SBOE members--will find their books placed on the nonconforming list (or on the rejected list), and will feel aggrieved and have a potentially actionable cause for litigation. If their biology books actually contain no factual errors, and this can be attested to scientist witnesses, then biology textbook publishers will have financial incentive to sue the SBOE if their books are not adopted because they failed to make the conforming list. The publisher of an environmental science textbook, Jones and Bartlett, last year found themselves in this position. Their book was illegally rejected by the SBOE because the publishers refused to make an inaccurate and unscientific change of a passage which said that "too many people reproducing too quickly" could be harmful to the environment. The market for environmental science textbooks in Texas is small, with no financial incentive for Jones and Bartlett to litigate. But the biology textbook market in Texas is worth hundreds of millions of dollars over the eight year adoption cycle, so publishers of biology textbooks may feel compelled to act differently if they find themselves in the same situation as publishers of environmental science books.
The reason for the third task is to ensure that textbooks are adopted that enable students to "analyze, review, and critique scientific explanations, including hypotheses and theories, as to their strengths and weaknesses using scientific evidence and information" (TEKS §112.43c(3)A). Every educator, including myself, is eager for students to master critical thinking skills, for such skills enable a student to analyze, investigate, reason, and reach reliable conclusions about important intellectual topics, for these educational abilities will be valuable for any person throughout life. Just below in this written testimony I will discuss the history and rationale of the (3)A requirement, the reason for its peculiar and rather unscientific wording, the fact that it is really unnecessary, and the problem that if it were to be rigorously enforced it would be pedagogically counterproductive.
But for now let me acknowledge and accept the TEKS §112.43c(3)A requirement, but point out that for this requirement to be met three factors are necessary: First, to be treated properly in textbooks, all "scientific explanations, including hypotheses and theories" must be presented in a fashion that enables students to "analyze, review, and critique . . . their strengths and weaknesses"; it is impermissible to focus on a single explanation or theory for both pedagogical and legal reasons. Second, since many scientific explanations do not have "weaknesses," problems, controversies, and disagreements, it is impermissible to fabricate bogus "weaknesses" to force into textbooks using requirement (3)A as a justification. Third, requirement (3)A explicitly says that the ability to analyze, review, and critique the strengths and weaknesses of scientific explanations be based on "scientific evidence and information" (emphasis added); it is impermissible to use non-scientific or pseudoscientific evidence, information, and arguments for this purpose.
As with the first two tasks, the concern (for potential abuse of the process) here is that some SBOE members will use TEKS (3)A as a justification to (1) focus only on the topic of evolution as the place to insert "weaknesses," (2) hold up the occurrence of evolution--as the natural process generating ancestral-descendant relationships among taxa--as an explanation to exhibit fabricated, bogus "weaknesses" when in fact it has none (this explanation is completely accepted by all biologists), and (3) use pseudoscientific arguments and evidence from the Discovery Institute to create "weaknesses" to cast doubt on both the occurrence and theory of evolution.
The rationale for factual and error-free science textbooks and for textbooks that treat the totality of a state's science curriculum requirements is beyond dispute. However, Texas has a third requirement that is more unusual. This is TEKS §112.43(c)(3)A, which fully stated is as follows:The student uses critical thinking and scientific problem solving to make informed decisions. The student is expected to analyze, review, and critique scientific explanations, including hypotheses and theories, as to their strengths and weaknesses using scientific evidence and information.
I promised to explain the history and rationale of the (3)A requirement, the reason for its peculiar and rather unscientific wording, the fact that it is scientifically unnecessary in any K-12 educational setting, and the problem that if it were to be rigorously enforced it would be pedagogically counterproductive. Let's turn to this now.
TEKS (3)A was added to the newly created TEKS curriculum adopted for 1998, but the phrase existed in earlier state curricula. Throughout the 1970's and early 1980's, an earlier SBOE had a textbook rule that mandated that an anti-evolution disclaimer be placed inside the front cover of every biology textbook. Two organizations, People for the American Way and the Texas Council for Science Education (my earlier organization) fought against this rule throughout 1983-1984. We succeeded in 1984 when Texas Attorney General Jim Mattox ruled that the disclaimer rule was a violation of the Constitution and must be removed. The removal of this egregious and scientifically-mendacious rule was the ultimate impetus for the new rule now known as TEKS (3)A. This rule was deliberately adopted by the SBOE to deal with the topic of evolution in biology textbooks in Texas, because unlike most states, ours has a high number of religious fundamentalists who object to teaching evolution to students and who frequently find themselves elected to the State Board of Education.
The rule was written by Board Member Will Davis, who thought it would end the continuing and acrimonious debate that occurred every time biology textbooks were adopted. I vividly remember discussing this phrase with Mr. Davis sometime in the mid to late 1980's when it was proposed for adoption: I objected to its potential adoption, saying that creationists would try to use the phrase to sneak unscientific, anti-evolution content into the books using the requirement as a spurious justification. I also used some of the arguments I repeat below. Mr. Davis replied that the requirement was adopted specifically to placate creationist critics and it was needed to move ahead with biology textbook adoption. He also replied by saying that the requirement specifically refers to "scientific evidence and information," and that if there is no such scientific evidence against evolution, then creationists would not be able to insert this material, and it would be mine and other scientists' responsibility to make sure this didn't happen.
Another important fact surrounding TEKS (3)A is that since it is illegal for a state government body to adopt any rule that focuses squarely on the topic of evolution (federal courts have ruled that this constitutes establishment of religion), so any rule must be adopted as a general application to all scientific inquiry, one that does not single out for its requirements any single theory or topic of one scientific field (such as evolution in biology). Thus, the (3)A rule is also found in the TEKS textbook requirements for high school physics, chemistry, environmental systems, integrated physics and chemistry, aquatic science, astronomy, and geology, meteorology, and oceanography, as well as biology. This is both appropriate and legal for any rule that requires specific content, but it places the additional burden on those who wish to invoke the rule in biology textbooks that they must do precisely the same for every other science textbook used in Texas. If the SBOE only invokes or enforces the rule for the topic of evolution in biology textbooks, this practice is as illegal as writing the rule only for evolution in biology textbooks. I only point out that the present SBOE is thus acting illegally (violating the Establishment Clause of the First Amendment to the Constitution) by focusing solely on evolution, and this fact will be an issue in any future litigation.
Now we are at a juncture when we must squarely face the implications of TEKS (3)A. The rule is certainly going to be used by creationists on the SBOE to justify inserting scientifically misleading and unwarranted content about evolution into biology textbooks by claiming that the rule requires that scientific "weaknesses" and well as "strengths" be covered for hypotheses and theories. And if such "weaknesses" are not included, the SBOE will place the offending books on the nonconforming list and consign them to marketing hell. For example, SBOE member Teri Leo (SBOE textbook adoption public hearing, July 9, 2003) has stated the following:There are those today that would censor out all credible science that opposes Darwinian evolution. By presenting scientific controversy realistically, students will learn how to evaluate competing interpretations in light of evidence. However, books reviewed to this day, in my opinion, do not include scientific weaknesses to the biologic theory of evolution. Hence, if no changes are made to the textbooks, the rules of this Board say they must be rejected as nonconforming until such scientific weaknesses can be incorporated into the texts.
In addition, SBOE member Don McLeroy (SBOE textbook adoption public hearing, July 9, 2003) stated the following:Unfortunately, the TEA review panel have certified the books as conforming if just some theories and hypotheses had just some strengths and weaknesses mentioned in the book. This is not the correct interpretation. TEKS 3A requires each and every hypothesis and theory. And each of those must have strengths and weaknesses covered. . . . During a discussion on whether to place a book on the nonconforming list for its failure to present weaknesses of evolution, the minutes record . . . that the State Board of Education expects strengths and weaknesses to be included in books. . . . Since the TEA did not correctly direct the review panels in their proper responsibilities, the Board should not accept the review panels' findings on the biology books. [T]his leaves the responsibility to the State Board of Education, [which] has authority to determine whether the material is sufficient to address the TEKS.
There is no question that TEKS (3)A is going to be the primary means used by creationists to try to debilitate the coverage of evolution and the origin of life in biology textbooks by attempting to insert "weaknesses" about evolution into them. This action would debilitate, dumb-down, and weaken the scientific coverage of evolution in biology textbooks, ensuring that students would receive a third-rate science education in Texas. The reasons inserting "weaknesses" would damage science education and not--as alleged by anti-evolutionist critics--improve critical thinking are complex but not mysterious. I will list them all here and then summarize them collectively and briefly:
1. "Weaknesses" is not a term that scientists usually use to describe scientific explanations, hypotheses, and theories. Rather, scientists speak of problems, controversies, disagreements, criticisms, knowledge gaps, and even mysteries. A scientist might casually characterize another scientist's explanation or hypothesis as having "weaknesses," but this would rarely be stated formally in a science book or journal.
2. The idea of "strengths and weaknesses" of "scientific hypotheses and theories" is misleading. Hypotheses are tentative explanations that must be tested; their outstanding weakness is that they have not been corroborated or confirmed. Once tested and corroborated, the explanations become reliable knowledge and are no longer hypothetical. They are incorporated into theories which themselves are extremely reliable and have few or no weaknesses (only gaps in knowledge). About the only real hypotheses that one might encounter in an introductory biology book are different hypotheses about the origin of life (there are four or five major ones and about a dozen minor ones).
3. Introductory science textbooks rarely contain hypotheses; they almost always only contain reliable knowledge in the form of what would popularly be termed facts, and this includes theories, which are as reliable and factual as anything humans know. Often these books would also discuss gaps in knowledge, unsolved scientific problems, and social controversies involving scientific information, but never "weaknesses" of hypotheses and theories. No doubt knowledge in science is theoretical, and this knowledge started out as hypotheses, but now most of scientific knowledge would be properly termed "reliable knowledge." It is this information--reliable knowledge--that fills introductory science textbooks, and while this information is subject to analysis, review, and understanding, it is not really subject to "critique" by K-12 students.
4. Scientific theories are too massive and established to expect any high school student to critique or question. The vast majority of high school students would not be able to perform such critiques in a scientific way. Scientific theories should be accepted as reliable knowledge in K-12 classes, and not made the object of questioning until they have the educational training necessary to do so, which consists of years of graduate study at universities.
5. Scientific problems, controversies, disagreements, criticisms, knowledge gaps, and mysteries certainly exist, but they exist at the frontiers of scientific research for which advanced scientific knowledge and experience are required to understand and deal with them.
6. Real scientific problems, controversies, etc., should not be included in introductory science textbooks, because they are almost always too difficult to understand and their presence would only lead to student confusion and frustration. Such confusion and frustration in science class actually prevents students from learning critical thinking, not helps them to learn it.
7. Introductory science textbooks are written to be used by introductory science students who do not have the technical and conceptual background to understand the complex issues involved. High school textbooks are intentionally simplified by design; students who become interested in science can learn about the complexities, problems, and controversies in college, and can also begin dealing with them there.
8. There are no scientifically-legitimate "weaknesses" about the occurrence of evolution by natural selection--defined as the descent of all living and fossil species of organisms from a common ancestor through time by natural selection acting upon the gene pools of species populations--evolution is as confirmed, reliable, and accepted as anything in science and can be considered to be a fact. Hypotheses about the origin of life, however, all have uncertainties and missing pieces, but I know of no textbook that only presents one solution to the origin-of-life problem.
9. There are certainly problems, controversies, difficulties, and knowledge gaps with the modern theory of evolution--the explanation of how the mechanism of the evolutionary process operates over time--but for the reasons stated above, these topics are just too complex to be dealt with in high school. They almost never are, and the textbooks need not and usually do not cover them. The same is true for all other scientific theories in all disciplines. It takes a lifetime of training and study to deal with only a few problems in one science. Trying to cover them all in all sciences at the high school level is impossible.
10. It is quite true that learning critical thinking skills--an essential educational goal--requires a student to be able to analyze, review, and critique evidence and reasoning used to support simple experimental hypotheses and other elementary knowledge claims. Such critical thinking activities are something students should definitely be doing by the time they are in high school. But the place for this in high school is in the laboratory, where students deal with simple experiments, simple observations, simple hypotheses, and simple tests. Student hypotheses are the proper place to deal with "strengths and weaknesses," and "analyze, review, and critique scientific explanations."
11. Another opportunity to learn critical thinking skills in science class is when the teacher discusses social issues concerning science with students. Many of these social issues--such as embryonic stem cells, human cloning, genetically-modified foods, environmental pollution issues, biodiversity loss, excessive human population growth, etc.--are properly covered in science classes, are controversial and have difficult solutions, and require critical thinking skills and reasoned judgment to "analyze, review, and critique."
12. It should thus be clear by now that the concept of mandatory instruction of students about "strengths and weaknesses" of "scientific hypotheses and theories" is not really good scientific language, and the reason the phrase is used is because the (3)A rule was written and adopted by non-scientists--without proper scientific input--precisely to placate an obnoxious creationist minority. A scientist would have phrased the (3)A rule as follows: "The student uses critical thinking and scientific problem solving to make informed decisions. The student is expected to understand why scientific explanations are so reliable, and be able to analyze, review, and critique experimental results in the laboratory and social uses of scientific data in the classroom as to their strengths and weaknesses using reliable scientific evidence and information."
13. The inordinate concentration by creationist critics on the topics of evolution and origin of life in only biology textbooks, rather than on the many other topics in all disciplines of modern science, reveals that their true intention is to weaken all biology textbooks' accurate coverage of these topics alone, thus perverting evolution's important place in modern biological understanding. There is no legitimate reason to focus on only one scientific topic to insert "weaknesses." Such an obsession can only have an ideological or religious motivation, not one to improve science education, and if adopted as formal state rules is illegal as well, since it constitutes an establishment of religion.
14. Anti-evolutionist creationists are sincerely not attempting to remove evolution from the curriculum, force creationism or intelligent design into the curriculum, or ask for equal time for their pseudoscience to be taught with science. The reason is simple: these things are all illegal. Creationists and anti-evolutionists certainly wish they could do these things, and they have certainly attempted to do them many times in the past, but they have always failed because the courts recognized that their efforts constituted an establishment of religion. Today, rather, they attempt to discourage the teaching of evolution by making the topic controversial in textbooks and thus in the minds of teachers. Their goal today is to discourage and intimidate teachers into avoiding or shortchanging the topic of evolution in the biology classroom, so as to censor the topic of evolution from every students' scientific education, and deprive them of a modern appreciation of science and the scientific method--which is identical to critical thinking.
15. Anti-evolutionist creationists use marketing techniques, argumentative persuasion, and political lobbying and intimidation, not the methods of science to achieve their goals. They go from state to state (Kansas, Ohio, Texas) trying to push their anti-evolution ideology into state curriculum standards and textbook adoption processes. In every state, the legitimate scientists and science educators have opposed them (and ultimately winning in Kansas and Ohio). The fundamental fact is this: If creationist anti-evolutionist critics really wanted to improve science education, they would leave the science curriculum standards and science textbook content to the scientists, science educators, and science specialists who have been responsible for these in the past, and not attempt to use the political process to force scientifically illegitimate and unwarranted changes into the educational materials.
Let's summarize all these arguments briefly. It is both unwise and irresponsible for a politically elected body of officials, the State Board of Education, to insert unscientific content into science textbooks over the objections of their own science staff, their own science textbook review panels, and the scientists and science educators who testified against it. This would be a gross abuse of the regulatory process, and would be illegal and costly enough to invite litigation from textbook publishers. Such action--motivated solely by ideological, political, or religious reasons--is exactly similar in intent (but fortunately not in scale) to the substitution of the science of genetics in the Soviet Union with the incompetent Communist pseudoscience of Lysenkoism, and the substitution of scientific anthropology in Germany with the murderous Nazi pseudoscience of eugenic Aryanism. Both were mandated by the controlling political party in each country at the time, and each pseudoscience resulted in, respectively, the death by starvation of millions of humans and the death by murder of million of humans. Today in Texas, the controlling political party seems hell-bent on repeating these historical tragedies, albeit at a smaller scale. While no doubt present-day ideological believers on the Texas SBOE wish to duplicate the fervor, passion, and stubbornness of historical believers, there is no reason for them to emulate their historical dogmatism, ignorance, and bigotry, especially when the victims of the resulting abuse would be millions of school children of Texas, who really need to understand critical thinking and the modern scientific view of the world in order to be good citizens and productive workers in society.
Forcibly inserting unscientific "criticisms" and "weaknesses" of evolution into biology textbooks would not improve critical thinking, but destroy it by misleading and confusing students, intimidating teachers to avoid or weaken the subject, and teaching students a perverted view of science. As I explained above, there are few or no hypotheses in introductory biology textbooks; instead, the books are filled with reliable scientific knowledge, including scientific theories, that in general have no "weaknesses." Scientific theories can indeed be criticized, because they are incomplete, but such criticism can only be competently understood and conducted in graduate schools and research universities, not in high schools using introductory textbooks. The concept of students learning about the "strengths and weaknesses" in scientific "hypotheses and theories" in high school is unscientific and pedagogically useless.
The proper meaning of having students learn "critical thinking and scientific problem solving to make informed decisions [by being] expected to analyze, review, and critique scientific explanations . . . as to their strengths and weaknesses using scientific evidence and information" should not be directed at hypotheses and theories (as the (TEKS (3)A) rule unfortunately and misleadingly states), but to laboratory experiments and classroom discussion about topics involving scientific knowledge, social practices, and decisions by public officials. Modern scientific explanations, including theories, should be accepted as reliable knowledge by high school students and teachers without the obfuscation of forcing fallacious "weaknesses" into them.
Finally, as I will show below, the "weaknesses" and "criticisms" of the theory of evolution put forward by the Discovery Institute critics are in reality bogus; the "weaknesses" don't in fact exist. The DI's written testimony to prove the contrary is misguided, illogical, and lacks empirical validity. This alone should warn SBOE members and the public that something fishy is going on: an out-of-state think-tank--whose stated purpose is to change public opinion by lobbying and marketing techniques, not by traditional scientific methods--comes into Texas and finds friendly and sympathetic co-believers on the State Board of Education. The think-tank produces written testimony that claims that standard biology textbooks, successfully used for years throughout the United States, in fact fail to meet scientific standards of accuracy and critical analysis. Well, this is certainly news to hundreds of thousands of scientists and science teachers. Whom should one believe?
It is obvious that--despite the legislative reforms of 1995, and the Attorney General's 1996 opinion that the SBOE does not have the authority to adopt a rule to require specific content in textbooks beyond the statutory standards of meeting the curriculum standards, meeting the binding standards, and are free of factual errors--the potential remains for political abuse of the process of textbook selection in Texas. State Board members have the potential to act unwisely and irresponsibly in the adoption process by ignoring the TEA science education staff, science textbook review panel members, and scientist and science educator expert testimony, and then (1) claiming that a science textbook contains factual errors when it actually does not, (2) claiming that a textbook does not meet all the TEKS science curriculum requirements, including TEKS (3)A, and adopting it on the nonconforming list that condemns it to a marketing death, and (3) requiring that a publisher change (i.e. censor) its book to add bogus "weaknesses" that are not scientific or do not exist, or else reject the textbook. Not only does this potential political abuse of the adoption process exist, but the abuse has already manifested itself in 2002 during the adoption of environmental science books, and obviously every person who testified on behalf of keeping the biology textbooks free of censorship at the July 9 hearing expects it to happen again.
There are three independent ways to prevent future political abuse of the textbook adoption process in Texas:First, the majority of SBOE members could stop indulging their political, religious, and ideological prejudices in their management of textbook selection and start relying on the competence, knowledge, and integrity of science textbook authors, the TEA science education staff, and scientists and science educators who testify in public hearings and those on their own textbook review panels.
Second, the centralized, authoritarian textbook adoption process could be abandoned by either statute or litigation, and Texas could allow school districts to begin choosing their own textbooks directly from the publishers (as is the process in most of the states in this country) and paid for as part of the state funds given to all school districts on the basis of enrollment. Litigation--from aggrieved publishers or school districts--may very well be the impetus that ends the centralized, authoritarian, and thoroughly politically-pervaded Texas textbook adoption process; if so, I volunteer to be a witness for the plaintiffs.
Third, the Texas legislature could make the SBOE an appointed board again (qualified members would be appointed by the governor, as was the case for several years after the Ross Perot Committee reforms), thus eliminating the practice of stealth candidates running for the SBOE in order to promote their political, religious, and ideological views in the Texas public education system.
One of these three solutions to the problem will have to occur, or we will continue to see the perversion of public school science education in Texas, with the result that Texas students will continue to be ill-prepared to face the modern world with their censored and incompetent knowledge of science (as is revealed every year by Texas students scores on standardized national science exams). If such a shameful situation is allowed to continue, it will continue in an arena of national publicity, and a spotlight will be focused on those public officials who are responsible for its maintenance.
Part 2. Answers to Questions about Evolution
As I have emphasized before, anti-evolutionists and creationists attempt to persuade readers and listeners by using specious arguments, deliberate misrepresentation, quotes out of context, untruths and half-truths, and debating techniques to confuse and impress the victim. In general, these methods are disreputable and would never be indulged in by legitimate scientists or serious scholars. Creationist practices invariably involve pseudoscholarship in the service of pseudoscience, and polemics masquerading as analysis. One of these techniques is the argument from authority. Creationists love to claim that legitimate practicing scientists exist who support their views (creationism, intelligent design, weaknesses in the theory of evolution, etc.). For example, Dr. Francis Beckwith, Associate Director of the J. M. Dawson Institute of Church-State Studies at Baylor University said the following (SBOE textbook adoption public hearing, July 9, 2003):These textbooks [should] appropriately convey to students some of the critical questions raised about aspects of evolutionary theory in general and neo-Darwinism in particular. These questions have been raised by scholars who have had their works published by prestigious presses, academic journals, have aired their views among critics in the corridors of major universities and other institutions and have been recognized by leading periodicals both academic and non-academic. They are affiliated with a number of institutions, including the University of Texas, Texas A&M and Baylor.
But the truth is quite different. These "scholars" are not biologists and not even scientists; for the most part, they are individuals trained in philosophy, mathematics, engineering, and even the sciences, but who are not actually working in science. Some legitimate philosophical journals and academic presses will publish there writings, and there is nothing wrong with this. I agree that intelligent design, for example, is a legitimate philosophical topic that has a place in academic or intellectual discourse. But these topics are not studied by real scientists, nor do real science journals publish papers about these topics (except book reviews that have universally been highly critical). These "scholars" do exist in the philosophy department at the University of Texas at Austin, the engineering department of Texas A&M, and in a number of institutes and programs at Baylor University, but I can positively state that there is no scientist in the biology departments of any of these universities who would agree with the anti-evolutionist critics represented by the Discovery Institute, and none who would approve of politically inserting "weaknesses" about evolution into introductory biology textbooks without prior scientific justification by standard biological methods. Indeed, every legitimate scientist and science educator who testified on July 9 did, or who will testify on September 10 will, disagree with both the goals and tactics of the Discovery Institute representatives; all did and will object to efforts by elected SBOE members to bypass normal scientific practice and insert unwarranted items into science textbooks by regulatory fiat.
No individual representing the Discovery Institute-Center for Science & Culture is a legitimate scientist. I agree that some of the DI representatives have received scientific training, including Michael Behe, Jonathan Wells, Stephen Meyer, Paul Nelson, and William Dembski; all are certainly knowledgeable about science and all have doctorates, but these individuals are not scientists because they do not behave like scientists. The reasons are simple: real, legitimate scientists accept the practice of methodological naturalism in scientific method, eschewing the supernatural in science; they perform experiments and make observations to answer question and solve problems within a common theoretical framework accepted by the scientific community; if they disagree with the common theoretical framework, they are obligated to produce genuine evidence and logical reasons that casts doubt on modern theory; they publish their scientific work in peer-reviewed science journals, saving educational, historical, cultural, and philosophical material for books; they take to heart the cogent criticisms by their colleagues and make corrections, not obstinately refuse to change a word and instead make up ad hoc arguments to save appearances; they do not indulge in pseudoscholarship: specious arguments, sophistry, illogical reasoning, hidden false premises, assumed presuppositions that have no basis in fact, deliberate misrepresentation and misunderstanding, quotes out of context, quotation mongering and credential peddling, etc.; they do not attempt to use raw political power to authoritatively accomplish educational goals that they cannot legitimately accomplish using reasoned discourse, responsible inquiry, and scientific persuasion. The Discovery Institute associates fail all of these tests, thus clearly revealing themselves to be pseudoscientists, not scientists.
No one seriously recognizes Drs. Wells, Dembski, Meyer, or Nelson as legitimate, practicing scientists; they would be charitably characterized as scholars, philosophers, polemicists, and popularizers. I would additionally characterize them as creationists and pseudoscientists, but they would no doubt object to those labels. But what about Michael Behe, who is a tenured biology professor at Lehigh University in Pennsylvania. I fully agree that his scientific work conducted prior to earning tenure at Lehigh was legitimate science, and he was a real scientist then. But now his "research" focuses on intelligent design, which is a philosophical, pseudoscientific program (but there is little his university can do about that; for many years, a famous psychology professor at Harvard has been conducting research into the extraterrestrial alien abduction of humans, something which he devoutly believes occurs; his colleagues tried to get rid of him, but tenure ultimately prevented them). In addition, Professor Behe has engaged in many debates with legitimate scientists in the popular philosophical literature and on the Web, and he has refused to change any of the illogical arguments he uses to reason to his conclusion. His book, for instance, Darwin's Black Box, is one long argument from ignorance, which has been pointed out by dozens of scientist reviewers, including myself, but he obstinately refuses to acknowledge this. This is not the mark of a true scientist. Michael Behe's book has received universal criticism and condemnation from the scientific community; for dozens of negative reviews and criticisms by scientists, please visit Behe's Empty Box at <http://www.world-of-dawkins.com/Catalano/box/behe.htm>.
Dr. Michael Behe is a Senior Fellow of the Discovery Institute-Center for Science & Culture. He actually accepts quite a bit of modern evolutionary theory, but he insists--contrary to all evidence--that an intelligent designer was necessary to get the evolutionary process going early in Earth's history by somehow creating the first "irreducible complexity" in nature. He and his other DI associates identify this intelligent designer with the Christian God, but he claims this is irrelevant for a scientific understanding. Well, that's nonsense; the identity and characteristics of any presumed intelligent designer would have to be susceptible to empirical study by other scientists, but this can't be done when dealing with the supernatural. Many scientists, including myself, have published reviews of his writings that demonstrate that his concept of irreducible complexity of structures and processes is wrong, and criticize him for his refusal to explain how the intelligent designer actually created the first complex organism. But Behe continues to indulge in ad hoc arguments to maintain his beliefs. This is not the mark of a true scientist.
Discovery Institute Written Testimony
The Discovery Institute written testimony, "A Preliminary Analysis of the Treatment of Evolution in Biology Textbooks currently being considered for adoption by the Texas State Board of Education," is a warmed-over version of a book by Discovery Institute-Center for Science & Culture Senior Fellow Jonathan Wells, Icons of Evolution, in which Dr. Wells tries to convince the reader--using the entire armamentarium of pseudoscientific pseudoscholarship--that the standard or classical textbook arguments and illustrations of evolution (the "icons") are variously misguided, misrepresentative, and false. His book has received universal criticism and condemnation from the scientific community. Links to most of these critical reviews can be found on the Texas Citizens for Science Hearing Page at <http://www.txscience.org/hearing.php>. Both the "Preliminary Analysis" and Icons of Evolution can be summarized as follows: they are filled with fallacious arguments, distortions, untruths, specious reasoning, and have a deceptive and mendacious attitude that is clearly observed by anyone possessing a scientific understanding of modern evolutionary theory and the evidence for it. It is practically beggars belief that any educated person would be persuaded by the arguments in these two publications, but experience has proven that humans are deceived again and again, because sophistry by definition is meant to be convincing to readers and listeners who are unprepared to respond to specious arguments. And pseudoscientists are masters of sophistry.
The Discovery Institute-Center for Science & Culture itself has the goal of "nothing less than the overthrow of materialism and its cultural legacies. Bringing together leading scholars from the natural sciences and those from the humanities and social sciences, the Center explores how new developments in biology, physics and cognitive science raise serious doubts about scientific materialism and have re-opened the case for a broadly theistic understanding of nature." The DI-CSC proposes "a positive scientific alternative to materialistic scientific theories, which has come to be called the theory of intelligent design (ID). Design theory promises to reverse the stifling dominance of the materialist worldview, and to replace it with a science consonant with Christian and theistic convictions" (www.txscience.org/files/wedge.htm). Any reader, therefore, can clearly see that the Discovery Institute associates do not have an unbiased view of evolution and the rest of modern science, and do not have the best interests of Texas students at heart. Jonathan Wells, for instance, studied to obtain a Ph.D. in biology only so he could "devote my life to destroying Darwinism" (http://www.tparents.org/library/unification/talks/wells/DARWIN.htm). The fact that "Darwinism"--what real scientists call the theory of evolution by natural selection--is universally accepted by the world's biological scientists, and is vital for every educated person to learn so that he or she can understand modern biological principles and processes, is seemingly irrelevant to Dr. Wells.
I am going to review the DI "Preliminary Analysis" (hereafter PA) below. Frankly, I have neither the time nor desire to review it in detail, with scientific citations and references, since this has already been done by Dr. Alan Gishlick in "Icons of Evolution? Why much of what Jonathan Wells writes about evolution is wrong," his outstanding review of Wells' book Icons of Evolution, which, as I said above, is the entire source of the PA. So I am going to review the PA superficially by simply quoting passages from it that distort the truth, responding with the correct scientific information, and allowing interested readers to refer to Dr. Gishlick's review for all details, citations, and references. To aid this process, I am including a complete copy of Gishlick's review in this testimony, but am omitting the many figures his review contains but which are available at its original source of <www.ncseweb.org/icons/>. Dr. Gishlick will be present at the September 10 hearing, so SBOE members will be able to personally ask him questions if desired.
The Miller-Urey Experiment
The Miller-Urey experiment is an excellent illustration of how modern science works. It is used in introductory biology books to illustrate how organic compounds that are necessary for life can be formed on Earth by nonbiologic chemical reactions. The original gas mixture that Miller used was later determined to be highly improbably, but subsequent experiments with other gas mixtures have achieved similar results. It is best to use Miller's experiment as an historical demonstration and mention that subsequent experiments by others have demonstrated the same results. (NOTE: All PA quotes will be indented in what follows.)Yet textbooks continue to feature the experiment, complete with photographs or drawings of Miller's original apparatus, as evidence that life's building blocks could have formed spontaneously on the early Earth.
There is nothing wrong with this. The photographs or drawings can be used for historical reasons. Life's building blocks did indeed form spontaneously on the early Earth and in the early solar nebula and solar system.Many textbook accounts of the Miller-Urey experiment fail to inform students that the Earth's early atmosphere was probably quite different from the mixture of gases used in the experiment, or that when the experiment is repeated with a realistic mixture it does not work.
All textbooks should inform students that the mixture of gases that Miller used was different than what scientists now suspect constituted Earth's early atmosphere. Experiments repeated with a more realistic mixture do work to produce organic components of life: peptides, amino acids, etc. These compounds are also found in comets and meteorites that indicates they formed early in the solar system by nonbiological photochemical reactions.Even textbooks that hint at problems with the 1953 experiment typically tell students that more realistic gas mixtures still produce "organic molecules," without informing students that those molecules include toxic chemicals such as cyanide and formaldehyde but do not include amino acids.
Cyanide and formaldehyde are toxic only in concentrated form. In dilute and diffuse form--their characteristic form in nature--they are essential building blocks of life. Cyanide and formaldehyde, and many other organic compounds, are found in interplanetary and interstellar space, comets, and meteorites, indicating they can be formed by nonbiologic chemical processes occurring early in solar system formation.The truth is that scientists are as far as ever from understanding how life's building blocks formed on the early Earth, and even farther from understanding how cells formed from such building blocks.
False. Scientists have much greater knowledge today about how life and cells may have formed in the past. Dozens of contemporary books exist that detail this knowledge.Yet instead of informing students that the origin of life remains an impenetrable mystery, most biology textbooks give students the false impression that scientists have made great strides in understanding it.
The origin of life is certainly still a mystery, but it is not an impenetrable one, as creationists like to believe. Unlike creationists, scientists don't just give up and say "God did it." Instead, scientists are making great strides in solving the problems and understanding the process.Since they misrepresent the significance of the now-discounted Miller-Urey experiment, and mislead students about current state of origin-of-life research, such textbooks cannot enable students to "analyze, review, and critique scientific explanations, including hypotheses and theories, as to their strengths and weaknesses using scientific evidence and information"
The Miller-Urey experiment has never been discounted, only revised and repeated with different initial gas mixtures. The textbooks do not mislead students about the current state of origin of life research: the research is substantial, ongoing, and productive. A textbook either presents what information is reliably known about the origin of life problem and avoids going into detail about hypothetical solutions, or it presents alternative hypotheses (organic soup, geothermal vent, origin from clay, cometary source of vital ingredients, etc.) that can be analyzed and critiqued. Either solution is satisfactory. What would not be satisfactory is to censor the vital information that all scientists believe that life began on Earth by a natural process involving abiotic chemical reactions using organic compounds that formed spontaneously on Earth and in outer space, and that modern research has given scientists many tantalizing clues about how this process occurred, but much work remains to be done. This is really a very inspiring topic, because the tools to do significant research in this area didn't even exist twenty years ago.
Darwin's Tree of Life and the Cambrian Explosion
The "Tree of Life" is a fact acknowledged by all biologists and biology textbooks. There is even an extensive website that presents and explains this tree of life in exquisite detail (www.tolweb.org). The tree of life is merely all the taxa that live now or have lived in the past arranged on a tree-like diagram that illustrates their pattern of evolutionary descent. Determining the tree-like pattern using special software tools and character data of all taxa is a major biologic research project that will help us understand the evolutionary process much better.
The figure on the next page, "Levels of detail in genetic history: From individuals to the phylogenetic tree," illustrates how biologists envision genetic continuity from individual organism to species population to species lineage to ultimately a higher-taxa phylogenetic tree--the tree of life. There is no break in genetic continuity throughout evolution for some intelligent designer to miraculously insert complexity. The important point of this figure is to illustrate that every living organism, including every human, share a common ancestor with all other living organisms. This is the most important message that biology can teach, and it should be repeatedly emphasized in every biology textbook.
This is one of the PA's oddest criticisms of the biology textbooks. This topic is peripheral to most biology books, even at the university level; it is not treated by many of them, since it is an advanced topic. But the DI critics fault the books mostly for not covering this topic in the way that the creationists wish. The PA deliberately misrepresents the most basic principle of evolutionary descent, that when taxa appear on Earth their taxonomic rank can increase over time. That is, when a new species first evolves, it is just a species, but it can--through time and contingent evolution--give rise to many more species so that its hierarchical rank in the tree increases and we would begin classifying it as a genus. This process can continue, so that what was once only a new species can ultimately give rise to a new genus, family, order, class, and phylum many millions of years later. Remember, humans assign these taxonomic ranks after the fact; they are not assigned to taxa when they first appear on Earth and then have to keep them forever!
(Figure from Maddison and Maddison, 1999, "MacClade: Analysis of Phylogeny and Character Evolution")
Most major phyla first appear in the fossil record about 520-550 million years ago, in the Cambrian Period. The fossil record is spotty and incomplete, so the ancestors of the first organisms of these phyla found as fossils are not known. The geologically rapid appearance of all these phyla for the first time is termed the Cambrian Explosion; however, these taxa appeared during a 30 million year interval, so their evolution could be gradual in normal time, since their common ancestors presumably lived 20-50 million years before them, in the Precambrian. The figure below, from Conway Morris, 2000, (http://www.pnas.org/cgi/reprint/97/9/4426.pdf), illustrates this.
Principal events across the Vendian-Cambrian boundary, spanning an interval
of approximately 60 million years (570-510 Myr) (from Conway-Morris, 2000)
However, some scientists debate the sufficiency of microevolutionary processes (see below), the speed of evolution, the adequacy of the fossil record, and the nature of the fossils themselves to explain this rapid appearance. Many paleontologists don't consider the Cambrian Explosion a mystery, since evolution can proceed rapidly. Let's now examine quotes from the Discovery Institute PA on this topic.In the fossil record, however, most of the major phyla appear fully formed at the beginning of the geological period known as the Cambrian, with no fossil evidence that they branched off from a common ancestor.
This passage is deliberately and indeed maliciously misleading. There are many reasons why fossil evidence of earlier ancestors is absent: soft body parts, rapid evolution, poor stratigraphic record, bad luck for paleontologists, etc. But by no means does this imply that there is a question that the major phyla forms didn't have a common ancestor. Of course they did! Unless one is hypothesizing that there was a break in genetic continuity and a supernatural intelligent designer just stepped in with a miracle to create those forms we see.Darwin feared that the fossil record might by its very nature be so incomplete that a solution to the problem would never be found; but he hoped that future fossil-collecting might provide at least some evidence that animals shared a common ancestor. A century and a half later, however, the problem is more serious than ever.
False. We have many more fossils today and a much better understanding of the sequence of appearance of the different fossils and their timing. Darwin never doubted that animals shared a common ancestor. Darwin did indeed express concern that the fossil record was unavoidably incomplete, but he never doubted that a solution to the problem would never be found. The problem can in fact be solved without any fossil record: a detailed phylogenetic analysis would work if sufficient data were available. The occurrence of fossils just makes this task easier.A century and a half later, however, the problem is more serious than ever. Paleontologists once thought that Precambrian animals might have been too small to be detected, but microscopic single-celled fossils much older than the Cambrian have since been discovered. Paleontologists also used to think that Precambrian animals might not have fossilized because they were soft-bodied, but it is now clear that most of the fossilized animals in the Cambrian explosion were soft-bodied.
Once again, this presentation is extremely deceptive and misleading (it was always a question whether this is deliberate or due to simple ignorance; in the past, with ICR young-Earth type creationists, one was never sure; but today, the ID creationists receive much better scientific training, so I can only conclude that the deception is deliberate and mendacious). The fact that microscopic Precambrian fossils have been found does not guarantee that the ancestors of the Cambrian phyla must be found. They would be soft-bodied and preservation of soft-bodied organisms is extremely rare. Most of the fossilized animals in the Cambrian Explosion were not soft-bodied, but we are fortunate to have so many preserved under exceptional circumstances. There are only two really good examples of soft-body Cambrian preservation: one in China and a later one in Canada. Paleontologists still attribute the rarity of earlier fossils to the fact that they would not likely be fossilized because they were soft-bodied or because they evolved quickly in an environment that did not readily support fossilization.There is no excuse for a biology textbook to deal with the fossil record without even mentioning the Cambrian explosion. Furthermore, any biology textbook that fails to discuss the challenge posed by the Cambrian explosion to Darwin's theory would not enable students to "analyze, review, and critique scientific explanations, including hypotheses and theories, as to their strengths and weaknesses using scientific evidence and information."
Introductory biology textbooks do not need to mention the Cambrian Explosion, but it would certainly be okay if they do. In fact, I would recommend to authors and publishers that all begin to cover this topic; it would be exciting for students to see pictures of the weird and wonderful fossils found 520-550 million years ago, and give them an introduction to ancient time. In either case, the Cambrian Explosion does not provide a challenge to modern evolutionary theory. Many aspects of evolutionary theory exist that can explain what we observe. The challenge is to identify the correct evolutionary processes and sequence of events, and this is indeed controversial and still under investigation. Under no circumstances does the Cambrian Explosion imply a problem with finding a missing common ancestor, as the PA implies; such an idea is nonsense, because in evolutionary biology and phylogenetic reconstruction, common ancestors are always inferred, not "found." But I doubt that the creationists who wrote the PA would know that.
Vertebrate Embryos and Haeckel's Drawings
Ernst Haeckel, the famous 19th century German evolutionary biologist, proposed a "biogenetic law" that "ontogeny recapitulates phylogeny," that is, an organism's development (its ontogeny) goes through precisely the same stages that it historically went through during its evolution from a much more primitive ancestor (its phylogeny). While many ontogenetic stages of a vertebrate (including humans) are indeed similar to its phylogenetic history--thus graphically demonstrating the fact of evolution (for example, the human embryo develops a notochord and pharyngeal grooves or "gill slits," but these are lost during gestation)--they are not identical, so Haeckel was wrong.
To illustrate his recapitulation theory, Haeckel, an outstanding artist, produced a figure (reproduced below, from Richardson and others, 1997) that purported to show the embryonic stages of eight vertebrates (fish, salamander, turtle, chicken, pig, cow, rabbit, human). However, Haeckel exaggerated the similarities and drew the embryos, in their earliest stages, to appear to be identical (so as to better support his biogenetic law). This error was pointed out during his lifetime and periodically thereafter, but his illustration nevertheless found its way into introductory biology textbooks as a demonstration of evolution. This illustration, and re-drawings of it, should not be included in any biology textbook today, nor is it now. However, photographs and drawings from photographs that show the similarity of vertebrate embryos remain an excellent way to demonstrate the fact of evolution, and should be included.
Ernst Haeckel's Vertebrate Embryo Ontogeny Figure
From left: fish, salamander, turtle, chicken, pig, cow, rabbit, human (from Richardson and others, 1997)
Now, let's see how the Discovery Institute distorts this issue in its PA:Darwin believed that the similarity of vertebrate embryos in their early stages reveals their common ancestry, and he considered those embryological similarities "by far the strongest single class of facts in favor" of his theory.
Well, this is accurate, and still correct today. Embryological similarities are indeed excellent evidence to support the truth of evolution, and thus they should be included in introductory textbooks, since they are a vivid graphic example (that creationists therefore want to remove by political fiat).In fact, Haeckel's drawings misrepresent the evidence in three respects: They select from the wide variety of vertebrate embryos only those that come closest to fitting Darwin's theory, they distort those selected embryos to make them appear more similar than they really are, and they completely omit the embryos' earliest stages --in which their dissimilarity is evident. (The early dissimilarity of vertebrate embryos does not support Darwin's theory, but must be explained away by the theory.)
Here we go misleading again. Haeckel selected eight quite different vertebrate embryos, an appropriate number, to illustrate his, not Darwin's, theory of recapitulation. Only the earliest stages are distorted to make them identical, not the middle and last stages. Haeckel did indeed omit the very earliest stages of ontogeny (zygote, blastula, etc.), and these are indeed different for different vertebrate embryos, but he did this to favor his own recapitulation theory, not Darwin's theory, which was already accepted by biologists in Haeckel's time. The very early dissimilarity does not in any way cast doubt on evolutionary theory ("Darwin's theory"), but only on Haeckel's "biogenetic law." As I said before, the great similarity among various vertebrate embryonic stages (as pointed out by another German biologist of the 19th century, von Baer) strongly supports evolution.In 1997, a team of embryologists compared Haeckel's drawings with photographs of real vertebrate embryos. In an interview with the journal Science, the leader of the team stated: "It looks like it's turning out to be one of the most famous fakes in biology." In 2000, Harvard evolutionary biologist Stephen Jay Gould wrote that Haeckel's drawings of vertebrate embryos "exaggerated the similarities by idealizations and omissions. He also, in some cases--in a procedure that can only be called fraudulent--simply copied the same figure over and over again."
These are magnificent misleading quotes out of context, a sure-fire creationist tactic. The leader of the 1997 team, Michael Richardson, revealed Haeckel's duplicity in a long paper on evolutionary development that shows that vertebrate embryos in the tail-bud stage are often dissimilar. Richardson's 1997 paper never casts doubt on the fact of evolution; indeed, he explains the dissimilarities by invoking regulatory gene-controlled heterochrony during development, an important evolutionary process. Similarly, the late Stephen Jay Gould, in the paper quoted, after describing Haeckel's apparent fraud, explicitly points out that von Baer's original observation on the similarity of vertebrate embryos during ontogeny supports the fact of evolution very strongly."We do, I think, have the right," Gould wrote in 2000, "to be both astonished and ashamed by the century of mindless recycling that has led to the persistence of these drawings in a large number, if not a majority, of modern textbooks."
This statement is perfectly true, which is why all biology textbook authors and publishers today have already removed Haeckel's fraudulent drawings and replaced them with photographs or drawings from photographs to make the original point--which was never support for recapitulation, but an illustration of evolution.A few textbook authors have responded to criticisms by replacing Haeckel's drawings with photographs of actual vertebrate embryos. Even then, however, the selected embryos are usually the middle stages of chick and mammal embryos, which happen to resemble each other. Pictures of earlier stages, or the other vertebrate classes--which do not exhibit an obvious resemblance to each other--are omitted. Even though these textbooks are not recycling Haeckel's fraudulent drawings, they are still misleading students by showing them only that part of the evidence that happens to fit Darwin's theory, and omitting evidence that the theory has difficulty explaining.
Now we come to the crux of the matter. The DI creationists want all illustrations of evolution removed from textbooks, so they try to cast doubt on an important one and misleadingly say it is fraudulent and thus should be removed. But that's nonsense. I agree that the very earliest stages of vertebrate embryos are dissimilar, but that's only because they have different-sized eggs, an irrelevant factor. What is vitally important, however, is that students observe and understand the structural similarities of all vertebrate embryos--the pharyngeal pouches and grooves, the notochord, the dorsal nerve cord, the ventral blood vessel, etc.--that demonstrate their close evolutionary relationships. The presence of a notochord and pharyngeal grooves in the human embryo forcefully demonstrates our close ancestry to other vertebrates. This important information is precisely what the creationists duplicitously want the Texas SBOE to remove--because it is such a powerful illustration of evolution. The creationists don't really want information added; they want to make the vertebrate embryo illustration so controversial that the Board or--more likely--the publishers will remove it completely. In fact, one publisher (Holt, Rinehart, Winston) already has.
The evolution of peppered moths is an excellent illustration of gene-controlled microevolution (but not speciation) under natural selection. The moths vary from light-colored to dark-colored depending on the degree of industrial pollution, since selection pressure from predators forces the moth population in one direction or another, depending on the shade of tree trunks and branches, which is a function of soot pollution (which darkens trees) and lichen growth in unpolluted regions (which lightens trees). Genes control the expression of melanin in wing scales, so this process is termed "industrial melanism." As an illustration of the fact of natural selection, the peppered moth example is unequaled, which is why creationists want to remove it from textbooks, or more precisely, want to make it controversial enough so that the publishers will remove it themselves (self-censorship) under pressure from the SBOE.
The original work was conducted by Bernard Kettlewell in the 1950s, but scientists today are continuing the research with excellent results. The controversial point focused on by the PA is that an illustration of light and dark moths on both dark and light trunks was artificially reconstructed (or, as they say, "staged"). Two dead moths, one light and one dark, were indeed glued to two different trees, one light and one dark. Kettlewell did this deliberately for two excellent scientific reasons: first, to be able to illustrate the moths on their natural resting places for his paper, and second, to see whether predators would indeed preferentially choose the dark moth on the light trunk and the light moth on the dark trunk (they did). The real experiment took place after this and it was not "staged": different moths were released and then captured in a restricted area to measure predation. The results showed that the selection pressure was real. All this was done, of course, after other biologists had captured hundreds of moths throughout England, noted the color differences, and proposed the hypothesis of industrial melanism, which Kettlewell experimentally confirmed. Even more spectacularly, industrial pollution had darkened most regions of England, resulting in high numbers of dark moths in the population, but when cleaner coal plants and environmental regulations began appearing in the 1960s, the moth population shifted to more light-colored.
The peppered moth deserves to be kept in biology textbooks as an illustration of the action of natural selection, but what does the PA say about it?In the 1960s, legislation reduced industrial pollution, and light moths made a comeback. Their comeback in many locations, however, preceded significant changes in the color of tree trunks, raising questions about the classical story. By the 1980s, it became clear that peppered moths don't normally rest on tree trunks. In several decades of field research, involving tens of thousands of moths, only 47 were found resting in the wild, and only six of those were found in exposed positions on tree trunks. The textbook photographs, it turns out, were staged--in many cases by pinning or gluing dead moths to tree trunks.
The second sentence is false: enough trees had changed color to permit the light moths to reappear in greater numbers. Yes, moths don't normally rest on tree trunks, but that's irrelevant. Moths normally rest under branches, which show the same color-changes as the trunks. The "staged" photographs are a perfectly normal part of scientific illustration; what was Kettlewell supposed to do--wait for months until a moth landed in front of his camera on a tree trunk?In the 1950s, when experts still believed that peppered moths naturally rest on tree trunks, Kettlewell's experiments seemed valid and there was nothing wrong with staging photographs. But when it became clear that the basic premise of the classical story was false, textbooks should have started alerting students to the fact. The staged photographs should have been dropped, or at least properly labeled. Commercial enterprises are legally required to label their products and advertisements honestly; science textbooks should do no less. . . . There is simply no excuse for textbook writers to continue misinforming students about the peppered moth story, much less accompanying the story with false and misleading photographs.
I repeat, there was nothing wrong with illustrating artificial situations, and I have no problem with textbooks mentioning that fact in the figure caption. But it is important for the books to also point out that the real experiment did not involve moths artificially pinned or glued to tree trunks, but used release and capture statistics and other observational methods to test the hypothesis of industrial melanism. However, the DI creationists don't really just want the figure caption changed; they want the entire peppered moth example removed from biology textbooks because it is such a good illustration of the fact of natural selection. This example should not be removed.
Answers to Additional Questions About Evolution
Some SBOE members asked me some additional questions about evolutionary theory after the hearing on July 9. I will answer them again here for the benefit of all members.
1. Please explain the difference between microevolution and macroevolution.
Evolution in nature is a continuous process: there is unbroken genetic continuity from the earliest common ancestor to all present-day organisms. Scientists, however, have designated artificial hierarchies or levels of this continuous process so that they can discuss it simply and coherently. Microevolution is the change in gene allele frequencies in the gene pool of a species population that ultimately culminates in speciation--the origin of a new species. Macroevolution is the evolution of all taxa higher than species and uses speciation as the basic mechanism (taxa include genera, classes, families, orders, phyla, etc.). Microevolution is easily observable in both laboratory and field populations of organisms, while macroevolution is so slow that it must be inferred from systematics, phylogenetic studies, and the fossil record.
The big question is to what degree is microevolution able to account for macroevolution; some scientists believe that there must be some natural processes that operate only on the macroevolutionary level to explain the diversity we observe, while others believe that microevolution alone is sufficient to explain it. Whatever the case, it is important to understand that organisms do not evolve by either microevolution or macroevolution; there is only one, continuous evolutionary process that scientists have artificially subdivided for conceptual and explanatory reasons. So it is inaccurate to say, "I believe in microevolution but not macroevolution." However, one could correctly say either, "I believe that microevolution alone accounts for all the macroevolution we observe," or "I believe that separate processes are occurring in both microevolution and macroevolution." Some microevolutionary processes include natural selection, genetic drift, recombination, crossing-over, random mating, etc. Some macroevolutionary processes include the founder effect, species selection, species sorting, mass extinctions, macromutations, etc.
2. What are some of the legitimate scientific controversies, problems, or issues inviting criticism about the theory of evolution?
There are many disagreements among scientists about the correct nature or explanation of the evolutionary process. These should be studied in a university evolution class, usually taught in the senior year because of the great amount of prior biological knowledge needed to understand the issues. Their existence indicates that evolutionary science is a very healthy, active, and productive field. Here are some of them, including all the most contentious ones:A. The sufficiency of microevolution to explain macroevolution v. the existence of specific macroevolutionary processes such as mass extinction, species selection, macromutation, etc.
B. Disagreements about the tempo and mode of evolution under different circumstances: slow v. fast, gradual v. punctuated, before and after a mass extinction event, background evolution v. adaptive radiation, etc.
C. Adaptation of all features in evolution via natural selection v. features resulting from non-adaptive events and processes, such as correlation of growth, body constraints, neutral theory, genetic drift, etc.
D. The role of contingency and non-progression in evolutionary history v. evolutionary progress, improvement, and repetition due to convergent evolution.
E. Disagreements about the primacy of natural selection of individuals compared to other levels of the evolutionary hierarchy, such as gene selection, group selection, and species selection.
F. Nature v. Nurture, Genes v. Environment--this is the most divisive controversy. There are at least three positions: blank slate/human potential proponents v. sociobiologists and evolutionary psychologists v. biological determinists and IQ and race investigators.
G. The extent to which evolutionary theory can explain or account for human morality, religion, behaviors, self-awareness, free will, etc.
H. The reality or not of memes in the human population; memes are similar to genes, but are actually ideas or concepts that evolve throughout the human population and are affected by similar processes that affect genes, such as natural selection, genetic drift, founder effect, etc. Memes affect cultural evolution in the same way that genes affect physical evolution.
3. If evolutionary theory is truly scientific, it must be testable and falsifiable. What observations would falsify the process of evolution by natural selection?
Charles Darwin himself suggested two such tests. First, he said that any structure or feature possessed by an organism that benefits another species but not the one that possesses it would falsify his theory (evolution by natural selection). Second, any structure or feature that exists today that can be shown to be impossible to form by gradual steps would falsify his theory. Neither of these two tests has ever successfully revealed that evolution by natural selection is false: no observation has ever been made that shows the presence of such unbeneficial structures or the impossibility that any structure formed gradually. Another test would be out-of-place fossils; e.g. human fossils in the Cambrian with trilobites or in the Jurassic with dinosaurs; such fossils have never been found. Since evolution is usually defined as the change of gene allele frequencies through time in species populations, another test would be finding two different species that possess identical alleles; such species have never been discovered; indeed, only identical twins or clones have identical alleles. Evolution predicts that organic taxa will appear in nature as groups within groups; that the genes essential for the most basic cellular processes (such as genes for mitochondria, cellular respiration, ribosomal proteins, etc.) will be conserved though high-level taxa (yeast, protist, roundworm, insect, vertebrate) through billions of years; that transitional fossils and living forms will be discovered between different fossil and living taxa: the absence of corroborating evidence for these predictions would tend to falsify evolution, yet all have been repeatedly confirmed.
Dr. Steven Schafersman is an evolutionary scientist who for over two decades has taught biology, geology, paleontology, environmental science, oceanography, and petroleum geology at the University of Houston, Houston Community College, Miami University of Ohio, and the University of Texas of the Permian Basin. He has also taught chemistry and biology at Permian High School in Odessa, TX. He earned his Ph.D. from Rice University in 1983 for research on the evolution of fossil marine zooplankton. He founded and was president of the Texas Council for Science Education during 1982-1994, when he helped to improve the quality and integrity of biology and geology textbooks and science curricula in Texas. He founded the Texas Citizens for Science in early 2003 to meet the new threats to science education in Texas. The Texas Citizens for Science website is at www.txscience.org.
Copyright © 2003 by Steven Schafersman Texas Citizens for Science Last updated: 8 September 2003