Explore Evolution The Arguments for and Against Neo-Darwinism


The critique by the National Center for Science Education (NCSE) of the chapter on anatomical homology in Explore Evolution (EE) begins by misrepresenting EE’s treatment of the subject.[1] The NCSE claims that EE “never provides a clear and consistent definition of homology,” and that EE “repeats the erroneous creationist canard of claiming that homology’s definition is circular.” Both of these claims by the NCSE are false.

First, EE provides a clear definition in its glossary: “Homologous structure: a body part that is similar in structure and position in two or more species but has a different function in each; for example, the forelimbs of bats, porpoises and humans.” (p. 146)

In addition, EE’s chapter on anatomical homology begins with the following:

“Why should the pig’s forelimb and your own arm have the same skeletal pattern? After all, the pig uses its forelimbs mainly for locomotion—getting around the pen. You use your arms and hands for a wide range of tasks, such as catching a baseball, typing a report, or lifting a box—but not for locomotion. Many biologists before Darwin thought that these similarities (called “homologies”) were due to a common plan or “archetype” But Darwin rejected this idea. Instead, he said these homologies were best explained by his theory of descent from a common ancestor.” (p. 40)

So EE defines homology classically, as similarity of structure and position. Not surprisingly, the NCSE rejects this definition, in favor of the Darwinian definition of homology as similarity due to common ancestry. But the NCSE’s charge that EE fails to define homology is completely unfounded.

Second, EE explains that if “homology” is redefined to mean similarity due to common ancestry, then it cannot be used as evidence for common ancestry without arguing in a circle:

“If homology is defined as ‘similarity due to common descent,’ then to say that homology provides evidence for common descent is to reason in a circle.” (p. 49)

So it is not the Darwinian definition per se that is circular; what is circular is arguing that homology thus defined provides evidence for common ancestry. That would be equivalent to arguing that similarity due to common ancestry is due to common ancestry.

According to the NCSE, biologists do not make this obvious mistake. Yet the 1999 edition of Teresa and Gerald Audesirk’s Biology: Life on Earth explains that “internally similar structures are called homologous structures, meaning that they have the same evolutionary origin,” and on the very same page states that homologous structures “provide evidence of relatedness in organisms.” Along the same lines, the 1998 edition of Sylvia Mader’s Biology declares: “Structures that are similar because they were inherited from a common ancestor are called homologous structures;” on the same page, the book claims: “This unity of plan is evidence of a common ancestor.” According to the 1999 edition of Raven and Johnson’s Biology, homology refers to “structures with different appearances and functions that all derived from the same body part in a common ancestor,” yet the book also claims that homology is “evidence of evolutionary relatedness.” And the 1999 edition of Campbell, Reece and Mitchell’s Biology contains the following: “Similarity in characteristics resulting from common ancestry is known as homology, and such anatomical signs of evolution are called homologous structures. Comparative anatomy is consistent with all other evidence in testifying [to] evolution.”[2]

Even Douglas J. Futuyma’s 2005 college textbook Evolution (which the NCSE cites as an authority in this matter) makes the same mistake. Futuyma defines homology as “possession by two or more species of a character state derived, with or without modification, from their common ancestor,” but in a section titled “Evidence for Evolution,” he includes homology among the categories of evidence that are “more than sufficient to demonstrate the historical reality of evolution: all organisms have descended, with modification, from common ancestors.”[3]

The NCSE claims that evolutionary biologists overcome the circularity by relying on more than one character to infer common ancestry: “Biologists do not look at only one line of evidence to infer common descent; it is the agreement of multiple lines of evidence about morphological, genetic, behavioral ecological and developmental similarity which allows that inference.” Yet, as EE states, these different lines of evidence are often inconsistent with each other. In a later section of its critique, the NCSE itself actually acknowledges that there are disparities among the morphological, genetic and developmental evidence, though it attempts to explain them away. What the NCSE and other Darwinists never do, however, is question common ancestry itself. They simply assume that common ancestry is true, then they use homology to test subsidiary hypotheses based on that assumption.

Berkeley evolutionary biologist David B. Wake wrote in 1999 that “homology is the anticipated and expected consequence of evolution. Homology is not evidence of evolution.”[4] EE quotes Wake’s second sentence (p. 49), and the NCSE claims that EE misquotes him. But Wake’s point is unmistakable: Homology is a theoretical deduction from Darwinism, not evidence for it.

Is this how science is supposed to work? Philosopher of biology Ronald Brady wrote in 1985: “By making our explanation into the definition of the condition to be explained, we express not scientific hypothesis but belief. We are so convinced that our explanation is true that we no longer see any need to distinguish it from the situation we were trying to explain. Dogmatic endeavors of this kind must eventually leave the realm of science.”[5] 

References Cited

[1] National Center for Science Education. 2008. Section on “Anatomical Homology” in the NCSE critique of Explore Evolution. Available at https://ncse.com/creationism/analysis/anatomical-homology as of Feb. 23, 2009.

[2] Teresa Audesirk and Gerald Audesirk, Biology: Life on Earth (Upper Saddle River, NJ: Prentice Hall, 1999), p. 264; Sylvia S. Mader, Biology, Sixth Edition (Boston: WCB/McGraw-Hill, 1998), p. 298; Peter H. Raven & George B. Johnson, Biology, Fifth Edition (Boston: WCB/McGraw-Hill, 1999), pp. 412, 416; Neil A. Campbell, Jane B. Reece & Lawrence G. Mitchell, Biology, Fifth Edition (Menlo Park, CA: Addison Wesley Longman, 1999), p. 424.

[3] Douglas J. Futuyma, Evolution (Sunderland, MA: Sinauer Associates, 2005), pp. 48-49, 549. 

[4] David B. Wake, “Homoplasy, homology and the problem of ‘sameness’ in biology,” pp. 24-33 and 44-45 in Homology (Novartis Symposium 222; Chichester, UK: John Wiley & Sons, 1999), pp. 45, 27.

[5] Ronald H. Brady, “On the Independence of Systematics,” Cladistics 1 (1985): 113-126, p. 117.

Launch of Explore Evolution “Further Debate” Website

Since its publication in 2007, the innovative science textbook Explore Evolution: The Case For and Against Neo-Darwinism has helped trailblaze a new way of teaching about evolution, one based on Charles Darwin’s own acknowledgment that “a fair result can be obtained only by fully stating and balancing the facts and arguments on both sides of each question.” The original goal of Explore Evolution was to provoke discussion about Darwinian evolution, and provoke discussion it has! This week Discovery Institute launches an extensive “Further Debate” website inspired by the book in the hope of encouraging even more discussion. The new site offers cogent responses to a variety of reviews of the book issued by Darwinists over the past two years, including Read More ›

Explore Evolution Author Responds to Critics

CSC Fellow and Explore Evolution co-author Paul Nelson has a substantive series of responses to biologist and science writer John Timmer’s online critique of the biology textbook: On September 24, 2008, biologist and science writer John Timmer published an online review of the supplementary biology textbook Explore Evolution (EE). Timmer had previously written about EE without having read it, so Discovery Institute sent him a copy. Alas — having EE in his hands improved neither the quality of Timmer’s writing about the book, nor indeed his coverage of the relevant science. In fact, Timmer so baldly misrepresents both the content of EE, but especially the associated scientific evidence and controversies, that his review perfectly illustrates the need for a book like EE. Dr. Nelson’s Read More ›

Explore Evolution Errata Sheet (October 2008)

An updated errata sheet is now available for the first edition of Explore Evolution: The Arguments For and Against Neo-Darwinism (2007 Hill House Publishers) Click here to download errata sheet.

Explore Evolution Favorably Reviewed by Kirkus

The groundbreaking textbook, Explore Evolution: The Case For And Against Neo-Darwinism (Hill House Publishers 2007), continues to make inroads in science education. Recently Kirkus Discoveries issued a fair and favorable review of Explore Evolution saying: “through succinct language and extensive use of illustrated sidebars and summary boxes, an impressive amount of terrain is covered in a colorful and lively fashion.”  Here is the full review:  Two microbiologists, two philosophers of science and a technical writer present for students a concise introduction to the cases, both pro and con, regarding major aspects of neo-Darwinian evolutionary theory. Within the evolutionary-biology realm, the authors explore how Darwin’s theories of natural selection and universal common descent are faring these days. They use an inquiry-based approach: point, counterpoint. The book’s brevity precludes Read More ›

No, We Didn’t Make Up The Controversies — A Reply to John Timmer

Does the biology textbook Explore Evolution manufacture false controversies about evolution, while ignoring real ones? That’s what biologist and science writer John Timmer claimed in a post earlier this week at Ars Technica. Timmer attended a two-day symposium on evolution at Rockefeller University and noted the many debates brewing there. “Evolution clearly has no shortage of controversies,” he concluded . But those real controversies have “no overlap,” he claimed, with the “ostensible” (i.e., fake) controversies supposedly “manufactured” by Explore Evolution. Bottom line for Timmer: while students may, or may not, need to learn about controversies in evolution — he leans strongly towards “not” — Explore Evolution is misleading at best, and the academic freedom bills being introduced around the country aren’t needed. Now, when he wrote his blog Read More ›

Explore Evolution In the Boston Globe

Recently the Boston Globe ran a letter to the editor by Stephen Meyer, responding to Sally Lehrman’s ridiculous claim that the Explore Evolution textbook “uses pseudoscience to attack Darwin’s theories.” Meyer’s response? There’s nothing “pseudo” about saying what the evolutionists themselves admit, even citing the National Research Council of the National Academy of Sciences. Perhaps Lehrman judges our book pseudoscience because we also describe current scientific criticisms of evolutionary theory. Perhaps she is unaware that skepticism about the creative power of natural selection and random mutation is common in peer-reviewed scientific literature and in the scientific community. No less an authority than the National Research Council of the National Academy of Sciences published a recent paper stating: “Natural selection based solely on mutation is probably not an adequate mechanism Read More ›

WORLD Magazine Cover Story on New Biology Textbook Explore Evolution

A recent WORLD Magazine cover story is about teaching the controversy and focuses primarily on Explore Evolution, the new textbook which teaches both the strengths and weaknesses of Darwin’s theory. The article features an interview with Discovery senior fellow Dr. John West, along with Doug Cowan, a high school biology teacher who plans on incorporating the textbook in his curriculum next year. According to the article:  This fall, the 34-year teaching veteran will restructure his evenhanded presentation around a new textbook from the Seattle-based Discovery Institute. Explore Evolution: The Arguments for and Against Neo-Darwinism (Hill House Publishers, 2007) does not address alternative theories of origins but succinctly lays out the scientific strengths and weaknesses of the most critical elements of Darwinism. “It’s made my work a Read More ›

New Textbook Seeks to Improve Teaching of Evolution by Promoting Inquiry-Based Approach

Explore Evolution: The Arguments For and Against Neo-Darwinism (Hill House Publishers Ltd., Melbourne and London, 2007) is the first biology textbook to present the scientific evidence both for and against key aspects of Darwinian evolution. “Sadly, the majority of biology textbooks in use today are dumbed-down and do a poor job explaining evolution,” said Dr. John West of Discovery Institute, the book’s United States distributor. “Explore Evolution will improve the teaching of evolution by providing teachers and students with more information about evolution than they are likely to find in any other textbook written at the same level.” West is Associate Director of the Institute’s Center for Science and Culture. Explore Evolution promotes inquiry-based learning, encouraging students to participate in the process Read More ›

Explore Evolution Errata Sheet (May 2007)

Page 27, left-hand column, first paragraph, first sentence: Should read: Though a possible land-dwelling mammal to fully aquatic mammal (cetacean) transitional sequence has recently been uncovered, critics maintain that transitional sequences are rare, at best. Page 129, 4th complete paragraph, second sentence: Should read: Most reptiles lay eggs, while mammals carry fertilized eggs internally, which they nourish through a placenta, and bear live young.

The Arguments for and Against Neo-Darwinism