Icons of Evolution? Why Much of What Jonathan Wells Writes about Evolution is Wrong Alan D. Gishlick, National Center for Science Education HAECKEL’S EMBRYOS to be central to our understanding of evolution. Comparative embryology shows how different ERNST HAECKEL AND adult structures of many animals have the COMPARATIVE EMBRYOLOGY same embryonic precursors. These shared rnst Haeckel (1834–1919) is both a hero developmental features suggest that many ani- and a villain in the biological communi- mals have ancestors in common. Further com- Ety. He was a prominent figure in the late parative embryology shows that closely relat- nineteenth-century comparative anatomy com- ed animals show a unity of developmental pat- munity and is famous for his phylogenetic tern, particularly in earlier stages, and have trees, anatomical illustrations, support for evo- more developmental features in common than lution, and strong personality. He is perhaps as do more distantly related organisms. The fact well known, and considerably misunderstood, that certain incipient structures such as pha- for his studies in embryology and his dictum ryngeal pouches or arches exist in all verte- that “ontogeny recapitulates phylogeny,” brate embryos yet develop into very different called the Biogenetic Law. Haeckel espoused adult structures suggests that they all share a the view that evolution generally proceeds by common ancestor whose embryo had pharyn- placing each innovation on top of a previous geal pouches (at least at some stage in devel- opment). In this way, developmental similari- one, like adding layers on a cake. Therefore, ties that are inherited from a common ancestor the embryo of an “advanced” organism should are homologous, just like the patterns of bones pass through (“recapitulate”) the adult stages in adult limbs. of more “primitive” forms as it develops. However, repeated observations of develop- DEVELOPING AN ARGUMENT ment by other workers (e.g., Wilhelm His, ells’s entire chapter on embryology Walter Garstang, Wilhelm Roux, Adam amounts to little more than a mis- Sedgwick, Gavin de Beer, and others; see Wreading of Darwin, Haeckel, and Gilbert, 1991, or Gould, 1977 for a detailed others, combined with a general failure to history) clearly showed that embryos do not go acknowledge recent work on Haeckel and his through adult stages of lower forms; rather, embryos by Gould, Richardson, and others. In they share many common features in develop- it, he conflates ideas in history of developmen- ment. No biologist has accepted the biogenetic tal biology with ideas of contemporary devel- law for many decades and it may have been a opmental biology. He also fails to recognize caricature of Haeckel’s actual views anyway. close to 60 years of work in developmental Much of Haeckel’s developmental work is biology and thus completely omits any discus- now considered invalid, and some historians of sion of the real developmental evidence for science have provided reasonable evidence to evolution. It almost seems that Wells’s goal is suggest that he manipulated his drawings to fit to discredit the entire field of comparative his preconceived views about development embryology by proxy, employing a bait-and- and evolution. Haeckel’s views about the pro- switch between Haeckel and Darwin. Wells’s gressive nature of evolution are no longer ploy is reminiscent of a child’s false logic accepted. proof. It goes like this: Darwin relied on Regardless of Haeckel’s accuracy or precon- Haeckel, Haeckel was a fraud, therefore ceptions, comparative embryology continues Darwin is a fraud. 29 Icons of Evolution? Why Much of What Jonathan Wells Writes about Evolution is Wrong Alan D. Gishlick, National Center for Science Education The charge that Ernst Haeckel intentionally go through the adult stages of their ancestors “faked” his drawings is irrelevant. Regardless — with the idea that shared features of of his intent, the drawings that Haeckel made embryos give insight into their phylogenetic are incorrect, especially in what he labeled as relationships. Failing to distinguish these the “first stage.” But it really does not matter allows Wells to avoid dealing with the actual what Haeckel thought or whether his drawings evidence for shared developmental features in are accurate: modern comparative embryology various embryos and to dismiss the entire field does not stand or fall on the accuracy of as based on an outdated and outright refuted Haeckel any more than modern physics stands claim, one that embryologists know to be false or falls on the accuracy of Kepler or Newton. but cling to anyway because of an ideological Historically, Wells actively ignores the accu- commitment to evolution. Wells should know rate work of many of Haeckel’s predecessors better, as the holder of a Ph.D. in cell and and contemporaries (such as William and developmental biology. Jeffrey Parker, Hans Gadow, Hans Selenka, REWRITING HISTORY FOR Heinrich Rathke, Virgil Leighton, Hugo THE GREATER GLORY OF Schauinsland, and Alfred Voeltzkow, to name THE REV. MOON a few). Haeckel and von Baer were not the only embryologists in nineteenth-century sci- n the introduction to Icons, Wells states ence, but you wouldn’t know that from reading that he first became aware of the problems Wells. Worse, Wells speciously extends his cri- Iin evolutionary theory when he was “fin- tique of Haeckel to the present day. Wells ishing his Ph.D. in cell and developmental implies that textbooks misrepresent the study biology” (Wells, 2000:xi). He claims that he of developmental programs as evidence for knew that the drawings of embryos presented evolution by accusing them of using Haeckel’s in textbooks were false because he was a inaccurate drawings, in effect accusing text- developmental biologist. Shortly thereafter, he books that show any embryos of “mindlessly claims, his observation was confirmed by repeating” Haeckel. The important question is other scientists. Before that seminal event, he whether textbooks, and more importantly says, “I believed almost everything I read in developmental biologists, still rely on my textbooks” (Wells, 2000:xi). This state- Haeckel’s work. The answer is no, but that ment is inconsistent with other claims of doesn’t stop Wells from acting as if they do. Wells’s. According to statements made by Wells sets up a straw man in his bait-and- Wells in a sermon on a Unification Church switch, starting with Darwin’s famous asser- website (http://www.tparents.org/library/unifi- tion that embryology represented the “single cation/talks/wells/DARWIN.htm), he went to strongest class of facts” in favor of his theory. graduate school with the specific intent of Here Wells misrepresents both early embryol- attacking evolution: “Father’s words, my stud- ogy and Darwin’s own words. When quoting ies, and my prayers convinced me that I should both Darwin and other historical figures, he devote my life to destroying Darwinism” and quotes them out of context, leaves out impor- he believed that its weakest point was devel- tant parts of quotes, and even changes the opmental biology. “I was convinced that order of their appearance, all to misrepresent embryology is the Achilles’ heel of their real meaning and intent. Wells also con- Darwinism; one cannot understand how organ- flates “recapitulation” — that is, that embryos isms evolve unless one understands how they 30 Icons of Evolution? Why Much of What Jonathan Wells Writes about Evolution is Wrong Alan D. Gishlick, National Center for Science Education develop. In 1989, I entered a second Ph.D. pro- ed to developmental ones) to generate classifi- gram, this time in biology, at the University of cations for organisms. Darwin is praising the California at Berkeley. While there, I studied application of his theory by Haeckel. embryology and evolution.” So it was not so Although Darwin did not use Haeckel on much a “revelation” as it was a plan. If Wells embryology, he did use von Baer. Recognizing is so revisionist about his own history, how can Darwin’s use of von Baer, Wells then accuses we trust him with the history of science? Darwin of “misusing” von Baer’s work, twist- ing the data to fit his views. But Darwin does DEVELOPMENTAL ANATOMY, not. Wells claims that von Baer’s embryologi- DARWIN, AND EVOLUTION cal laws are incompatible with Darwin’s con- ells opens the chapter by telling us clusions, but they are not. Von Baer may have what Darwin thought about devel- disagreed with Darwin about his conclusions, Wopment and evolution. Wells uses but his laws do not prohibit development elu- about 5 different quotes from the Origin in an cidating common ancestry. Darwin came to a attempt to show that Darwin was advocating different conclusion from the same body of recapitulation in spite of what the data showed. evidence — this is not “distorting” the evi- To do this, he distorts the history. Wells tries to dence. Darwin was making a general inductive connect Darwin to Haeckel so that he can use argument and searched for data that could test that to dismiss Darwin. Wells says that Darwin the general proposition of common descent; he was not an embyrologist and thus he relied on argued that von Baer’s data could be reinter- Haeckel (Wells, 2000:81). Anyone familiar preted in terms of common ancestry. This was with the history of biology knows that this is no more a “misuse” of von Baer than was impossible. Haeckel did not publish his Alfred Wegener’s reinterpretations of the data Anthropogenie until 1874 (where the much- of geology in light of mobile continents. New maligned embryo drawings first appear), 15 scientific theories always use previous data. Is years after the publication of the Origin. (It Wells implying that evolutionary biology can- should also be noted that the drawings referred not cite any research that predates 1859? Is to by Wells [2000] are not from Haeckel but Wells implying that developmental sequences redrawn from the first edition of such as those illustrated by von Baer and oth- Anthropogenie in a textbook by Romanes ers are not data? [1892; see figure 10a]. In later editions of That Darwin and all modern evolutionists Anthropogenie, Haeckel corrected some of the advocate some form of the “Biogenetic Law” errors of the first edition drawings [Richardson is the central falsehood of this chapter; in fact and Keuck, 2002; personal observation].) the entire “resurrecting recapitulation” section Wells quotes Darwin’s praise of Haeckel in his does nothing but assert this. But Wells fails to sixth and final edition of the Origin in such a explain fully what recapitulation means. There way as to obscure the fact that Darwin lauds are a number of meanings for “recapitulation” Haeckel for his phylogenies, not his embryol- that Wells conflates in order to tar the entire ogy. The quote is not even from the embryolo- field of embryology with a biogenetic brush. gy section of the book; rather it comes from As he says in a footnote, a “plain reading” of the classification section, in the final sentence Darwin shows that Darwin was advocating of which Darwin praises Haeckel for using recapitulation — but just what kind? (1) An homologous features (including but not limit- embryo of an “advanced” form goes through 31 Icons of Evolution? Why Much of What Jonathan Wells Writes about Evolution is Wrong Alan D. Gishlick, National Center for Science Education all the adult stages of all its ancestors. This is a tion from von Baer. Does “earliest” reflect caricature of Haeckelian recapitulation, which Darwin’s belief, or is he merely reporting von is false, and few scientists ever believed it any- Baer’s? This is important because numerous way. (2) Evolution proceeds as an “add-on” scholars have made the mistake of confusing process so that there is a general progression of Darwin’s reporting of what others thought with embryological stages from “primitive” to his expression of his own views (Padian, “advanced” forms. This more traditional read- 1999). So apparently has Wells. But it really ing of recapitulation is also false and has not does not matter what Darwin thought: just as been accepted for nearly a century. (3) All modern embryology does not rely on Haeckel, closely related organisms go through all the neither does modern evolutionary biology same stages of development and always look slavishly follow Darwin’s beliefs. similar. This is vague: how closely related is It is also important to understand what nine- closely related? How are the stages individuat- teenth-century scientific workers may have ed? But however these questions are answered, meant by the use of “embryo” and “early this reading of recapitulation would generally stage.” For many workers in the nineteenth be agreed to make too sweeping a claim. (4) century, developing organisms weren’t called Some parts of developmental sequences (and embryos until they reached the tailbud (phylo- some specific characters of them) in closely typic) stage. During earlier stages, they were related animals share more specific similarities called “developing ovum” or “developing egg” (in pattern, sequence, position, etc. of develop- (see Barry, 1839, or just about any embryolo- mental features) with each other than with gy work from 1820 to 1900). What this means those of more distantly related animals. That’s is that Haeckel, von Baer, and others, have a basically true. All modern biologists recognize different meaning for “early embryo.” Yet that all stages of development are open to Wells interprets them using modern defini- modification. This is generally the type of tions. “recapitulation” accepted by the post- Wells also criticizes the field of comparative Haeckelian embryologists (such as Frank embryology for the way it chooses its data and Lillie) cited by Wells, as well as by current for its names for embryonic structures. First, embryologists, but Wells treats it derisively as Wells emphasizes the disparity of “earliest” if it were exactly what Haeckel thought. developmental stages, accusing biologists of Finally, a “plain reading” of Darwin shows “choosing” taxa (animals) that look most sim- that he was suggesting something between (2) ilar for illustrations in textbooks and else- and (3); even though he was not an embryolo- where. He criticizes Haeckel for not using ani- gist, he had a more sophisticated notion of mals such as monotremes in his work. But embryology and development than does Wells. developmental sequences for monotremes Wells chides Darwin and nineteenth-century were not available in 1874. Monotreme devel- embryologists for saying that the “earliest” opmental sequences were not known or stages of development are similar when in fact described until 1884 (Caldwell, 1887; Hughes they are not. However, “earliest” is Wells’s and Hall, 1998), and it was the developmental word, not Darwin’s. It does not appear in any features monotremes shared with marsupials of the quotes that Wells uses. Indeed, in the that led Caldwell to conclude that monotremes entire section on embryology in the Origin, the were indeed mammals (Caldwell, 1887). Was word “earliest” only appears once, in a quota- the sample of organisms available to Haeckel 32 Icons of Evolution? Why Much of What Jonathan Wells Writes about Evolution is Wrong Alan D. Gishlick, National Center for Science Education

Figure 8. Developmental sequences of various vertebrates shown in phylogenetic context. Note the shared similarities of some closely related taxa, particularly the amniotes (modified from Richardson et al. 1998). biased? Yes, but only in the sense that early sexual maturity, rapid reproduction, ability for embryologists worked with the animals that development to occur in the laboratory, and were available to them. Most specimens of ability to live indoors for several generations “exotic” animals were shipped to researchers (Bolker, 1995). They were not chosen to “sup- by explorers and received in varying states of port evolution” as Wells implies. In fact, the decay (Caldwell, 1887). Most nineteenth-cen- model organism that is the subject of Wells’s tury embryologists loved to describe the devel- own dissertation, Xenopus, was not the origi- opment of any animal they could. And Haeckel nal “model” amphibian. The discovery that was continually updating and adding new Xenopus does not need a breeding season was organisms to his embryonic series as they a boon to embryologists and led to its came available. Contrary to what Wells serendipitous adoption as a model organism implies, there was no attempt to limit the data, (Gurdon and Hopwood, 2000). How Wells and the sample was not “chosen” for any par- knows that “model organisms” were chosen to ticular reason. mislead is unclear, especially given his own Today, embryologists work mainly with use of model organisms later in his chapter. “model organisms,” which were largely cho- Wells doesn’t show developmental sequences sen for practical reasons such as ready avail- for any of the organisms he complains others ability, small body size, large litter size, rapid don’t show. Why not? Because there is no evi- 33 Icons of Evolution? Why Much of What Jonathan Wells Writes about Evolution is Wrong Alan D. Gishlick, National Center for Science Education dence for his insinuation that developmental Second, they are not all scaled the same. In the biologists treat their data selectively in order to figure showing the neural crest infolding, the hide something. The fact that embryologists turtle and chicken are shown at a large scale, tend to present, at least in textbooks, develop- neglecting the large yolk they sit on, while the mental sequences for which there is good data human is shown as part of the whole develop- does not refute the idea that closely related ing ovum, so that the germinal disc and primi- taxa, should, and do, have more shared simi- tive streak formation are shown differently, larities in developmental programs than more even though it is shared by all amniotes distantly related taxa (Figures 8, 9). Wells tries (Schaunislaund, 1903; Nelson, 1953; Cruz, to support his claim by using a quote by 1997; Schoenwolf, 1997; Figure 9). Also pic- Darwin in which he states that embryos of the tured is a frog embryo, despite its indirect same “class” are most similar in their earliest development, which is very different from that stages. Wells then says that the quote is false, of the other vertebrates pictured. Many of the and cites how the different “classes” of verte- general “differences” in early embryo develop- brates are very different in their “earliest” ment that Wells mentions are a result of organ- stages. This is merely a semantic sleight-of- ization due to the yolk size rather than being hand, a bait-and-switch. Darwin is not talking specific differences in the basic body-plan of about different “classes.” Wells leaves out the embryo (Arendt and Nübler-Jung, 1999). important information, as usual. Embryos do reveal phylogenetic informa- In the figures of embryos (Wells, 2000:95, tion in terms of specific shared features, shared especially stage 4, “gastrulation”), Wells’s early developmental features such as the for- illustrator resorts to a number of graphic tricks mation of a germinal disc and primitive streak in order to make the embryos appear more dif- in all amniotes or the neural crest cells of all ferent than they are. First, the embryos are not vertebrates. The presence, and sequence of shown from the same rotational angles. The development, of eyes, ears, somites, limbs, chicken is shown in a different position than guts, nerve cords, tails, organs, etc. are indi- the other “Haeckel’s first stage” embryos. vidual features that no one would deny are

Figure 9. Embryos of various amniotes shown during somite stage. All amniotes go through the same sequence of development: primitive streak–neural tube–somite formation.

34 Icons of Evolution? Why Much of What Jonathan Wells Writes about Evolution is Wrong Alan D. Gishlick, National Center for Science Education present in vertebrates and not present in the the letter and spirit of the concepts and authors same way in other animals. These are individ- he presents do little to inspire confidence in ual characters whose developmental features what he says about Haeckel or embryology in are treated as shared features in reconstructing general. Even if Wells were right about vertebrate evolution; these features do not Haeckel’s work and Darwin’s use of it, what always have to be in agreement, and some ani- Haeckel and Darwin thought doesn’t matter; mals can show unusual derived features early embryology has moved beyond them. Wells in development, such as the snake’s tail needs to show a lack of specific similarities to (Figure 8). support his case. Is Wells actually claiming Wells’s treatment of comparative embryolo- that there are no shared features in develop- gy is remarkably limited; for example, he ment at all? That a chicken gets a planula while never discusses invertebrate development. Yet the duck gets a naupius? If so, he needs to there are plenty of shared developmental pat- show it, but Wells never gets to specifics — terns there as well. Despite the very different apparently because the specifics aren’t there. appearance of echinoderm, hemichordate, and Innuendo and accusations of fraud do not cut it chordate embryos, they all share the deuteros- in science. tome condition, in which the first cell opening WHAT TEXTBOOKS SAY becomes the anus, before they diverge to their adult body plans. Or what about the tro- or any textbook to show Haeckel’s chophore larvae of most protostomes and spi- drawings themselves as unqualified ral cleavage shared by annelids, arthropods, Fstatements of developmental anatomy or mollusks (Nielsen, 1995; Fell, 1997)? The to advocate “recapitulation” in a Haeckelian nauplius larvae of crustaceans (Gilbert, 1997) sense would be inexcusable, but none of the or the verliger larvae and development of gas- textbooks reviewed by Wells appear to do so. tropods, which go through flexure, torsion, and Wells gleefully excoriates Futuyma for using degeneration of muscles on one side of the Haeckel’s drawings (Figure 10a), but appar- body, suggestive of their evolutionary history ently in his fit of righteous indignation, he for- (Nielsen, 1995; Collier, 1997)? These are just a few of the specific similarities of the kind that Wells implies do not exist. Similarities in embryonic sequences are data — characters by which we can discover shared similarities among organisms that can be used to recon- struct their relationships. Using such data in phylogeny is not the same as using those char- acters in any “recapitulationist” way. Finally, Wells concludes by attacking prominent biologists such as Gould and Futuyma for supposedly not knowing the truth about Haeckel, saying that this is “a confession of ignorance not likely to inspire confidence in the quality of our biology textbooks” (Wells, Figure 10a. Romanes (1892) embryo draw- 2000:107). Wells’s own misrepresentations of ings reproduced in Futuyma (1998:653). 35 Icons of Evolution? Why Much of What Jonathan Wells Writes about Evolution is Wrong Alan D. Gishlick, National Center for Science Education

Figure 10d. Embryos redrawn and some- what corrected in Raven and Johnson (1999:288). accurate drawings (Miller and Levine, Johnson, Biggs, Kapicka and Lundgren; Figure 10b. Romanes (1892) embryos Figures 10f,g,h); some use photos (Campbell, reproduced and placed in historical con- Reese and Mitchell, Mader; Figures 10i,j); text in Guttman (1999:718) only Starr and Taggart (Figure 10c), Raven and Johnson in their development chapter along got to read the text, in which the drawings are with accurate drawings and photos; (Figure discussed in a historical context — stating 10d), and Schraer and Stolze (but redrawn and why Haeckel is wrong — and Futuyma has an corrected; Figure 10e) use what could be con- entire chapter devoted to development and sidered embryos “redrawn” from Haeckel. No evolution. Guttman (Figure 10b) uses them in textbook discusses embryology in any way an explicitly historical context as well. Wells states that books use “Haeckel’s drawings, or redrawn versions of them” (Wells, 2000:255), but this is not true. Figures 10a–j show Haeckel’s drawings compared to the drawings in the textbooks reviewed by Wells. It can be clearly seen that a majority of the drawings are not “redrawn.” Some textbooks show more

Figure 10c. Romanes (1892) embryos Figure 10e. Embryos redrawn and corrected redrawn in Starr and Taggart (1998:317). in Schraer and Stolze (1999:582)

36 Icons of Evolution? Why Much of What Jonathan Wells Writes about Evolution is Wrong Alan D. Gishlick, National Center for Science Education that could be considered strongly “recapitula- tionist.” In most textbooks, embryology is pre- sented in just one or two paragraphs, making it hard to discuss all the complexities of devel- opment. At a high school level, the aim of the book is to convey some basic concepts of biol- Figure 10h. Embryo drawings in Biggs et al. ogy, not to confuse students with the complex- (1998:433). Identical drawings appear in the ity of a subject. evolution chapter (p.416) of Raven and Johnson (1999).

Figure 10i. Embryo photos in Campbell, Reese, and Mitchell (1999:424).

Figure 10f. Original embryo drawings in Miller and Levine (2000:283).

Figure 10j. Embryo photos in Mader Figure 10g. Original embryo drawings in (1998:298). Johnson (1998:179). 37 Icons of Evolution? Why Much of What Jonathan Wells Writes about Evolution is Wrong Alan D. Gishlick, National Center for Science Education

WELLS’S “WELL-DEVELOPED” more accurate pictures only earns a book a D. GRADING SCHEME In order to earn a C or higher, a book must not he grading scheme employed by Wells use “misleading drawings or photos.” This is designed for failure. This is because amounts to complaining that textbooks should- Wells assumes all drawings to be n’t allow students to be misled by reality! T Wells does not specify what kind of drawings “redrawn” from Haeckel and gives any book with a drawing an F (Figure 11). Wells does or photos would not be misleading. Thus Wells not explain how one would determine whether apparently thinks that all visual presentations they are simply redrawn from Haeckel; in any of embryos are misleading, whether they are case none of the books appear to contain mind- accurate or not. Wasn’t Wells the one com- lessly redrawn figures (Figure 10a–j). Using plaining about selective use of data? He actu-

Figure 11. Wells’s grades for the embryology sections of textbooks.

38 Icons of Evolution? Why Much of What Jonathan Wells Writes about Evolution is Wrong Alan D. Gishlick, National Center for Science Education ally attacks Mader and Campbell, Reese, and WHY WE SHOULD STILL TEACH Mitchell, for using “misleading photos” COMPARATIVE EMBRYOLOGY because they show embryos of a chick and a espite changes in how we view the role human, which he says “just happen” to have a of developmental programs as reflec- stronger resemblance than would embryos Dtions of evolutionary history, we can from any other “classes” of vertebrate. Wells is still see how the same embryonic structures wrong: a chick embryo at that stage looks develop into different adult structures. We much more like an alligator embryo than a observe the unity of developmental plan in all mammal embryo (comparisons made from vertebrates. This is what we see, and no Nelson, 1953, Schaunisland, 1903, and Reese, amount of wishful thinking on the part of evo- 1915). This is in accordance with the predic- lution detractors can change that. There is no tions of evolutionary theory, because an alliga- reason to let their baseless complaints and tor and a chicken share a more recent ancestor character assassination dissuade biology with each other than they do with a mammal, teachers from presenting the evidence to stu- and thus should have more similar a develop- dents. mental program. Wells also chides Mader for HOW TEXTBOOKS COULD IMPROVE saying that embryos “have many features in THEIR PRESENTATIONS OF common” (Wells, 2000:103–104). Does Wells COMPARATIVE EMBRYOLOGY assert that they have no features in common? If extbooks could largely improve the pre- so, he should document it. Having failed to do sentations of embryology by lengthen- this, Wells merely labels anything he does not ing their discussions of it, and by using like “misleading.” Wells also takes exception T photos rather than cartoonish drawings. They to the colloquial term “gill slits,” which is a could also be more explicit about how embry- commonly used non-technical term for pha- onic precursors develop into different adult ryngeal pouches. Wells implies that by using structures. Finally, adding discussions of Hox this term, biologists and textbooks are saying gene complexes (master developmental con- that all animals’ embryos have gills. This is trol genes) and evolutionary developmental patently false. No textbook reviewed even biology would help bring the books up-to-date implies the presence of gills in embryos. The in their treatment of developmental biology. question is what these structures are and what We are learning more about the evolutionary they become, not what they are called. Using history and underpinnings of developmental the terms “gill slits” automatically results in a programs every day. We are learning how C even if the textbook contains no images, and developmental programs are the source of regardless of its content. Campbell, Reese, and much of the evolutionary novelty that natural Mitchell, and Guttman both contain entire selection shaped. Wells ignores all this. To fol- chapters devoted to developmental biology in low Wells’s advice would arrest the develop- which they do discuss some of the “early stage ment of students’ knowledge. differences” that Wells suggests they do not. They receive no credit for these extensive treatments (Figure 11).

39 Icons of Evolution? Why Much of What Jonathan Wells Writes about Evolution is Wrong Alan D. Gishlick, National Center for Science Education

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