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].