Recapitulation Theory: Repackaged & Re-Applied

The rehabilitation of Ernst Haeckel’s image

by Dr. Elizabeth Mitchell on July 31, 2013; last featured August 21, 2020
Featured in Answers in Depth


Do human embryos replay the evolutionary history of their species as they develop? This idea has led many to believe that what is growing in a woman's womb is merely an animal that can be conveniently disposed of in its fish stage. Countless people have been convinced by the wonders of the developing embryo—falsely portrayed—that evolution must be true. Why is this falsified idea still accepted by many teachers and scientists?


Although false representations, Haeckel’s drawings have continued to be presented in textbooks as “proof” of the general theory of evolution and recapitulation in particular.

Do developing embryos really replay the evolutionary history of their species as they develop? Summed up in the catchy statement, “Ontogeny recapitulates phylogeny,” recapitulation theory (also known as the biogenetic law) was popularized by Ernst Haeckel’s nineteenth century illustrations comparing animal and human embryos. Haeckel produced these artistic drawings, supposedly based on his own specimens1 of different embryos, claiming that all of them pass through stages reminiscent of their evolutionary ancestors.

Although false representations, Haeckel’s drawings have continued to be presented in textbooks as “proof” of the general theory of evolution and recapitulation in particular. Evolutionary biologists often acknowledge the inaccuracy of the drawings but continue to regard the recapitulation “theory”2 and its variants as valid. On the strength of its popularity among evolutionary biologists, the idea has gained wide acceptance even in other disciplines such as linguistics and developmental psychology. To many people, the evolutionary principles underlying recapitulation theory are fundamental truths, so the theory retains its authority in their thinking even when it does not fit the observable facts. However, in recent years Haeckel’s evolutionary critics have changed their tactics to try to rehabilitate his reputation as a fraud and to validate his fanciful drawings. Disregarding the “liberties” he took, they paint him as brilliant for manufacturing pictures to prove what he wished were true, though he knew and admitted that it was not.

Far from being abandoned, recapitulation theory persists in the educational system, even in the hands of those who admit that it does not fit the facts. It remains a tool to explain evolutionary dogma to students and to get them to take the theory of evolution for granted. While some dedicated evolutionists debate which variation of the recapitulation theory is best, others claim it is a valid predictor of evolutionary stages and try to unravel the deep evolutionary past shrouded by what they claim is an “incomplete” fossil record. Thus, recapitulation theory continues to fuel the evolutionary thinking of students from the cradle to college, the lay public, and many academic professionals.

Big Words in Recapitulation Theory

“Ontogeny recapitulates phylogeny.” The way that phrase rolls off of the tongue of people trained to say it, when combined with Haeckel’s imaginative drawings, appeals powerfully to the ear, the eye, and the misguided minds of post-modern evolutionists. After all, how could big medical-sounding words that rhyme so nicely be anything but wise and true? But what do those big words mean?

Ontogeny means development from the earliest stages to maturity. In biology, ontogeny is roughly synonymous with an individual organism’s development. Certainly, a fertilized egg must pass through a number of stages as it grows into a mature organism ready for life outside its mother’s womb or its egg. A developing embryo changes its shape dramatically as it morphs into its mature form. Anatomical structures of great complexity seem to begin as much simpler forms. But this apparent simplicity is deceptive. It is only a superficial impression; nevertheless, the illusion of simplicity seems to fit the evolutionary story that comparative embryology supposedly tells.

Embryological development is not at all simple, however. The superficial appearance of some structures (like so-called “gill-slits,” discussed below) leads to false faith in Haeckel’s claims. Additionally, mistaken beliefs about vestigial structures are a product of erroneous recapitulation claims. Some anatomical structures in the developing embryo disappear completely or regress substantially once they serve their developmental purpose, remaining only as scar-like vestiges (literally, “footprints”) in the mature human. An example would be the median umbilical ligament, a fibrous remnant between the top of the bladder and the “belly-button,” marking a structure important during the formation of the urinary bladder. This ligament is a “footprint” of the developmental process, not of evolutionary ancestry. For many other complex, well-formed anatomical structures—like the appendix, the thymus, or the pineal gland—the function was not obvious to early anatomists. This led to the false notion that they had no function and were vestiges of evolution. Vestigial organs are commonly (but falsely) viewed as “useless” anatomical structures leftover from an evolutionary past. In reality there are no useless organs, unless because of injury or loss, and every structure so falsely “accused” has an important function in the embryo, the mature human, or both.

Phylogeny refers to evolutionary ancestry. It is based on the presumption that all living organisms evolved from simpler forms through natural processes. The phylogenetic tree of life is a metaphor for the branching of the earliest life forms, which, developing additional complexity, diverged into more and more branches, eventually leading—according to the orthodox tale—to the many distinct life forms we see today. Keeping with the idea that things start out simple and become complex, Haeckel, like many evolutionists then and now, maintained that all animal life can be traced back to a single common ancestor, that phylogeny is monophyletic.

Recapitulation means repeating or summarizing something. Thus, saying that “ontogeny recapitulates phylogeny” means that embryonic development consists of stages that repeat, at least structurally, the various animals on that organism’s supposed ancestral trip up the tree of life. Haeckel claimed that the sequential stages of an embryo repeat the forms of the adult organisms in its hypothetical evolutionary past. Because observation shows that developing embryos do not resemble the adults on any proposed evolutionary tree of life, a modified form of the theory holds that an embryo only resembles the embryos of its evolutionary ancestors, not the adults. A more radical and still more recent retrofitting of Haeckel’s claims maintains that he intended recapitulation theory to apply only to individual traits, rather than to entire embryonic stages.3

Seen and Unseen in Recapitulation Theory

Ontogeny is observable. Embryonic development of an organism can be studied in detail. Presently, with technologies that enable us to see the developing embryo from fertilization forward, each stage of human embryonic development and of many animals has been examined videographically in high fidelity moving pictures. Holographic moving 3D images are now also feasible. When Haeckel’s static drawings were published, they purportedly showed a comparison of the embryos of a number of vertebrates. In his own time, some saw Haeckel’s illustrations as fraudulent. Others say he took artistic liberties to emphasize a point. Regardless, the images were almost immediately shown to falsify the facts of embryonic development.

Phylogeny, by contrast with ontogeny, is not observable. No amount of scientific achievement makes it possible to see back through time to observe the fictional upward evolution of life. Neither does biological research reveal any mechanism by which a simpler kind of organism can acquire the genetic information to become a more complex kind of organism. No such transformation has ever been observed because none has ever occurred. Fossils labeled “transitional forms” are actually just animals with a variety of characteristics interpreted through an evolutionary imagination that proposes links that never existed at any time.

Thus, phylogeny is a figment; it’s propaganda, invented to try to explain life without God. It fails. The claim that “ontogeny recapitulates phylogeny” is false. Because it is false, it does not fit the fossil record and is inconsistent with any logic. Complex organisms cannot develop by accident any more than the words on this page could accidentally be formed from random arrangements of letters. But because “evolution” is presented to students and to the public as indisputable fact, supported by many who have believed the propaganda, recapitulation theory remains a tool for education, a visually appealing bit of manufactured evidence, and a paleontological mythology supposedly enabling evolutionists to put fossils into the “right” evolutionary lineages.

History of Recapitulation Theory

Haeckel’s famous (infamous) set of 24 drawings

Haeckel’s famous (infamous) set of 24 drawings purporting to show eight different embryos in three stages of development, as published by him in Anthropogenie, in Germany, 1874. This is the version of his drawings most often reproduced in textbooks. Left to right are shown embryos of a fish, salamander, turtle, chicken, pig, cow, rabbit, and human. Top to bottom depicts three stages of development. The drawings contain errors intended to emphasize embryonic similarity and support recapitulation theory. IMAGE by M. Richardson and G. Keuck, via Biological Reviews of the Cambridge Philosophical Society.4

While Haeckel’s drawings are the best and most familiar expression of recapitulation theory taught to modern schoolchildren, college students, and adults, the idea did not originate with Haeckel or Darwin. The germ of recapitulation theory is found in the ancient world, and in the nineteenth century it appears in the writings of J. F. Meckel (1811), Karl Ernst von Baer (1828), Charles Darwin (1859), and finally Ernst Haeckel (1866).

Haeckel was a professor of zoology in Germany. He was particularly moved by Darwin’s Origin of Species, and actively promoted Darwinian evolution to the public and to academia. As he taught how humans gradually developed through upward evolution along a tree of life, he presented hypothetical simple organisms as if they were real, an ape-man for which he had no evidence, and his infamous doctored embryo sketches.

Haeckel’s version of the “biogenetic law” held that embryos looked like the adult forms of their evolutionary forebears. He wrote that embryonic development paralleled phylogenetic (evolutionary) history—that “embryonic development is a short and rapid re-run, or recapitulation, of evolution.”5 To support his claim, in his book Natürliche Schöpfungs-geschichte (Germany, 1868; published in English in 1876 as The History of Creation), Haeckel included sketches of embryos substantially altered to make his point. “His drawings are also highly inaccurate, exaggerating the similarities among embryos, while failing to show the differences,” explains embryologist Michael Richardson, lead author of a famous 1997 article refuting Haeckel’s claims.6

Soon after publication, Haeckel’s nineteenth century contemporaries spotted the fraud and publicized it. For instance, in 1874, William His, after critiquing Haeckel’s ideas and demonstrating that many of the embryo figures were “invented,” concluded, “The procedure of Professor Haeckel remains an irresponsible playing with the facts even more dangerous than the playing with words criticized earlier.”7

For over a century, criticism from the evolutionary scientific community has continued. “Scientific objections to Haeckel’s drawings . . . include charges of:

  1. doctoring (the alteration of images during copying);
  2. fabrication (the invention of features not observed in nature); and
  3. selectivity (the use of a misleading phylogenetic sample).”8
  4. The most generous and gracious modern assessments have been unable to allay charges of falsification, and Haeckel even admitted to some of the accusations. For instance, to the charge that he printed a woodcut of a single turtle embryo three times, altered to represent three different species, he confessed to “an imprudent folly” necessitated by a shortage of time.9

    Despite the almost immediate rejection of Haeckel’s evidence by much of the scientific community, his rather impressive fabrications found their way into textbooks where they still appear as a modern proof that propaganda can sometimes pass for truth. Countless children and adults—and young women coaxed to proceed with abortion—have been told that the human embryo goes through a fish stage, an amphibian stage, and a reptilian stage. Attesting to the sometimes-disputed fact that these fraudulent “teaching tools” persisted in the educational system despite their known errors and general rejection in the scientific community, evolutionist Stephen Gould in the year 2000 wrote:

    Haeckel had 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. At certain stages in early development, vertebrate embryos do look more alike, at least in gross anatomical features easily observed with the human eye, than do the adult tortoises, chickens, cows, and humans that will develop from them. But these early embryos also differ far more substantially, one from the other, than Haeckel's figures show. Moreover, Haeckel's drawings never fooled expert embryologists, who recognized his fudgings right from the start.

    At this point, a relatively straightforward factual story, blessed with a simple moral story as well, becomes considerably more complex, given the foils and practices of the oddest primate of all. Haeckel's drawings, despite their noted inaccuracies, entered into the most impenetrable and permanent of all quasi-scientific literatures: standard student textbooks of biology. . . . We should therefore not be surprised that Haeckel's drawings entered nineteenth-century textbooks. But we do, I think, have the right 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!10

    In a succinct summation of Haeckel’s work, Gould concluded that Haeckel, who used his doctored diagrams as data to support his scientific hypotheses, committed the “academic equivalent of murder.”11 (The popular use of Haekel’s work to support abortion is far worse, making it not the “academic” but the moral equivalent of murder.)

    A 1997 study of comparative embryology, published in the journal Anatomy and Embryology by embryologist Michael Richardson, then of London’s St. George’s Hospital Medical School, also called attention to the persistent acceptance of Haeckel’s fraudulent diagrams. He found that Haeckel had resized embryos and eliminated limb buds and heart bulges to enhance similarity. He wrote, “These drawings are still widely reproduced in textbooks and review articles, and continue to exert a significant influence on the development of ideas in this field.”12 Gould quotes Richardson saying, “I know of at least fifty recent biology textbooks which use the drawings uncritically.”13

    While some excuse Haeckel’s diagrams as mere schematics, these “schematics” were clearly meant to systematically and deceptively alter the facts. For instance, he selectively removed limbs on one of his embryos while rendering others perfectly, commenting that they were similar with “no trace of limbs or ‘extremities’ in this stage.”14 According to Richardson, the “intent [of these systematic alterations] is to make the young embryos look more alike than they do in real life.”15 The alterations, as Haeckel admitted, were deliberate, and he knew they were falsifications of the facts.

    Despite overwhelming evidence refuting Haeckel’s claims and the manufactured data he used to support them, Richardson and colleagues write, “The idea of a phylogenetically conserved stage has regained popularity in recent years.”16 To assess the merits of recapitulation theory and Haeckel’s work, they conducted a systematic examination of embryos from all sorts of vertebrates, noting that modern textbooks typically confine their attention to the frog, the chick, and the “typical” mammal. They compared the most phylotypic stage of each—the stage at which vertebrate embryos possess comparable characteristics such as a notochord, pharyngeal arches (“gill slits”), a neural tube, somites (segments of undifferentiated blocks of embryonic mesoderm), and a postanal tail (a posterior extension of the embryo’s developing musculoskeletal structures beyond the anus). Richardson et al. in 1997 confirmed that even the earliest stages of embryonic development vary greatly between vertebrate species. They attributed these differences to evolution, as they hold an evolutionary worldview. But their paper demonstrated, on the basis of rigorous comparative embryology, that the “biogenetic law” as commonly understood is false.17

    A quick internet search today will produce many references to recapitulation theory as “inadmissibly simplified,”18 “outdated” and “buried,”19 “refuted,” “defunct” and “largely discredited.” Haeckel’s drawings are recognized by many as “fraudulently modified”20 “misinformation.”21 Embryologist Michael Richardson was quoted in a 1997 issue of Science magazine saying Haeckel’s work was “turning out to be one of the most famous fakes in biology.”22 So has Haeckel’s work—so heavily criticized even in the evolutionary community—dropped off the scene? No. Why is that?

    Despite over a century of widespread acknowledgment that Haeckel faked his pictures, Haeckel’s claims and even colorized adaptations of his diagrams still show up in the popular press and even textbooks. For instance, the cover story of Time magazine (November 11, 2002) reported that the human embryo at 40 days “looks no different from that of a pig, chick or elephant. All have a tail, a yolk sac,23 and rudimentary gills.”24 Even twenty-first-century textbooks perpetuate this nineteenth-century fraud. Sylvia Mader’s 2010 edition of Biology, for instance, features colorized Haeckel-ish embryos and teaches, “At these comparable developmental stages, vertebrate embryos have many features in common which suggests they evolved from a common ancestor.”25

    In a world where evolutionary educators decry any effort to “teach the controversy” in public schools—allowing students to be exposed to facts that reveal problems with evolutionary dogma—the convenient foot-dragging on the removal of this compelling lie from curricula is telling.

    Those Fishy Gill Slits in Recapitulation Theory

    Our embryonic “gill slits” are possibly the most often-cited anatomical “proof” of our fishy ancestry. Inside the Human Body, a popular 2011 BBC1 program hosted by Dr. Michael Mosley, provides a typical example. The program features a state-of-the-art high-quality video of human embryonic development called “Anatomical clues to human evolution from fish.”26 The video was produced by digitally splicing scans taken in early pregnancy. Mosley interprets the developing features as anatomical proof of fish in our evolutionary past. Among these are “gill-like structures,” a reference to the “gill slits.”

    The poorly named “gill slits” in human embryos are not anything at all like gills and are not even slits, just folds of tissue destined to develop into various anatomical parts of the head and neck. They never have a function or a structure remotely resembling gills. They don’t even turn into anything having to do with the lungs. Never in the course of development does a human embryo absorb oxygen from water as fish do with gills.

    Evolutionist Steven Jay Gould writes, “in Haeckel’s evolutionary reading, the human gills slits are (literally) the adult features of an ancestor” (emphasis in original).27 In later writings, Haeckel did not ascribe a respiratory function to these structures in the non-fish embryo. He still maintained that there were actual gill slits and gill arches in the non-fish embryos but that they had evolved into other structures. He wrote in 1892 that “we never meet with a Reptile, Bird or Mammal which at any period of actual life breathes through gills, and the gill-arches and openings which do exist in the embryos are, during the course of their ontogeny, changed into entirely different structures, viz. into parts of the jaw-apparatus and the organ of hearing.”28 And by 1903 he wrote of the “total loss of respiratory gills,” saying that “in the embryos of amniotes there is never even a trace of gill lamellae, of real respiratory organs, on the gill arches.”29

    Evolutionists consider homologies in fish gills, fish jaws, reptilian jaws, and mammalian ear bones to be sequential evolutionary developments that demonstrate the common evolutionary ancestry of fish, reptiles, and mammals. Homologous structures are the different anatomical structures that form from a similar embryonic structure. Meckel’s cartilage, for instance, has different destinies in different creatures. Meckel’s cartilage supports the gills in cartilaginous fish. It ossifies to form the jaws of bony fish and reptiles. And in mammalian embryos, Meckel’s cartilage helps shape the middle ear bones and the mandible; then it virtually disappears. But each creature has its own kind of DNA directing the process through complex and as-yet incompletely understood mechanisms. At no time in science do we see DNA of one creature mutating to produce new information that can change the organism into a new kind. And at no point do these so-called mammalian “gill slits” have anything to do with gills or respiratory structures.

    Mammalian “gill slits” are folds in the region of the tiny embryo’s throat. By the 28th day of life, the embryo’s brain and spinal cord seem to be racing ahead of the rest of the body in growth. Therefore, for a time, the spinal cord is actually longer than the body, forcing the body to curl and flexing the neck area forward. (This curled embryo with the long spinal cord is mistakenly accused by some people of having an animal’s tail.) Just as many people develop a double chin when bending the neck forward, so the embryo has folds in its neck area due to this flexing.

    Gill slits, thus, is a misleading name, since these folds are neither gills nor slits. Another popular name, branchial arches, is just as deceptive because branchial comes from the Greek word for “gills.” Somehow the name neck folds just isn’t fancy enough for our scientific minds, so these folds are called pharyngeal arches, since they are arch-shaped folds near the throat. (Pharyngeal is the scientific word for things having to do with the throat. When you say you have a sore throat, your doctor says you have pharyngitis.) The creases between the folds are called pharyngeal clefts, and the undersides of the folds are called pharyngeal pouches. The pouches and clefts are not connected by an opening. Each fold shapes itself into specific structures, none of which are ever used for breathing. The outer and middle ear as well as the bones, muscles, nerves, and glands of the jaw and neck and even the immune system’s thymus gland develop from these folds as tissues differentiate in compliance with human DNA.

    Only superficially and at the most simplistic level do these important folds ever resemble gills. Some embryology textbooks have adopted non-deceptive terminology. For instance, Langman’s Medical Embryology explains:

    The pouches penetrate the surrounding mesenchyme, but do not establish an open communication with the external clefts. Hence, although development of pharyngeal arches, clefts, and pouches resembles formation of gills in fishes and amphibians, in the human embryo, real gills (branchia) are never formed. Therefore, the term pharyngeal (arches, clefts, and pouches) has been adopted for the human embryo.30

    Nevertheless, the meaning-packed terms gill slits and gill-like structures persist. But mammalian pharyngeal arches are no more related to gills—ancestrally or otherwise—than stars are to streetlights.

    Even texts that refer to these folds by correct names sometimes perpetuate the powerful gill slit myth. For instance, Mader’s Biology (2007 edition) correctly describes the ultimate anatomic destiny of each pharyngeal arch component and then asks:

    Why should terrestrial vertebrates develop and then modify such structures like pharyngeal pouches that have lost their original function? The most likely explanation is that fishes are ancestral to other vertebrate groups.31

    What “lost original function”? No one has ever documented that pharyngeal pouches in the embryos of terrestrial vertebrates function as gills or that adult terrestrial vertebrates ever had gills. Preserved in textbooks and the media, the fishy ancestral myth persists. Our unseen and unverified fishy past still surfaces regularly in the assumptions that the pouches/folds/slits, or whatever-they-get-called, are leftovers from a fish ancestor.

    In a chilling application of this misinformation, many abortionists have used Haeckel’s embryologic falsehoods to assuage the guilt of women seeking abortion, telling them they’re only removing something like a fish, not a baby. The late Dr. Henry Morris observed, “We can justifiably charge this evolutionary nonsense of recapitulation with responsibility for the slaughter of millions of helpless, pre-natal children—or at least for giving it a pseudo-scientific rationale.”32

    The Current Debate about Recapitulation Theory

    Given all the data refuting recapitulation theory, do any real scientists still cling to its discredited notions? After all, it’s one thing to foist a fabricated over-simplified bit of evolutionary evidence on the gullible public and generations of children and college students, but do professionals hang on to these notions, too?

    While some professional evolutionary scientists have given up on recapitulation theory altogether, many continue to cling to various permutations of it.

    Some try to distance the beloved recapitulation dogma from Haeckel and go back further to Karl Van Baer in 1828 who claimed that observable embryonic stages only recapitulate the embryonic stages of their evolutionary ancestors. Neither version is true, however. And as Richardson’s work has demonstrated, vertebrate embryos have discernible differences even at the earliest stages, an observation that finally strips the supposed underpinnings of both versions. Thus to try to salvage the false theory, some evolutionary biologists have cherry-picked the parts they think they can make the best case for.

    Ernst Mayr’s modification, laid out in “Recapitulation reinterpreted: the somatic program,” appeared in 1994 in the Quarterly Review of Biology. He wrote that despite “the disrepute into which Haeckel’s claims had fallen . . . every embryologist knew that there was a valid aspect to the claim of recapitulation.”33 A 2012 paper coauthored by Richard Lenski, “Ontogeny Tends to Recapitulate Phylogeny in Digital Organisms,” notes that Mayr’s “sentiment is still widely held today, and the idea that ontogeny recapitulates phylogeny in some form has its modern proponents.”34

    Forcing the Facts to Fit the Recaptiulation Theory

    Recapitulation theory is just too appealing to abandon for many evolutionists. Lenski’s group wrote, “At a minimum, the fact that the debate has continued for so long lends credence to Mayr’s view that there is at least some validity to recapitulation.”35

    Perhaps the most dramatic rehabilitation of Haeckel has come at the hands of one of his best-known modern critics, Michael Richardson. In the 2002 paper “Haeckel’s ABC of Evolution and Development” published in Biological Reviews of the Cambridge Philosophical Society, Richardson and Gerhard Keuck re-examined Haeckel’s work. They wrote:

    Haeckel recognized the evolutionary diversity in early embryonic stages, in line with modern thinking. He did not necessarily advocate the strict form of recapitulation and terminal addition commonly attributed to him. Haeckel's much-criticized embryo drawings are important as phylogenetic hypotheses, teaching aids, and evidence for evolution. While some criticisms of the drawings are legitimate, others are more tendentious. . . . Despite his obvious flaws, Haeckel can be seen as the father of a sequence-based phylogenetic embryology.36

    Richardson and Keuck conclude that the biogenetic law is valid after all, if applied to the evolution of “single characters only” and not entire embryonic and evolutionary stages.37 In other words, so long as only single traits are followed through evolutionary time and embryonic development, Richardson is now aboard the recapitulation bandwagon.

    Richardson and Keuck’s analysis of Haeckel’s work was not able to expunge the charge of falsification, but they clearly have granted moral immunity for his falsehoods. They and others support “Haeckel’s practice of filling in gaps in the embryonic series by speculation”38 even though “Haeckel presented the embryo drawing as data in support of his hypotheses”39 and not just helpful teaching aids.

    He created a fictional version of “reality” and foisted it off onto generations then yet unborn.

    Haeckel’s artistic liberties are clearly not the result of any lack of observation skills or artistic ability. One of his latter-day apologists has even praised Haeckel’s diagrams of single-celled radiolarians, noting their resemblance to modern light microscope images and electron micrographs.40 Haeckel was a skilled illustrator able to render what he observed with accuracy and detail when he wanted to. But when real observation failed to confirm what he wanted to find in order to support his preferences about the past and its parallels in the present, he modified the facts instead of the theory. He created a fictional version of “reality” and foisted it off onto generations then yet unborn.

    The ultimate excuse for Haeckel’s graphic concoctions has come from those who wish to honor what they see as his cognitively pure prescience coupled with a somewhat liberal view of the purpose of scientific illustration. “Haeckel’s own views on art stressed the primacy of interpretation over pure observation,”41 Richardson and Keuck write. They note that Haeckel’s own writings reveal that he knew early embryos of various species have a lot of differences. They assert that Haeckel therefore never intended for his pictures to depict his actual observations but rather to show what he deemed to be “a true reproduction of the really existing natural produce.”42 And though some of these drawings clearly were fabrications, Haeckel intended them as support for his recapitulation theory. Yet because the authors of the study maintain that recapitulation theory is true so long as it is viewed in a certain way—one trait at a time, with allowances for traits that have disappeared over time—they believe “Haeckel’s embryo drawings are important as phylogenetic hypotheses, teaching aids–even scientific evidence” (emphasis ours).43

    Despite naysayers, “current consensus seems to be that recapitulation is a general trend of evolution, at least in the form of terminal addition being the most common way that new traits are added to ontogenies.”44 Terminal addition is Stephen Jay Gould’s idea that each evolutionary development built on the previous ones, though the duration of earlier stages decreased, the telescopically shortened early stages continuing to be represented in embryologic stages. This represents one of the modifications in vogue for salvaging Haeckel’s work.

    But Why?

    What recapitulation believers still struggle with, however, is some reason recapitulation should be true. What evolutionary advantage would it have? If embryos really recapitulate their evolutionary past, what is the evolutionary advantage of anatomic structures that develop and ultimately don’t get used? Why would unused “gill slits,” for instance, stick around across the vast evolutionary timescale through organisms that did not need gills until they could evolve a non-respiratory purpose some millions of years later? Some embryologic scaffolding structures only serve temporary purposes and then are sloughed off, restructured, or are disassembled entirely. But they are essential functional systems such as the amniotic sac, the placenta, and the umbilical cord. If these represent footprints of an evolutionary past, why would structures that don’t get used in the mature organism persist purposelessly through millions of years of evolutionary history?

    In an attempt to answer this question, some expand on Gould’s idea of “terminal addition,” proposing that successful earlier evolutionary innovations are not lost but allowed to keep functioning while new developments are added. To undo earlier developments before they have served their place-holding purpose in the newly evolving organism would disrupt subsequent add-ons. Earlier evolutionary stages must be conserved in the embryo, at least for a time, because “evolution is not only restricted to ‘tinkering’ with pre-existing ontogenies, but must do so ‘while the engine is running’ [that is, while the organism is still alive]. Most additions will occur at the end of ontogeny,” thus minimizing interference with later developments.45

    The presumption is that the stepwise addition of successful evolutionary steps over millions of years is reflected in the constraints upon embryonic development, but compressed down to a matter of days or weeks. Stepwise modification of many structures occurs in an embryo whose development is directed by its DNA, but how can mindless random evolution “know” it needs to keep a useless structure in place for millions of years?

    Evolution of complex new kinds of animals would require some way to build complex traits. Lenski’s group suggests recapitulation supplied this need. “Complex traits are often built upon and may even require the prior existence of simpler traits,” they explain. “Complexity may thus increase during both evolution and development, thereby generating a correlation in the ordering of events across these distinct timescales that reflects that dependency.”46 This idea of course presumes that the superficial appearance of morphological simplicity in an embryo—a tube, for instance—embodies no particularly significant unseen complexities. For evolutionary purposes, it is more convenient to ignore those subtleties.

    Lenski’s group, admitting the difficulty in testing the validity of recapitulation theory in living organisms, decided in their 2012 study to seek the truth in the virtual world. They designed self-replicating computer programs to “mutate, compete for resources, and evolve, mimicking natural selection in real-life organisms.” Like a developing embryo, the computer simulation followed a logical stepwise process to increase complexity, with only those rare “mutations” that were neither detrimental nor inconsequential surviving and increasing the apparent complexity of the virtual organisms. Lenski’s group concluded from their computer simulation that ontogeny does indeed recapitulate phylogeny.

    Lenski’s computer simulation did not actually mimic the upward evolution of complexity, however. Biological recapitulation demands embryos re-enact upward evolution through distinct kinds, like a fish stage, amphibian stage, and so forth, up to mammals. But the computer programs replicating themselves in Lenski’s computer simulation merely reshuffled and tweaked the information they were provided with from the beginning. They did not acquire the information from their mutations to become something more than computer programs, just computer programs that did what their available tools made possible in the first place. They imitated variation and natural selection, not phylogeny.

    Step By Embryonic Step

    Because embryonic development reveals a proven stepwise way for countless anatomical features to develop, it provides a sort of a wish list for evolutionists needing to explain how complex features could develop. After all, if a creature more or less matching each stage in a complex process could be found, a plausible evolutionary sequence could be created—assuming of course that some way to make the evolutionary transition actually existed.

    Embryonic development shows that some structures form to sustain or guide or induce the formation of other structures. Examples include the notochord (which acts as a template for cells that develop into vertebrae), the urachus (which is involved in formation of the bladder), and most of Meckel’s cartilage. Evolutionists often claim some of these structures are the evolutionary “memories” of previous ancestors, but in reality they are just the templates, scaffolds, and regulators to allow more functional structures to be built. When their purpose is served, the scaffolds may be reabsorbed, disappearing entirely (like the notochord), or remain as scars or so-called vestigial structures (like the urachus, a fibrous remnant). (Vestigial means “footprint” and as such is a record of embryologic development, not a record of an evolutionary past.)

    Phylogeny And The Return Of Haeckel

    Haeckel’s diagrams do not represent observable embryologic reality, and Haeckel knew that they didn’t when he made them. And he intended them—doctored though they were—to be data in support of his evolutionary ideas. He intentionally falsified the facts in order to use “embryonic resemblance as proof of evolution”47 and “recapitulation as proof of the Biogenetic Law.”48 Yet he receives praise for his insight into the evolutionary past and ability to reconstruct the observable present to represent what evolutionists claim about it.

    Rigorous comparative embryology confirms “there is no evidence from vertebrates that entire stages are recapitulated.”49 Thus, Haeckel’s claims about embryonic development are not supported by any actual facts. Even if embryonic development did proceed as he claimed, of course, it would not prove anything about a hypothetical evolutionary past. But that aside, why are evolutionary scientists and educators so keen to use inaccurate diagrams for “phylogenetic hypotheses, teaching aids, and evidence for evolution”? Why do Haeckel’s modern apologists strain at his work, re-packaging it to show how it would be true if only it were viewed a certain way? For instance, they may pick just one trait at a time while ignoring all others.

    Actual embryonic development, because it succeeds in producing fully functional, mature organisms, tells scientists what to look for, but because whole organisms don’t often meet the demands of the evolutionary story, they try to justify it by tracing single traits through deep time and seeking parallels in actual embryonic development. A fossil that seems to possess a trait in any of the ways it appears in the embryological developmental sequence can be claimed as a representative of an evolutionary sequence and can be assigned a presumed place in the fictional history.

    If any fossils seeming to fit the stepwise nature of different embryological stages can be found, they are lined up as supposed evidence for evolution. In the sciences this is what is called “pseudoscience” because the facts are modified to fit the theory rather than adjusting the theory to fit the facts. But no fossils demonstrate evolutionary transitions. Neither do embryologic stages. Yet by claiming that both actually do represent evolutionary sequences, evolutionists obtain visually compelling propaganda and tie it together through a comforting knot of circular reasoning. Their pseudoscience works as propaganda because it resembles real science. It works in the same way that an effective lie works: by resembling the truth about whatever facts may be represented in the lie, the falsehood gains acceptance—like weeds posing as wheat.

    The controversy about the evolutionary origin of the turtle shell illustrates both of these points. How did the turtle shell originate? Until recently all the turtle fossils found had been fully equipped with modern-appearing shells. Therefore, evolutionists debated whether the shell evolved over millions of years in the sequence seen inside the turtle egg or whether it evolved as a modification of external scales—like those of certain fish. Now that two varieties of turtle with seemingly less-developed parts of the shell have been identified, evolutionary researchers have noted that these shell variations more or less mirror shell developmental stages in the embryo. They therefore are asserting that turtle embryology predicted those forms successfully, showing on the one hand that those soft-shelled turtles are genuine transitional forms and on the other hand that the ontogeny of turtle shells really does recapitulate their phylogeny.

    In reality, what these turtle fossils reveal is not a series of non-turtles evolving into turtles but just varieties of turtles. Mutations alter genetic information, and it is likely that these two extinct turtles are merely variations that developed from the original turtles God created about 6,000 years ago.

    Finally, as teaching aids, teachers and textbook manufacturers can now once again return in good conscience to teaching the mantra, “ontogeny recapitulates phylogeny,” that is—those that ever actually stopped in the first place. In fact, the Next Generation Science Standards now in use in twenty U.S. states reflect generalized acceptance of the concept of recapitulation. For example, the Middle School core idea LS4.A Evidence of Common Ancestry and Diversity states, “Comparison of the embryological development of different species also reveals similarities that show relationships not evident in the fully-formed anatomy.”50 For many who accept evolution as unquestioned fact, any evidence that can be used to indoctrinate the young or the gullible is acceptable, even fraudulent concoctions from a man who was in the habit of manufacturing whatever counterfeits and forgeries he needed in order to promote evolution with the evangelistic zeal of a missionary.

    Thus, despite their inaccuracies, Haeckel’s sometime critic-turned-defender concludes, “Haeckel’s embryo drawings are important as phylogenetic hypotheses, teaching aids—even scientific evidence. . . . The drawings illustrate embryonic similarity, recapitulation, and phenotypic divergence.”51

    The Future Of Recaptiulation Theory’s Falsified Backward Look

    These controversies can be expected to continue, not because there is proof that all life evolved from simpler ancestral forms, but because there is a popular widespread worldview-based belief in molecules-to-man evolution. Believing that life must be explained as the product of natural evolutionary processes, evolutionary scientists struggle to concoct natural explanations wherever they can. Yet embryonic development is observable, and evolutionary phylogeny is not. Their supposed parallelism and the notion that such parallelism would constitute evolutionary proof are popular and powerful lies.

    The observable wonders of embryology—surely a showcase of God’s design—were hijacked by Haeckel and continue to be much too valuable components of the evolutionary toolkit to relinquish. Recapitulation has therefore been resurrected and repackaged to teach and to convince. Haeckel’s “liberties” are excused with a nod that would never be extended to any modern scientist who faked his findings. Recapitulation theory will doubtless continue to fill a prominent place in classrooms and on television documentaries aimed at selling the evolutionary propaganda to the public. Moreover, as illustrated by the case of the turtle shell, highly trained evolutionary scientists who simply assume all things came about through evolution leap ahead of logic: instead of asking “whether” life evolved they simply ask “how” it happened. They will find this supposedly rehabilitated rejuvenated recapitulation theory a convenient tool providing the circular reasoning to justify their prior leap of faith in nothing but millions of years of accidents and death leading to the present moment.

Answers in Depth

2013 Volume 8


  1. Modern evolutionists, like Haeckel’s contemporaries, still debate the actual sources of Haeckel’s diagrams. “However, he did claim in Haeckel (1874a) [Anthropogenie oder Entwickelungsgeschichte des Menschen ] to have his own specimens,” according to Richardson and Keuck. M. Richardson and G. Keuck, “Haeckel’s ABC of Evolution and Development,” Biological Reviews of the Cambridge Philosophical Society 77, no. 4 (2002): 495–528.
  2. A “theory” in science should be strongly supported by observable evidence, and a scientific “law” should have no exceptions. In light of this, recapitulation is more like a failed hypothesis since it has so much against it and no actual experimental evidence in its favor. But since this is the recognized terminology, we will continue to refer to “recapitulation theory,” also known as “biogenetic law,” in this article for the sake of understanding.
  3. M. Richardson and G. Keuck, “Haeckel’s ABC of Evolution and Development,” Biological Reviews of the Cambridge Philosophical Society 77, no. 4 (2002): 495–528.
  4. Richardson and Keuck, “Haeckel’s ABC of Evolution and Development.”
  5. Ibid.
  6. M. Richardson et al., “There Is No Highly Conserved Embryonic Stage in the Vertebrates: Implications for Current Theories of Evolution and Development,” Anatomy and Embryology 196 no. 2 (1997): 91–106.
  7. Richardson and Keuck, “Haeckel’s ABC of Evolution and Development.”
  8. Ibid.
  9. Ibid.
  10. Stephen Jay Gould, “Abscheulich!(Atrocious!),” Natural History 109 no. 2 (2000): 44–45. Quoted in Casey Luskin, “Revisiting Those Pesky Embryo Drawings,”, June 17, 2010.
  11. Richardson and Keuck, “Haeckel’s ABC of Evolution and Development.”
  12. Ibid.
  13. Richardson et al., “There Is No Highly Conserved Embryonic Stage in the Vertebrates.”
  14. Ernst Haeckel, Anthropogenie oder Entwickelungsgeschichte des Menschen. Keimes- und Stammesgeschichte (Leipzig, Germany: Engelmann, 1903); quoted in Michael Richardson and Gerhard Keuck, “A question of intent: when is a ‘schematic’ illustration a fraud?” Nature 410, no. 144 (2001).
  15. Gould, “Abscheulich!(Atrocious!).”
  16. Richardson and Keuck, “Haeckel’s ABC of Evolution and Development.”
  17. Ibid.
  18. “Haeckel’s Recapitulation Theory,” Frozen Evolution,
  19. “G. Stanley Hall (1844–1924),”,
  20. “Haeckel’s Fraudulent Embryo Drawings,”,
  21. “Recapitulation Theory,” Wikipedia,
  22. E. Pennisi, “Haeckel’s embryos: fraud rediscovered,” Science 277 (1997): 1435. Quoted in not proven.pdf.
  23. Just as “gill slits” in human embryos have nothing to do with respiratory functions or gills at any point in development, neither does the so-called human embryo’s “yolk sac” have a nutritional function as a chicken’s yolk sac does. The human embryo’s yolk sac makes the developing baby’s first blood cells and blood vessels. A portion of the yolk sac is even incorporated into structures that form a temporary portion of the urinary collection system, although it does not actually collect any fluid. Within a month the yolk sac’s job is finished, and it remains only as a tiny remnant sandwiched in the placental membranes. But the yolk sac of a human embryo never provides the embryo with nutrition; nutrition is derived from the baby’s mother. A superficial resemblance to a bird’s yolk sac is no evidence of evolutionary lineage or a recapitulated ancestral history.
  24. J. Madeleine Nash, “What Scientists Know About the First Nine Months,” TIME, November 11, 2002,,9171,1003653,00.html.
  25. Casey Luskin, “Current Textbooks Misuse Embryology to Argue for Evolution,” Evolution News Views, June 18, 2010,
  26. Available online at
  27. Stephen Jay Gould, Ontogeny and Phylogeny (Cambridge, Massachusetts: Belknap Press, 1977), 7.
  28. Ernst Haeckel, The History of Creation [translation of the 8th German Edition of Natürliche Schöpfungsgeschichte], ed. E. R. Lankester (London: Kegan Paul, 1892). Quoted in M. Richardson and G. Keuck, “Haeckel’s ABC of Evolution and Development,” Biological Reviews of the Cambridge Philosophical Society 77, no. 4 (2002): 495–528.
  29. Ernst Haeckel, Anthropogenie oder Entwickelungsgeschichte des Menschen; Quoted in M. Richardson and G. Keuck, “Haeckel’s ABC of Evolution and Development,” Biological Reviews of the Cambridge Philosophical Society 77, no. 4 (2002): 495–528.
  30. T. W. Sadler, Langman’s Medical Embryology, 11th edition (Philadelphia: Lippincott Williams & Wilkins, 2010), 265.
  31. Sylvia Mader, Biology, 9th ed. (New York: McGraw-Hill, 2007), 97.
  32. Henry Morris, The Long War Against God (Ada, Michigan: Baker Book House, 1989), 139.
  33. Ernst Mayr, “Recapitulation reinterpreted: the somatic program,” Quarterly Review of Biology 69, no. 2 (June 1994): 223–232.
  34. J. Clune et al., “Ontogeny Tends to Recapitulate Phylogeny in Digital Organisms,” The American Naturalist 180, no. 3 (2012): E54–E63.
  35. Mayr, “Recapitulation Reinterpreted.”
  36. Richardson and Keuck, “Haeckel’s ABC of Evolution and Development.”
  37. Ibid.
  38. Ibid.
  39. Richardson and Keuck, “Haeckel’s ABC of Evolution and Development.”
  40. Ibid.
  41. Ibid.
  42. Ernst Haeckel, Kunstformen der Natur (Leipzig and Wien, Germany: Bibliographisches Institut, 1904); quoted in M. Richardson and G. Keuck, “Haeckel’s ABC of Evolution and Development,” Biological Reviews of the Cambridge Philosophical Society 77, no. 4 (2002): 495–528.
  43. Richardson and Keuck, “Haeckel’s ABC of Evolution and Development.”
  44. Mayr, “Recapitulation Reinterpreted.”
  45. McKinney, M. L., and K. McNamara. Heterochrony: the evolution of ontogeny. (New York: Plenum, 1991). Quoted in J. Clune et al., “Ontogeny Tends to Recapitulate Phylogeny in Digital Organisms,” The American Naturalist 180, no. 3 (2012): E54–E63.
  46. Mayr, “Recapitulation Reinterpreted.”
  47. Richardson and Keuck, “Haeckel’s ABC of Evolution and Development.”
  48. Ibid.
  49. Ibid.
  50. “MS-LS4-3 Biological Evolution: Unity and Diversity,” Next Generation Science Standards,
  51. Richardson and Keuck, “Haeckel’s ABC of Evolution and Development.”


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