Haeckel's embryos

By Troy Britain © 2001

From HB2548: Haeckel’s Embryos; (ii) Proven false in 1874 by Professor Wilhelm His, Sr. Ernst Haeckel was convicted of fraud for this in 1874. Human embryos never have gills -- not even rudimentary ones.

Claim #1: Haeckel’s Embryos; (ii) Proven false in 1874 by Professor Wilhelm His, Sr.

Wilhelm His and Ernst Haeckel were bitter enemies who frequently publicly attacked each other with claims of dishonesty or incompetence.  British embryologist Michael K. Richardson, the source of much of the recent discussion about Haeckel's supposed frauds, stated in one of his articles on the subject that His failed to make a convincing case against Haeckel:

Haeckel's past accusers included His (Leipzig University), Rütimeyer (Basel University), and Brass (leader of the Keplerbund group of Protestant scientists).  However these critics did not give persuasive evidence in support of their arguments. (Richardson et al. 1998, p. 984)

    Richardson went even further in a recent letter to the journal Nature suggesting that His may have produced inaccurate drawings of embryos as well, stating that "there is evidence of sleight of hand" on both sides of the feud between Haeckel and His (though he believes the evidence is better against Haeckel). (Richardson & Keuck 2001, p. 144)

    As for Haeckel himself, he responded to some of these accusations in the preface to the third edition of his book The Evolution of Man:

Many naturalists have especially blamed the diagrammatic figures given in the Anthropogeny [The Evolution of Man]. Certain technical embryologists have brought most severe accusations against me on this account, and have advised me to substitute a larger number of the elaborated figures, as accurate as possible.  I, however, consider that diagrams are much more instructive than such figures, especially in popular scientific works.  For each simple diagrammatic figure gives only those essential form-features which it is intended to explain, and omits all those unessential details which in finished, exact figures, generally rather disturbed and confuse than instruct and explain. The more complex are the form-features, the more do simple diagrams help to make them intelligible.  For this reason, the few diagrammatic figures, simple and rough as they were, with which Baer half a century ago accompanied his well-known-known "History of the Evolution of Animals," have been more serviceable in rendering the matter intelligible than all the numerous and very careful figures, elaborated with the aid of camera lucida, which now adorn the splendid and costly atlases of His, Goette, and others.  If it is said it that my diagrammatic figures are "Inaccurate," and a charge of "falsifying science" is brought against me, this is equally true of all the very numerous diagrams which are daily used in teaching.  All diagrammatic figures are “inaccurate.” (Haeckel 1876)


    Though Haeckel defended the relative accuracy of his figures he nevertheless modified them in later editions of his book to make them more technically accurate, a fact even noted by Haeckel's modern critic Michael Richardson. (Richardson 1998, p.1289) While it might be true that in hindsight both Haeckel and His's figures were not always entirely accurate, none of the minor errors they may contain once corrected change the status of the evidence they illustrate for evolution. 

Claim #2: Ernst Haeckel was convicted of fraud for this in 1874.

    This is a common creationist claim against Haeckel for which there seems to be no historical evidence.  Unfortunately this apparent myth has taken such a hold on discussions of Haeckel that even some mainstream scholars have been taken in by it.  For example Michael Richardson repeated this claim in one of his articles (Richardson 1997, p.30) (Anon. Ed. 1997, p.23) after reading it in a newspaper in the U.K. (Hamblin & Moore 1997, p.18) This story, and Richardson's use of it, was called into question by two German biologists in a letter to the journal Science:

To some of them [anti-Darwinists] every sort of vilifying argument [against Haeckel] was welcome.  This seems to still be true today, as is evidence from recent claims in the British press that Haeckel had been convicted by his university of alleged fraud.  On being asked to disclose their sources, one of the respective authors kindly referred us to a book agitating against the origin of man from other primates (which in turn gave no relevant reference), while the other did not answer our queries.  Because, to our knowledge, no respectable historical source mentions this conviction of Haeckel, we conclude that the claim for it must be based on hearsay, not fact. (Sander & Bender 1998, p.349)


    Michael Richardson recognized his error in repeating this undocumented story and wrote a retraction shortly thereafter:

I am concerned to find that I may have helped perpetuate a Creationist myth… The claim that Ernst Haeckel was convicted of fraud was made in The Times.  I relied on that statement in a subsequent publication without seeking a primary source -- clearly a mistake on my part. (Richardson 1998a, p.1289) 


    There appears to be no evidence that Haeckel was ever tried for fraud in the Jena university court, much less that he was convicted of it. This appears to be a persistent creationist myth, like Darwin's supposed deathbed conversion.  If the anti-evolutionists want to use this claim, it is incumbent upon them to produce references to primary material that would substantiate it.  None to our knowledge have ever done so.

Claim #3: Human embryos never have gills -- not even rudimentary ones.

    This is a half-truth.  While it is technically correct that humans don't ever have gills (since they never function as respiratory organs), humans and other terrestrial vertebrates do have at one point in their embryological development the same structures that in fish and the larva of amphibians become gills.

    For example mammals (including humans) and the other terrestrial vertebrates (reptiles, birds) develop pharyngeal (sometimes called branchial, or visceral) clefts and pouches (clefts on the outside, pouches on the inside) in the neck and throat. The only thing keeping them from being true slits is a thin membrane of skin (which in the first pair of "slits" becomes the ear-drums).  While these "slits" do not normally open in mammals, they do open, and then close up in amphibians, reptiles and birds.  The common creationist claim that the exterior clefts are merely "flexion folds" is totally false.  They are the outsides of the "slits" which have corresponding pouches in the throat.

    Aortic arches (blood vessels), which travel in between each of the cleft/pouches, also develop in humans and other terrestrial vertebrates.  However unlike fish and amphibian larva, terrestrial vertebrates do not develop the finer capillaries (that grow off the aortic arches) that are used by fish to absorb dissolved oxygen from the water in which they live.  So we develop the larger "gill" blood vessels but not the smaller ones.

    In addition to having the cleft/pouches and aortic arches, the embryos of terrestrial vertebrates also have pharyngeal arches (cartilaginous supports) and nerves which also run in between the cleft/pouches just as they do in the gills of fish. These facts can be found in just about any medical (human) embryology or comparative vertebrate anatomy textbook, and they have been known since before the scientific community accepted evolution.

    See the following for examples:





    So while it is technically true that humans never have gills (a derived structure with the specific function of respiration), they do have embryonic structures that in fish develop into gills.  The developmental fate of these embryonic structures that in terrestrial vertebrates develop into various derived features (the hyoid apparatus, tympanum of the ear, etc.) is in fact supportive of evolutionary biology.

    Some modern creationists like to claim that calling these structures "gill-slits" is somehow reading evolution into the evidence.  However the fact is that many pre-Darwin creationist scientists recognized the significant of these embryonic features and tried to understand why God chose to give the embryos of "higher vertebrates" structures like those of fish.  For example there was Louis Agassiz, a creationist and fierce opponent of Darwin's theory who said the following:

The higher Vertebrates, including man himself, breathe through gill-like organs in the early part of their life.  These gills disappear and give place to lungs only in a later phase of their existence. (Agassiz 1874)

    While Agassiz was wrong about "higher vertebrates" breathing through their "gills", he clearly recognized the existence of these gill-like structures (to the point of calling them gills) even though he wasn't an evolutionist.   This illustrates the fact that the recognition of the similarities of embryonic structures across taxa was independent of the acceptance of evolutionary biology.  Just as the concept of the geologic column came to be part of the supporting evidence for evolution (even though its originators were creationists), so too did the recognized and established facts of embryology in the early 19th century. 

    Finally, the embryological evidence in support of evolutionary biology is in no way dependent upon the diagrams of Ernst Haeckel (despite their continued use in textbooks).  Creationist attacks on Haeckel and his figures are a straw-man argument in which they falsely equate all the evidence from comparative embryology to Haeckel's supposed fraud.  Whether or not Haeckel committed deliberate fraud, the actual state of the evidence is unchanged and supportive of evolution.

To recapitulate:

    1) Wilhelm His is not necessarily a reliable source of information regarding the scientific status of Haeckel's work.  He and Haeckel were openly hostile to each other his opinion could hardly be considered unbiased.  And some have questioned the accuracy of His's drawings as well.

    2) There is no historical documentation for Haeckel having ever been tried much less convicted of fraud.  This story appears to be a myth.

    3) While it is technically correct that humans and other terrestrial vertebrates do not posses "gills" as embryos, they do posses structures that appear to be homologous in great detail to the structures of fish embryos that develop into gills. The recognition of this fact is not dependant on the acceptance of evolution. However the retention of these gill-like structures in the embryological development of terrestrial vertebrates is best explained by descent with modification from a fish-like ancestor.

    4) The evidence from embryology (such as the existence of pharyngeal pouches) is not in any way dependant on Ernst Haeckel or his drawings, fraudulent or not.  Or as Michael Richardson put it:

On a fundamental level, Haeckel was correct: All vertebrates develop a similar body plan (consisting of notochord, body segments, pharyngeal pouches, and so forth).  This shared developmental program reflects shared evolutionary history... Haeckel's inaccuracies damage his credibility, but they do not invalidate the mass of published evidence for Darwinian evolution. (Richardson et al. 1998, p. 983-984)



Agassiz, Louis (1874) Evolution and Permanence of Type, reprinted in Darwin and His Critics (1973) by David L. Hull, p. 440


Anon. Ed. (1997) Embryonic fraud lives on, New Scientist Sept. 6, p. 23


Haeckel, Ernst (1876) The Evolution of Man V. I (3rd English edition) H. L. Fowle, NY, p. xxxiv-xxxv (preface)


Hamblin, T. J. and Moore, R. E. M. (1997) The Times Aug. 18, p.18


Richardson, M. K. (1997) The Forgotten Fraud, The Physiological Society Magazine, No. 29, p.30


Richardson, M. K. (1998) Haeckel's Embryos, Continued, Science 281:1289


Richardson, M. K. et al. (1998) Haeckel, Embryos, and Evolution, Science 280:983-985


Richardson, M. K. & Keuck, G. (2001) A question of intent: when is a 'schematic' illustration a fraud?, Nature 410:144


Sander, Klaus & Bender, Roland (1998) Science 281:349

Anti-Evolution legislation page

Anti-Evolution home page