Haeckel's embryos
By Troy Britain

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>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.
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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), R=FCtimeyer
        (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 Athropogeny [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)=20

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:
http://www.biology.ualberta.ca/courses.hp/zoo.225/aortic-t.html
http://www.uoguelph.ca/zoology/devobio/210labs/arch1.html
http://www.uoguelph.ca/zoology/devobio/72hrchck/72ck10.htm
http://www.bartleby.com/107/13.html

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 Louise 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 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 credibility, but they do not invalidate
the mass of published evidence for Darwinian evolution. (Richardson et al. 1998,
p. 983-984)

References:
Agassiz, Louise (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) Physiol. Soc. Mag., no. 29, p.30 (cited in Richardson
1998)
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 http://inia.cls.org/~ae/ar_hb2548.htm
Anti-Evolution home page http://inia.cls.org/~ae/
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Oryginal: http://inia.cls.org/~ae/Haeckels_embryos.htm