Haeckel’s Embryos
November 29th, 2009
Darwin, in a letter to Asa Gray at Harvard University in September 1860, Darwin wrote that “embryology is to me by far the strongest single class of facts in favor” of the theory.
Just two months before the release of the first edition of The Origin of Species in September 1859, Darwin wrote to Charles Lyell, “Embryology in Chapter VIII is one of my strongest points I think.”
Writing in his autobiography, Darwin recalls: “Hardly any point gave me so much satisfaction when I was at work on the Origin, as the explanation of the wide difference in many classes between the embryo and the adult animal.”
Darwin’s premise was that the similarity between the structure and the embryo of animal and man was primary proof that man evolved from animals. In The Descent of Man, published in 1871, Darwin writes in the first chapter that embryology provides the “ample and conclusive evidence in favour of the principle of gradual evolution.”
Darwin was not an embryologist, and instead relied on the work of others. In The Origin of Species, Darwin gave credit to Ernst Haeckel: “Professor Haeckel in his “Generelle Morphologie” and in [other] works has recently brought his great knowledge and abilities to bear on what he calls phylogeny, or the lines of descent of all organic beings. In drawing up the several series he trusts chiefly to embryological characters [to establish evolutionary sequences].”
Based on what Darwin thought was scientific evidence concluded: “So again it is probable, from what we know of the embryos of mammals, birds, fishes, and reptiles, that these animals are the modified descendants of some ancient progenitor.”
In The Origin of Species, Darwin wrote, “Thus, as it seems to me, the leading facts in embryology, which are second to none in importance, are explained on the principles of variation in the many descendants from some … ancient progenitor”
During the twentieth-century, Haeckel’s embryos were prominently displayed in nearly every biology textbook, even though Haeckel eventually confessed that the drawings were fraudulent.
In January 1909, Haeckel’s confession was published as a letter in the Munchener Allegemeine Zeitung, an international weekly publication for the sciences, arts, and technology. In the letter, Haeckel clearly states that the drawings were contrived by “comparative synthesis” and not by accurate reproduction. Without the fraud, the expected evolutionary embryonic sequences had obvious gaps. Haeckel concedes, “a small portion of my embryo pictures (possibly 6 or 8 in a hundred) are really ‘falsified’.”
Even more sadly, Haeckel’s only defense was that fraudulent practices were an accepted practice even by some of the “most esteemed biologists” of the day. Haeckel wrote, “After this compromising confession of ‘forgery’ I should be obliged to consider myself condemned and annihilated if I had not the consolation of seeing side by side with me in the prisoner’s dock hundreds of fellow culprits, among them many of the most trusted observers and most esteemed biologists. The great majority of all the diagrams in the best biological textbooks, treatises, and journals would incur in the same degree the charge of ‘forgery,’ for all of them are inexact, and are more or less doctored, schematised, and constructed.” Indeed the scientific method had been abandoned not only by Darwin and Haeckel, but also by a large segment of the profession of biology.
Paul R. Ehrlich of Stanford University and author of the famous overpopulation book, The Population Bomb, wrote in 1963 that Haeckel’s law now only has a leading role in mythology—not in science. “This generalization was originally called the biogenetic law by Haeckel and is often stated as ‘ontogeny recapitulates phylogeny.’ This crude interpretation of embryological sequences will not stand close examination, however. Its shortcomings have been almost universally pointed out by modern authors, but the idea still has a prominent place in biological mythology.”
Like Haeckel’s embryo drawings, the history of evolution has been laced with an insidious legacy of fraud.
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Um, no. A huge amount of the Haeckel’s embryo story is polluted by creationist propaganda, hysterical press reaction, and people not bothering to look up the details. It really is true that e.g. early dog, chimp, and human embryos are dramatically similar — much more similar than their adult forms (we could live in a world where the early embryos all resembled each other as much as the adults resemble each other, or had random resemblance, but we don’t. Huh. Interesting.) The classic textbook embryos drawing’s only real flaw is not in the tetrapod embryo series at all, but in the fact that the “lower vertebrates” earliest embryo row looks too much like the tetrapod embryo (whoa! so the real data means that tetrapod embryos are more similar to other close relatives — other tetrapods — than they are to more distance relatives — fishes! imagine that!).
Any vaguely responsible telling of this story has to read Robert Richards’ works on it. It’s very complex as there were several different sets of drawings involved in different disputes ranging over 30 years — only one of them had anything to do with the textbook drawings, which in any case were revised in later editions by Haeckel himself (unfortunately, the textbooks copied from an early English translation, which copied from the first edition), and furthermore in any case actual modern photos of embryos tell the same basic story.
None of this amounts to a “fraud” in any way. The only real substantial long-lasting fraud in the history of evolution is Piltdown man — which of course never fit well and which was debunked by evolutionary scientists (read the talkorigins pages for that). Things like Nebraska man, a fake feathered dino fossil in China, etc., were all short lived until scientists discovered and debunked them, and they only persist in creationist folklore.
Eminent evolutionist Stephen Gould (not a creationist) concluded in the March 2000 issue of Natural History that Haeckel’s drawings, now famous, were characterized by “inaccuracies and outright falsification” and that “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.”
Even if Haeckel’s embryos are a complete fraud (and I am not actually conceding that, but let’s just suppose) it is not of any importance to evolutionary theory, since the evidence from embryology is absolutely not essential to the validity of the theory. Darwin may have felt that it confirmed his theories: nowadays we have ample evidence from the fossil record, genetics, etc. etc. Science has moved on since Darwin. Do you throw out Newtonian theory because Newton believed in alchemy?
You’re using typical boring creationist tactics.
Greetings – Connie!
The importance of embryology is dependent on the theory of evolution – there are numerous theories under investigation. Of course, for Darwin, evidence from embryology was “second to none.”
On the fossil record and genetics issue, the evidence is not aligned with the “slight successive” changes envisioned by Darwin. With over 1,000 references from Darwin and scientists over the past 150 years, my book, Darwin Then and Now addresses these issues along with the evidence from molecular biology.
Embryology as evidence for evolution is a relatively new area of current research. To launch this new approach, two new journals were founded: Evolution & Development, and Molecular and Developmental Evolution, an independent section of the Journal of Experimental Zoology. Even Archiv fur Entwicklungsmechanik der Organismen, founded in 1890 and the oldest journal in the field of experimental embryology, was renamed Genes, Development, and Evolution.
To support evo-devo, the National Science Foundation has established a specifi c panel devoted to the evolutionary developmental biology. The Society for Integrative and Comparative Biology (formerly the American Society of Zoologists) now has specific sections for evolutionary developmental biology.
Evolutionary biologist Brian K. Hall wrote in Scientific America in 2005 “it could be argued that evo-devo was born when Darwin concluded that the study of embryos would provide the best evidence for evolution.”
The study of embryology for evidence of evolution is now an integral part research for developing a comprehensive theory of evolution. A convergence of evidence is needed to develop a cohesive theory of evolution. Issues faced at the Altenberg Summit during the summer of 2008, highlights why evolution continues to be a theory in crisis.
I am struck by the dishonesty of Rihard Nelson in this attempt to link Darwin’s seminal work with Haeckel’s embryo drawings. Several facts need to be brought out here. First, when Darwin published the first edition of Origin of Species in 1859, Haeckel was a 25-year old student. There is no mention of Haeckel until the 6th edition published in 1872, when Darwin made the quoted reference to Haeckel’s 1866 book “Generelle Morphologie”.
Second, this book, to which Nelson kindly provides a link, includes 30 drawings of invertebrate forms, but no vertebrates. The drawings of vertebrate embryos in question were first published in his 1868 book, Natürliche Schöpfungsgeschichte, 9 years after Darwin’s first edition of Origin of Species. Of this work, Darwin noted in the introduction to his 1871 book, The Descent of Man, that that if Natürliche Schöpfungsgeschichte “had appeared before my essay had been written, I should probably never have completed it”, indicating that Darwin was not influenced by Haeckel’s vertebrate drawings at least up to the point at which he had completed his third book.
In fact, it was Haeckel who was highly influenced by Darwin, not the other way around. All of this information is freely available and easy to find. If nothing else, the well-established chronology should have made Nelson think twice before trying to rewrite history.
Greetings – David Levin!
Appreciate your interest in writing the post and would like to reply to your comments.
You wrote: “First, when Darwin published the first edition of Origin of Species in 1859, Haeckel was a 25-year old student. There is no mention of Haeckel until the 6th edition published in 1872, when Darwin made the quoted reference to Haeckel’s 1866 book “Generelle Morphologie”.
My Reply: First, since there was no mention of Haeckel’s age in the post, the criticism is irrelevant. Second, while Darwin did not refer to Haeckel in the 1st edition, Darwin actually refers to Haeckel starting with the 5th edition published in 1869 – not the 6th edition – see page 515 in the 5th edition. Since there was no mention of which edition contained a direct reference to Haeckel in the post, the criticism is irrelevant.
You wrote: “Second, this book, to which Nelson kindly provides a link, includes 30 drawings of invertebrate forms, but no vertebrates.”
My Reply: Since Haeckel’s famous drawing on the post (not a link) are labeled, reading from left to right: “Fish – Salamander – Tortoise – Chick – Hog – Calf – Rabbit – Human”, a series with vertebrates, the criticism is unfounded.
You Wrote: “The drawings of vertebrate embryos in question were first published in his 1868 book, Natürliche Schöpfungsgeschichte, 9 years after Darwin’s first edition of Origin of Species. Of this work, Darwin noted in the introduction to his 1871 book, The Descent of Man, that that if Natürliche Schöpfungsgeschichte “had appeared before my essay had been written, I should probably never have completed it”, indicating that Darwin was not influenced by Haeckel’s vertebrate drawings at least up to the point at which he had completed his third book.”
My Reply: Since Darwin referred to Haeckel in the 5th edition in 1869 (1869 is before 1871), your point is wrong.
You Wrote: “In fact, it was Haeckel who was highly influenced by Darwin, not the other way around. All of this information is freely available and easy to find. If nothing else, the well-established chronology should have made Nelson think twice before trying to rewrite history.”
My Reply: Agree that Haeckel was influenced by Darwin—and vice versa, too. Please re-check you dates and inferences.
Allow me to simplify my criticism. Origin of Species, which was published in 1859 after Darwin had sat on his ideas for 20 years. At this time, Heackel was just a 25-year old student who had not yet done or published any work. Therefore, Darwin’s thinking in Origin of species was clearly not influenced by Haeckel’s controversial 1868 drawings, as your original post implied.
Greetings – David Levin!
You Wrote: “Origin of Species, which was published in 1859 after Darwin had sat on his ideas for 20 years.”
My reply: Agree
You wrote: “At this time, Heackel was just a 25-year old student who had not yet done or published any work.”
My reply: While this would obviously only apply in reference to the 1st edition of The Origin of Species, it should be noted that at the age of 26, Einstein’s revolutionary papers were published in Annalen der Physik. Therefore, the relevance of your comment is somewhat questionable.
You wrote: “Therefore, Darwin’s thinking in Origin of species was clearly not influenced by Haeckel’s controversial 1868 drawings, as your original post implied.”
My reply: Haeckel’s infamous drawing in 1868 did precede the publication of the 5th and 6th edition in 1869 and 1872, respectively. Since Darwin specifically refers to Haeckel in the 5th and 6th edition, the effect of 1868 Haeckel drawing on Darwin cannot be excluded. In the 5th edition Darwin wrote, “Professor Häckel in his ‘Generelle Morphologic’ and in several other works, has recently brought his great knowledge and abilities to bear on what he calls phylogeny, or the lines of descent of all organic beings. In drawing up the several series he trusts chiefly to embryological characters… He has thus boldly made a great beginning, and shows us how classification will in the future be treated.” Please note—the original post does not state that Haeckel’s drawing had any influence on Darwin. You are correct to state that your inference was “implied.”
For Darwin, however, the perceived evidence from embryology was central to the theory. In the 1st edition of The Origin of Species Darwin wrote “Thus, as it seems to me, the leading facts in embryology, which are second to none in importance”. (page 535)
Actually, the point of the original post was not with Darwin’s use of Haeckel’s 1868 drawing, but that the 1868 drawing had been widely used as evidence for evolution in biology textbooks throughout the 20th century even though Haeckel had even stated that the drawing had been a fabrication.