Luskin, Haeckel, Richardson, Richards

Like Napoleon on Saint Helena, good ol’ Casey Luskin is re-fighting old lost battles again (one, two)…

Former NCSE staff member Matzke co-writes that complaints about the use of Haeckel’s drawings is a “manufactured scandal.” 277 Not only are textbooks using inaccurate drawings, but they are using them to illustrate points that are highly disputed by leading embryologists. The earliest stages of vertebrate embryos are quite different and the existence of the cherry-picked conserved stage often portrayed in textbooks as evidence for common ancestry is being called into question.

To say the least, students who are taught that the earliest stages of vertebrate embryos are highly similar, without being told of significant embryological evidence that challenges that view and the very existence of the conserved developmental stage portrayed in many textbooks, are not being adequately informed about the evidence regarding evolution.

Hmm. First, Haeckel didn’t ignore the differences in embryos in the earliest period just after fertilization (differences which are visually significant but mostly fairly trivial, due to the different amounts of yolk in different vertebrate eggs) – in fact, Haeckel himself prominently diagrammed them, as I showed here back in 2006. Whoops! And such diagrams are standard in any book which gives a thorough treatment of vertebrate development, although this may not include the most absolutely introductory general biology texts.

Second, Luskin makes it out as if it’s me and NCSE against developmental biology experts like Michael Richardson (whom he quotes), and as if we ignored the textbooks that did have the classic Haeckel’s embryo drawings. But (as I find out when I go back to the 2006 article which Luskin quotes) actually, no, Richardson’s on our side, and we counted the textbooks that had the drawings – taking the numbers directly from Jonathan Wells, no less! Not good enough for Luskin.

For those who actually want to be fair-minded about it, it’s pretty clear that what happened was that in the mid-1990s, as happens every few decades, a scientist (here, Michael Richardson) discovered the real, but moderate, problems with Haeckel’s embryo drawings. This led to some some guns going off half-cocked in the media and in popular works (e.g. by Gould), and this is the stuff which Luskin cites. In the meantime, the originator of the latest wave, Richardson, learned some more about the complex history of the drawings and the even more complex history of claims and counterclaims about “scandal” by creationists – from Haeckel’s day to today – and published an updated version of his assessment. We quote the updated version, and Luskin quotes the more heated early reactions, pretending (despite knowing better) that the later assessments don’t exist. Oh well.

For a deep, and actually fair and contextual, assessment of Haeckel’s drawings, and the history of claims of scandal and debunkings of those claims, I cannot recommend enough Robert Richards’ recent biography of Haeckel, The Tragic Sense of Life.

Here’s what we wrote back in 2006 – it was part of an article assessing the junk that the ID guys had (temporarily) gotten into the Kansas Science standards: Matzke, N., and Gross, P. (2006). “Analyzing Critical Analysis: The Fallback Antievolutionist Strategy.” Chapter 2 of Not in Our Classrooms: Why Intelligent Design is Wrong for Our Schools. Scott, E., and Branch, G., eds., Beacon Press, pp. 28-56.

Haeckel’s embryo drawings

The Kansas Science Standards state,

[Common ancestry is called into doubt by] Studies that show animals follow different rather than identical early stages of embryological development.

This is a key claim from Jonathan Wells’s book Icons of Evolution. The argument is that evolution is said to be evidenced by embryological similarities as shown in Ernst Haeckel’s famous embryo drawings, but that Haeckel “faked” the drawings to make the embryos more similar than they actually are, and that this “fake evidence” for evolution is reproduced in textbooks for school use.

The facts: Haeckel did exaggerate similarities in very early embryos of different species, and his figures, or derivatives of them, have appeared in a few textbooks (3 of the 10 textbooks that Wells examined).18 But photographs of embryos show strong and unquestionable similarities. The embryos of reptiles, birds, and mammals all resemble one another other much more strongly than do the adult forms, exactly as Darwin noted in the Origin of Species. The similarities, moreover, are not just superficial. They involve most of the fundamental pathways and structures of embryogenesis. Darwin and Haeckel asked why such different adult forms should all be modifications of what amounts to the same embryological plan–if organisms were specially created, they could just as well each develop directly into the adult forms with no embryological resemblance and no cumbersome remodelings during late embryonic life. Michael Richardson, the specialist who, in an exhaustive critique of Haeckel’s work, re-examined all the drawings, observes:

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. It also fits with overwhelming recent evidence that development in different animals is controlled by common genetic mechanisms. 19

The cry of “fake” from Wells and friends is a completely manufactured scandal.

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18 Alan D. Gishlick, “Icons of Evolution?” See especially Figure 8, comparing embryo photos, and Figure 10, comparing textbooks, at: http://www.ncseweb.org/icons/figures.html

19 Michael K. Richardson, James Hanken, Lynne Selwood, Glenda M. Wright, Robert J. Richards, Claude Pieau and Albert Raynaud (1998). “Letter.” Science 280(5366): 983. http://www.sciencemag.org/cgi/content/full/280/5366/983c