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By Jonathan Kane

Anyone who’s spent time debating with creationists, or has looked at my "Prattmaster" comics, will probably be aware of what a PRATT is.  The term is an acronym for "Point Refuted A Thousand Times", and it is exactly what it sounds like—an argument that for some reason is continuing to be used, despite having been refuted dozens or hundreds of times in the past.  And most us are also probably familiar with some of the more famous anti-evolution PRATTs that exist, such as “Nobody has ever observed the formation of a new species” or “If humans are descended from apes, why are there still apes?”  But these kinds of arguments, which continue being used despite having been known to be faulty for decades, are the exclusive realm of creationists, right?  Unfortunately, as I discovered last month, the answer is no.

I’ve been aware for a while that some arguments that evolution supporters use against creationism aren’t particularly good, and pointed out some of the ones which especially bothered me in this thread at Christian forums.  One of the worse examples of this is the claim that the theory of evolution has never been used as a justification for racism—the theory of evolution does not inherently support racism, but it has certainly been misused for that purpose in the past, especially during the first half of the 20th century.  Still, that argument doesn’t quite reach the level of the PRATT, mostly because it isn’t widespread enough.  But last month, I came across a much worse example that definitely qualifies.

The example is Ernst Haeckel’s embryo drawings (or more specifically, George Romanes’ copies of them).  For those who don’t know (and don’t feel like reading the linked article), these drawings purport to be a comparison betweem the embryos of eight different animals at three separate stages of development, showing how incredibly similar they are to one another in their early stages.  However, as the linked article points out, Haeckel grossly exaggerated the similarities between these embryos, to the point of repeating the exact same woodcut multiple times while labeling it as a different animal each time.  According to the 1915 book Socialism, feminism and suffragism, during Haeckel’s lifetime his conclusions about embryology were rejected as fraudulent in a statement signed by 82 professors and other scientists at 44 universities and laboratories in Germany, Switzerland, and Austria.

Of course, for an argument to qualify as a PRATT requires more than just that it’s been known to be false for a long time; it also has to be an argument that’s still commonly used.  That is where this particular argument for evolution truly stands out, because this image is continuing to appear, without any explanation of its inaccuracy, in biology books published within the past 15 years.  And these are mainstream, commonly used biology books, written by respected biologists such as Ernst Mayr and Douglas Futuyma.  I’ve scanned a few of examples of how this image is being used in their books (click on each link for the image):

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(From Douglas Futuyma’s 1998 book Evolutionary Biology: Third edition, on page 653)

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(From Ernst Mayr’s 2001 book What Evolution Is, on page 28)

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(From Donald Prothero’s 2007 book Evolution: What the Fossils Say and Why it Matters, on page 110)

I doubt that these are the only modern biology books which still use these images, but these are the three that Emily and I happen to own.

There are two things that make this fact particularly embarrassing.  The first is that well-known evolution advocates such as P.Z. Myers are continuing to claim that biology textbooks almost never use these images anymore, at least not without pointing out their inaccuracies.  I’m not sure what Myers’ conclusion about this is based on, but even Kenneth Miller rejects it as false.  Quoting from Miller’s article: “As it turns out, Haeckel's contemporaries had spotted the fraud during his lifetime, and got him to admit it. However, his drawings nonetheless became the source material for diagrams of comparative embryology in nearly every biology textbook, including ours!”  (Emphasis added.)

And the other thing which makes this embarrassing is that creationists have been pointing out the inaccuracy of this image at least since the 1970s.  The following is an image from a 1970 creationist tract by Jack Chick; while this image is from the 2002 version of the tract, I’m fairly certain it was the same in the original version, apart from the number of years that’s mentioned.

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“Wrong for 125 years and it’s still in our book.”  Chick may have misspelled Ernst Haeckel’s first name, but he still has a point.  You know something’s amiss when a mistake being made by Ernst Mayr and Douglas Futuyma is able to be pointed out by the likes of Jack Chick.

I’m hoping that the other members here will agree it’s a problem that this image is still being used by modern biology books, as well as that well-known evolution advocates such as P. Z. Myers are claiming that it isn’t.  If you disagree with this conclusion, feel free to dispute it.  But assuming that you agree with it, here is this month’s question: For ordinary people like us, what is the best way to make more scientists aware that modern biology books are still using this image, and prevent this from continuing?

Unlike this group’s other monthly topics thus far, it’s my hope that this one will be more than just a discussion.  Whatever ways we can come up with to do something about this problem, people who care about this are encouraged to actually use them to try and improve it.  I’ve already made one attempt at this myself, which is sending e-mail about this problem to Donald Prothero, the author of the book from which I’ve scanned the third image shown here.  I’m pretty sure that Douglas Futuyma has been notified about this problem already, and that he’s correcting it in the newest edition of his book.  As for Ernst Mayr, though, it’s too late in his case—he died in 2005.

There’s one other course of action that I recommend, and it’s getting other people to understand this problem who currently aren’t aware of it.  I’m thinking of P. Z. Myers in particular.  He’s well-enough known that he could make a significant difference in getting the authors of biology books to stop using this image, if he were to make an effort at this.  But as long as he continues to dismiss creationists’ objections about the continued us of this image as completely unfounded, authors of biology books are likely to remain unaware of this problem, and nothing is likely to improve. If there’s anyone in this group who regularly comments in Pharyngula, I encourage them to bring this issue up with him.

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