How to Make Eighteen Equal Twelve - Evolution News & Views

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How to Make Eighteen Equal Twelve

Occidental College professor Donald Prothero, who along with Michael Shermer debated Stephen Meyer and Richard Sternberg on November 30, complains that folks at the Discovery Institute are now attacking him with "everything they have." Prothero writes on the NCSE's blog Panda's Thumb, "Normally, it is not worth dignifying their garbage with a response," but in this case he wants people "to get the straight facts."

According to Prothero:

When evo-devo came up in Monday's debate, Meyer and Sternberg began arguing with each other about reconstructions of a 12-winged dragonfly that I had published in my book. They tried to get a laugh by claiming that such a bug has never been found. As usual, they completely missed the point of that illustration, and failed to read any of the explanation or discussion in the caption or text. The text clearly points out that the 12-winged dragonfly is a thought experiment, an illustration to show that a simple change in Hox genes allows the arthropods, with their modular body plan of adjustable numbers of segments and interchangeable appendages on each, to make huge evolutionary changes by simple modifications of regulatory genes. This is the aspect of evo/devo that should answer structuralist Sternberg's objections to Neo-Darwinism, if he only bothered to comprehend it, and solves much of the question over how macroevolutionary changes take place.

Unfortunately, it's Prothero who needs "to get the straight facts." First, the dragonfly in his book did not have 12 wings, but 18. Second, there is no evidence that "such a bug" ever existed, so it was not "reconstructed," but invented.

Third, it is not true that Prothero's book "clearly points out that the 12-winged dragonfly is a thought experiment." According to p. 194 of the text, "Experiments have shown that a few Hox genes cause arthropods to add or subtract segments, and other Hox genes can produce whatever appendage is needed (fig. 8.18)." On page 195, the caption for figure 8.18 reads: "The evolutionary mechanism by which Hox genes allow arthropods to make drastic changes in their number and arrangements of segments and appendages, producing macroevolutionary changes with a few simple mutations (see fig. 4.5)." On page 101, figure 4.5 shows a fruit fly with legs growing out of its head (antennapedia) and a fruit fly with an extra pair of wings (ultrabithorax), accompanied by a caption stating that these show "that big developmental changes can result from small genetic mutations."

Not a word anywhere about the many-winged dragonfly being a "thought experiment."

Fourth, Hox gene mutations can not "produce whatever appendage is needed," and they do not solve "much of the question over how macroevolutionary changes take place." Prothero writes on Panda's Thumb that "a simple Hox mutation can rapidly transform an arthropod with one set of appendages into one with a different set, and make a macroevolutionary change with minimal point mutations required." Although it is true that mutations in Hox genes can have dramatic effects, those effects are never beneficial. For example, antennapedia and ultrabithorax mutants are severely handicapped, and they cannot survive outside the laboratory. Hox mutants would be eliminated by natural selection, so they are evolutionary dead ends.

Prothero doesn't acknowledge this obvious difficulty with his argument. Instead, he ridicules Sternberg for allegedly not comprehending it.

Which brings up a fifth point on which Prothero is fact-challenged. In his book, he wrote on page 45:

In August 2005, an ID creationist article on the 'Cambrian Explosion' appeared in the obscure Journal of the Biological Society of Washington. According to reports, the peer reviews were scathing and recommended rejection of the article, but the editor had creationist sympathies and let it be published anyway. Once the rest of the editorial board and the Smithsonian scientists became aware of what had been slipped past them, they repudiated the article, and the editor resigned. To my knowledge, this is the only openly creationist paper that has ever appeared in a legitimate scientific peer-reviewed journal--and only because the editor was sympathetic to their cause and violated journal policy by overruling his reviewers.

This passage is full of factual errors, the least of which are that Prothero got the year and the journal wrong. (It was 2004, not 2005, and the journal was Proceedings of the Biological Society of Washington.) More seriously, the reviews were not scathing (indeed, as the president of the Council of the Biological Society of Washington confirmed, all three recommended that the article be published); Sternberg did not violate journal policy; and he did not resign (since his term as editor had already expired when the article appeared). If Prothero had any respect for the facts, he would have read the reports of two U.S. Government investigations into the incident, both of which were publicly available before he published his libelous book.

So much for Prothero providing us with "the straight facts."

In the meantime, there may be a way for Prothero to eliminate his confusion between 18- and 12-winged dragonflies. I offer it here as a "thought experiment."