Slow To Learn, Slow To Correct

As many of you probably know, one of the most popular lines of evidence cited in support of evolution, Haeckel's embryos, has been known for a long time to be false. I remember when Jonathan Wells discussed this subject in a debate with Massimo Pigliucci several years ago, and Pigliucci told the audience that this sort of mistake happens in science a lot, and that it had already been corrected. But the error continued to be promoted in science textbooks. Why would it take evolutionists so long to correct the error, if they're as accurate and as concerned about evidence as they profess to be? William Dembski reports at his blog today that some textbooks have continued using Haeckel's embryos at least as recently as 2004.