Remaining factual errors and contradictions include:
- The Flat Earth Myth. One textbook [LeBel] claims that Europeans still believed in the “flat earth” until the 1500s (after Columbus). This myth has been refuted by historians, most notably by University of California historian Jeffrey Burton Russell in his book Inventing the Flat Earth (New York: Praeger, 1997).
- Human Gill Slits. At least one textbook continues to make the bogus claim that human embryos have “gill slits” [AP Biology, Glencoe; Raven and Johnson]. Ironically, another textbook by the same publisher has removed its remaining inaccurate references to “gill slits” in chordate embryos.
- Cambrian Explosion. One textbook [Holt Biology] wrongly states that the Cambrian Explosion took place over a period of 30-160 million years, when the standard accepted dating is 5-10 million years. (Another textbook, put out by LeBel, is more accurate, providing a date range of 10-20 million years.)
- Peppered Moths. Only one text that covers the peppered moth informs students about the problems with classical peppered moth experiments [AP Biology, Glencoe, Raven and Johnson]. Notably, Glencoe/McGraw-Hill has conceded that it is a “fact” (yes, a FACT) “that the ‘bird predation’ explanation of industrial melanism is no longer supported by strong experimental data” and it boasts that this “fact… is clearly stated” in its Raven and Johnson text. However, in Glencoe’s two other texts, the bird predation hypothesis continues to be presented completely uncritically—as it is in a number of other textbooks.
- Homology. A number of textbooks claim that all homologous structures, including vertebrate limbs, follow the same path of embryological development, which is false. One textbook even implies that homologous structures must share similar genes, another falsehood. [AP Biology, Thomson]
- Haeckel’s Embryos. While the publishers of two textbooks have removed these bogus diagrams, a third publisher [Thomson] has yet to release information about whether it will drop its use of Haeckel’s diagram in its AP textbook, and the Commisioner’s Report does not require the publisher to replace this diagram.
Given that Texas law requires textbooks to be free from factual errors, Discovery Institute recommends that these errors are corrected before the Texas SBOE adopt these books. Leaving false and contradictory information in biology textbooks does not serve the cause of good science education.