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Limits on Evolution

Summary of problems:

Explore Evolution never defines "biological information," except through error-laden analogies to computers. Biologists have no trouble showing how new information (in the sense used by information theorists) originates, nor how new genes, kinds of cells or tissues evolve.

Horses and Dogs

Summary of problems:

The claim that there are limits on evolution – as evidenced by the limits on the speed of horses or the size of domestic dogs – is essentially a restatement of the creationist doctrine that types (or baramins) cannot evolve into one another. Explore Evolution argues that if natural selection cannot produce a certain change in a matter of decades, it could never produce that change.

Biology Texts

Summary of problems:

Darwin's finches and peppered moths are unquestionably examples of natural selection. They are far from the only examples offered in biology textbooks.

Full discussion:

Explore Evolution claims:

Artificial vs. Natural Selection

Summary of problems:

Artificial selection and natural selection are different forms of the same process. Treating the relationship as a mere analogy assumes that differences are greater than they actually are.

Full discussion:

Natural selection simply requires certain conditions. When they occur, natural selection will occur:

Doubting Common Ancestry

Explore Evolution claims that some people who doubt common ancestry accept fixity of species, so biogeography doesn't prove anything to them. One such 19th century scientist:

Biogeographic predictability

Explore Evolution asserts "the evidence [from biogeography] is completely consistent with other views of the history of life, in which small-scale changes in form and features do occur within separate but disconnected groups of organisms" (p. 79). In order for a claim to be good science, it is not enough that it be "consistent" with the evidence, it must actually make testable predictions. In the terms stated, this "orchard" model offers no testable predictions, as it is infinitely malleable.


The marsupial faunas of South America and Australia are at least as ecologically diverse as placental mammals worldwide (with some exceptions, see the discussion of developmental constraints in our response to chapter 8). The convergent evolution of Australian mammals and placentals found in comparable habitats elsewhere shows the power of evolution to adapt species to similar conditions. That they have similar adaptations to those found in placentals, but achieve such adaptations by different means, indicates how flexible evolutionary processes can be.

Fixity of Species

As John Wilkins explains, "The idea that species were universally thought to be fixed prior to Darwin is simply wrong — many creationist thinkers of the classical period through to the 19th century thought that species could change." Linnaeus, the father of modern taxonomy, began his career committed to the fixity of species, but began accepting the evidence against such fixity approximately a century before Darwin's ideas were published.

Students as Jurors

Explore Evolution claims that many scientists who criticized Haeckel's embryos still support common ancestry; but students, as good jurors, should keep an open mind. Students are learners, not jurors. Their science class is a chance to gain enough context to continue their science education in college and graduate programs, where they will get the background necessary to challenge well-established science. To suggest that students should reject such science at the beginning of their scientific careers is irresponsible.

Evolutionary Predictions of Common Ancestry

Explore Evolution argues that if common descent predicts both similarity and dissimilarity of embryos, it is impossible to challenge the theory. The similarity of embryos is best explained by common descent. The dissimilarity of embryos can be explained by environmental adaptations under natural selection, and while it can cause scientists to re-evaluate particular claims of common ancestry, no embryological evidence now available would cause scientists to reject universal common ancestry.

Explore Evolution insists


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