Summary of problems with claim:

When the sizes of finch beaks oscillates, it is because of an oscillating environment. The size changes within a species are large enough to explain the differences between the various species of Galápagos finches, species Charles Darwin initially thought belonged to several different families of bird. Not all of these changes oscillate, the evolution of Darwin's finches has been directional in some aspects.

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:

Review: "Evolution — A Theory in Crisis"

Review Date: 
June 1
Philip T. Spieth
Evolution: A Theory in Crisis

Evolutionary biology is in robust health. The current flurry of debates is an early sign of a new burst of growth. Some observers, apparently deceived by the hyperbole that has accompanied these debates, have mistaken growth pains for terminal illness. Michael Denton is one such observer. Evolution: A Theory in Crisis is an anti-evolution treatise. Its theme, exemplified by the title and stated explicitly in the preface, is that there is a crisis in evolutionary biology of fatal
Michael Denton
Bethesda, Md.: Adler & Adler, 1986. 369 pages.
About the Author(s): 
Philip T. Spieth
Associate Professor of Genetics
University of California, Berkeley

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.

"Lost" Genetic Information

True biological novelty can be found in many of the adaptive radiations that Explore Evolution describes. Despite this, the authors insist "There are many examples of isolated islands that are home to flightless birds and insects that have clearly lost some of the genetic information necessary to produce the traits possessed by their ancestors. Large-scale macro-evolutionary change requires the addition of new genetic information, not the loss of genetic information" (p. 77).