By Mark Cogan
Arizona Daily Wildcat
October 29, 1997

Column mischaracterizes evolution argument

Editor:

Most people, it seems, do not understand evolution, and Rachel Alexander is among them. Her 'Darwinian Dogma' column (10/22) is a tour de force of popular misconceptions; sadly, it seem she has nothing new of her own to add.

In her first sentence(!) Alexander characterizes evolution as "...the scientific explanation for how life originated." This is incorrect; the theoretical aspects of evolutionary theory simply address questions concerning how evolution progresses. The origin of life, and the exact nature of the earliest living forms, are not subjects which evolutionary theory concerns itself with (abiogenisis is the study of the early origins of life).

In the majority of the column, Alexander makes remarks concerning the paucity of transitional fossils; unfortunately, most of what she says is simply incorrect. Paeleobiologists have unearthed many, many transitory fossils, and most vertebrate species have well-defined lineages. It is simply not true that "Every horse... beginning with the Oligocene... had one functional toe..." There are several genera of late Oligocene and Miocene proto-horses (Mesohippus, Parahippus, and Merychippus among them) with three toes; the first single-toed grazing horse, Dinohippus, did not appear until the late Miocene (~12 million years ago, well after the Oligocene period), and was preceded by a very clear lineage of three-toed horses whose side toes were decreasing in size while adopting a more "spring footed" posture.

Similarly, Alexander's comments regarding Gould and Eldredge's theory of punctuated equilibrium are also incorrect. The pair devised the theory to explain, not why "there were no transitory fossils," but why the numerous transitory fossils that do exist were not evenly distributed. As Gould himself said: "...paleontologists have discovered several superb examples of intermediary forms and sequences, more than enough to convince any fair-minded skeptic about the reality of life's physical genealogy." (Natural History, May 1994).

There is more in Alexander's column, but none of it is anything new; these same objections, and many like it, are quite common in anti-evolution (not to mention Creationist) literature. They are also readily disabused by reading, say, a first-year biology textbook. Alexander's central thesis - that evolutionary theory is dogmatic and unquestionable - is also a gross mischaracterization. Those aspects of evolution about which there are open questions are debated among biologists; Gould and Eldredge's theory, for example, is by no means universally accepted. What is not in doubt is the verified, undeniable fact that evolution does occur. The exact mechanisms by which it occurs (by natural selection or some other means) is subject to some debate.

I won't ask why Alexander hasn't attempted to check her facts; I'd recommend that she (and anyone else who is interested) at least have a look at the talk.origins archive (www.talkorigins.org). She is correct when she says that macroevolution requires "serious proof"; it does. The reason why evolution is maintained as a tenable explanation for the diversity of life is because there is serious proof, not because of blind dogmatism.

Mark Cogan
Non degree-seeking graduate student.