Friday, June 01, 2007

What Senator Brownback Thinks About Evolution

In yesterday’s New York Times, Senator Sam Brownback wrote an op/ed column entitled What I Think About Evolution. He felt the need to articulate his take on the origin of species because of his reaction to a question at the first Republican presidential debate. Chris Matthews asked candidates to raise their hands if they did not believe in evolution, and Brownback’s hand went up. Because some viewers might have looked askance at Brownback’s disavowal of scientifically established fact, he set out to clarify what he meant.

In his op/ed, the Senator from Kansas asserts without qualification that “[i]f belief in evolution means simply assenting to micro-evolution, small changes over time within a species, I am happy to say, as I have in the past, that I believe it to be true. If, on the other hand, it means assenting to an exclusively materialistic, deterministic vision of the world that holds no place for a guiding intelligence, then I reject it.”

What does Brownback mean when he says he assents to “micro-evolution”? He means that he accepts that each species changes over time. For example, though he provides no examples, I take it that Brownback would not dispute the evolution of one type of bacterium that dies when exposed to an antibiotic like penicillin into a slightly different bacterium that survives in the presence of penicillin. By the same token, Brownback would probably accept the proposition that the human species has, over time, developed the immunological capacity to defend against various bacteria. “There are aspects of evolutionary biology,” he tells us, “that reveal a great deal about the nature of the world, like the small changes that take place within a species.” (emphasis added).

What, then, does Brownback disavow? He does not say explicitly, but one can read between the lines. The repeated focus on “small changes” and “micro-evolution” implies that he rejects the theory that human beings evolved from simpler life forms (including single-celled organisms). He accordingly rejects the idea that apes and human beings have a common ancestor (even though our DNA – the foundation of so-called “micro-evolution” – indicates that we are in fact very closely related). Perhaps because it says in the Bible that God created human beings from dust, Brownback believes that human beings spontaneously came into existence by the hand of their Creator.

Senator Brownback would like readers to think that his acceptance of “part” of evolutionary theory – the part that has individual species changing slightly over time – makes his rejection of another part a small matter. The problem with this view is that interspecies evolution is the centerpiece of “the theory of evolution.” It says that species in existence today, including human beings, evolved from different species that existed millions of years ago (a great many more years, incidentally, than creationists believe would be consistent with the Biblical account). So when Sam Brownback raised his hand at the Republican debate, he joined the creationists in rejecting the best scientific evidence regarding human origins. There is nothing rational or moderate about that.