Dialogues

Should Evolution Be Taught in Schools?

Evasion is usually the better part of Creo valor, but Phillip Johnson deserves thanks for his cautious emergence from the closet. It turns out that he thinks that Genesis is literally false, for the world is probably very old and there have been waves of organismic creation. This may cause a bit of a stir among his friends and supporters.

Having made it to the early 19th century, I want to urge him to go further. As Darwin saw, there’s a real puzzle about why the Creator assigns new organisms the structures found in extinct ones. Why do dogs, moles, bats, whales, and humans all have the same arrangements of bones in the forelimb? Not because it’s a particularly bright design idea–it isn’t–but because they all came from a common ancestor with that arrangement. Similarly the whale’s rudimentary pelvis and our tiny tailbones are the vestiges of structures that are now nonfunctional but which our ancestors put to work. As 20th-century biologists started to look at the internal details of the cell, the banding patterns on chromosomes and, most recently, the details of DNA sequences, they found more and more of the same. The bands on human and chimp chromosomes are stunningly similar–you can line them right up and see just where the fusion on pair number two occurs. But the most powerful evidence comes from looking at DNA. The genomes of contemporary species are full of junk, bits and pieces that have been carried over from ancestral organisms. Most of them are simply useless, but sometimes these residues of past functional DNA are actually damaging to their possessors. Some human diseases result from over long repeats that come from the buildup of junk DNA.

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Sadly, most academics find themselves reading the occasional student essay that sounds familiar. Confronting the author with the source, they would not be reassured if the student declared that the words had come in some miraculous vision. Similar words and phrases testify to inheritance. So too with the history of life.

Minute examination of the relations among organisms at all levels screams out the Fact of evolution. The alternative is to suppose not “intelligent design” but, at best, “whimsical design” and, at worst, “sadistic design” (remember the residues that are actively harmful). So Phillip Johnson’s creator is a klutz from the bottom of the engineering class who carefully hands on to newly created organisms the remnants of structures in the organisms who have just gone extinct?

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Why would anyone believe so absurd a fantasy? Because some people are desperate for any creator, at any price. (“Religion must be preserved. We must get it back into the classroom.”) Johnson’s official reason is the alleged powerlessness of natural selection. This tells us more about his lack of understanding than about the process of selection. Johnson and his anonymous friend seem to think that there’s no material for selection to work on. Now, it’s true that most mutations are bad for their bearers, in the particular environments in which those bearers find themselves. But not all. Especially when the environment changes, there can be mutations that assist an organism and enable it to reproduce more successfully. We see this in the wild with the emergence of resistance to DDT, the return of strains of tuberculosis that cannot be treated by the usual antibiotics, and, most tragically, in the exceptional mutability of the AIDS virus. Twentieth century geneticists have induced mutations in bacteria and fruit flies that enable those bacteria to survive and reproduce in special environments, in conditions where the unaltered forms would have died out. Johnson’s charge about the impotence of natural selection is just ignorant bluster.

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Of course, it would be wonderful if experimental genetics could produce a new species of bird, say, in the lab. The most striking demonstrations of creative natural selection are with microorganisms and insects–creatures with short generation times and well-understood genomes. As we learn more, we may be able to see natural selection do its dramatic work with more complex organisms. But there’s no reason to doubt that what we observe on the microorganism level doesn’t scale up.

Johnson seems less interested in the science than in his myth of an anti-religious intellectual elite, bent on suppressing heresies. But the reasons for wanting to teach evolution are perfectly straightforward. Scientists and educators don’t want children to be fobbed off with pseudo-solutions to hard problems–“whimsical design” as the universal panacea. Under my goading, Professor Johnson seems to have staggered into the early 19th century (after all, he does seem to have given up on Genesis). The students of Kansas deserve to be prepared for the 21st.

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