89 years ago this week, a jury in Dayton, Tennessee convicted substitute science teacher John Scopes of violating the Butler Act, which prohibited the teaching of “any theory that denies the story of the Divine
Creation of man as taught in the Bible, and to teach instead that man has descended from a lower order of animals.” Scopes was convicted of violating the act by teaching evolution and fined $100. That
conviction was later overturned on a technicality, but it would take 42 years for the Butler Act to be repealed. Of course, that didn’t settle the matter. To this day, biblical literalists have been trying, to the dismay of biologists everywhere, to deny evolution and have Creationism taught in the classroom.
This begs a number of questions. First of all, why do these religious zealots have it in for biology? Just because some people believe that the world rests upon the back of a cosmic turtle, doesn’t mean that anyone is calling for legislation banning the teaching of planetary motion in physics classes. The Bible talks about Jesus changing water into wine, but nobody demands that chemistry textbooks be changed in accordance with that. It also teaches that Moses parted the Red Sea, but the publishers of oceanography books don’t seem to be under much pressure to cover it. Why does Darwin’s theory of evolution by means of natural selection merit such special attention? What put such a biblical bee in their bonnets? I don’t have an answer for that one.
The second, and more important question is, why not teach creationism alongside evolution? That one’s easy to answer. It would utterly destroy science. That sounds hyperbolic, but it’s not. Science depends upon evaluating evidence. If we allow science students to simply ignore the evidence they don’t like or that contradicts their beliefs, it undermines the entire scientific method.
It also contradicts the entire language of science. Many Creationists will argue that evolution is only a theory, without any clue of how scientists actually use the word theory. Contrary to its use in common speech, a theory is not simply a guess. Even what scientists call a hypothesis isn’t just a guess. A hypothesis is a specific testable prediction. For instance, Darwin made a hypothesis when he said that if populations of animals and plants change over time, we should be able to see those changes in the fossil record. If we couldn’t see those changes, the hypothesis would have been disproven and Darwin would have had to go back to the drawing board and come up with a new hypothesis. He didn’t.
The word theory, as scientists use it, refers to a well-researched explanation for something that is supported by large quantities of data, and can stand up to rigorous attempts to question or undermine it. Evolution has passed that test. It has, not simply a few pieces of evidence supporting it, but literally mountains of evidence. For over a hundred and fifty years it has withstood every challenge.
There have been minor changes, for instance, Darwin thought that evolution occurred over a long period at a constant rate. Today we know that it can occur suddenly over a relatively short period, what scientists call punctuated equilibrium, but in spite of that, the central tenet of Darwin’s theory remains intact. When the environment changes, organisms with advantages that help them survive are more likely to survive and pass those advantages on to their young. Those without the beneficial advantages go extinct. You can imagine that this is a natural phenomenon or that God designed this mechanism, but whether or not it happens is not up for debate.