Jerry A. Coyne in The Nation:
Imagine for a moment that a large proportion of Americans–let's say half–rejected the “germ theory” of infectious disease. Maladies like swine flu, malaria and AIDS aren't caused by micro-organisms, they claim, but by the displeasure of gods, whom they propitiate by praying, consulting shamans and sacrificing goats. Now, you'd surely find this a national disgrace, for those people would be utterly, unequivocally wrong. Although it's called germ theory, the idea that infections are spread by small creatures is also a fact, supported by mountains of evidence. You don't get malaria unless you carry a specific protozoan parasite. We know how it causes the disease, and we see that when you kill it with drugs, the disease goes away. How, we'd ask, could people ignore all this evidence in favor of baseless superstition?
But that's fiction, right? Well, not entirely, for it applies precisely to another “theory” that is also a fact: the theory of evolution. Over the past quarter-century, poll after poll has revealed that nearly half of all Americans flatly reject evolution, many clinging to the ancient superstition that the earth was created only 6,000 years ago, complete with all existing species.