It’s difficult for people like me to understand. How is it possible in this day and age that so many of my fellow Americans deny a basic fact of modern science? How is it possible that a significant proportion of American adults—even college-educated adults—think that our species was created de novo about 6,000 years ago in an Iraqi garden? A recent review of the psychology of denialism offers one challenging suggestion: Human brains evolved to remain creationist.

I may disagree with what you say, but I’ll defend to the death my ability not to hear it…

As I’m arguing in my new book, the usual explanations just don’t hold water. The Richard Dawkinses of the world tend to think of creationism—at least the radical young-earth kind—as a kind of simple deficit. As Dawkins famously opined in 1989, creationists would have to be

ignorant, stupid or insane (or wicked, but I’d rather not consider that).

For those of us who understand the history and nature of America’s radical young-earth creationists, Dawkins’ dismissal doesn’t fit the evidence. Even if we are staunchly anti-creationist, if we’re paying attention we can’t help but notice that plenty of creationists know a lot about evolutionary theory. They are clearly intelligent and in possession of their mental faculties. And they might be wicked, that doesn’t seem to be a primary factor in their creationism.

A recent review article in The Economist points in a more promising direction. Studies show that people will usually accept a financial penalty rather than listening to arguments from the other side. They often compare the experience of listening to opposing viewpoints to “having a tooth pulled.”

The evolution of creationism…

Why? Hugo Mercier and Dan Sperber argue that human reason is not the engine of pure enlightenment it is often considered. Instead, reasoning evolved as a way to encourage group cooperation. In their words,

What reason does . . . is help us justify our beliefs and actions to others . . . and evaluate the justifications and arguments that others address to us.

What does this have to do with the durability of radical young-earth creationism? In spite of the accusations of angry Oxonians like Richard Dawkins, creationists have not abandoned their ability to reason and weigh evidence. Rather, if these cognitive psychologists are correct, human reasoning ability will tend to lead to greater in-group cohesion.

The brains of radical creationists tend to favor evidence that supports the dominant views of their group. They tend to dismiss evidence and arguments that go against them. This isn’t something unique to creationists. All our brains work in similar fashion. We don’t weigh facts evenly or dispassionately. We don’t even hear them that way. Rather, our brains seem hard-wired to accept facts that help us fit in with our groups.

In short, why are so many Americans creationists? Because they evolved that way.