Why, according to one poll, do 70 percent of Americans believe in angels? Or that Saddam Hussein orchestrated 9/11? How did hundreds of people come to believe that they have been molested and impregnated by aliens? After all, there is absolutely no solid evidence to support any of these claims and considerable evidence to the contrary. The answer, according to evolutionary biologist Lewis Wolpert, is that we are wired to believe. In evolutionary terms, it's in our best interest to wish upon a star.

In "Six Impossible Things Before Breakfast," we are treated to a lively, if sometimes irritable, biological explanation for the way we arrive at a variety of colorful conclusions. Handier still in this election year, this newly released paperback edition functions as a pocket primer on rational thought, a sort of "Critical Thinking for Dummies."

Wolpert himself does not disguise his own bias: "I am an atheist reductionist materialist," he states with a touch of defiance. He finds the idea that 45 percent of Americans don't accept Darwinian evolution both puzzling and infuriating. Where, in the human brain, and when, he asks, did our ability to deny actual evidence develop? The answer is locked away in our genes.

His investigation of beliefs about science, morality, religion and reality is always energetic, often soaked in genteel black humor: "Ninety-four percent of academics believe they do a better job than their colleagues," he writes. "Am I different? Believe I am!"

So is everything fantasy except the fact that, as one biologist says, "there is at bottom ... nothing but pointless indifference. ... We are machines for propagating DNA"? Well, in Wolpert's book, no less a scientist than the director of the Human Genome Research Institute asks if God might have used the mechanism of evolution. What's important about this treatise, finally, is not its conclusion, but the infectious delight that Wolpert takes in the process of scientific, evidence-based reasoning.

Emily Carter of Minneapolis wrote the short-story collection "Glory Goes and Gets Some."