Darwin's God

God has always been a puzzle for Scott Atran. When he was 10 years old, he scrawled a plaintive message on the wall of his bedroom in Baltimore. ''God exists,'' he wrote in black and orange paint, ''or if he doesn't, we're in trouble.'' Atran has been struggling with questions about religion ever since -- why he himself no longer believes in God and why so many other people, everywhere in the world, apparently do. ...

Atran saw such questions as a puzzle when applied to religion. So many aspects of religious belief involve misattribution and misunderstanding of the real world. Wouldn't this be a liability in the survival-of-the-fittest competition? To Atran, religious belief requires taking ''what is materially false to be true'' and ''what is materially true to be false.'' One example of this is the belief that even after someone dies and the body demonstrably disintegrates, that person will still exist, will still be able to laugh and cry, to feel pain and joy. This confusion ''does not appear to be a reasonable evolutionary strategy,'' Atran wrote in ''In Gods We Trust: The Evolutionary Landscape of Religion'' in 2002. ''Imagine another animal that took injury for health or big for small or fast for slow or dead for alive. It's unlikely that such a species could survive.'' He began to look for a sideways explanation: if religious belief was not adaptive, perhaps it was associated with something else that was. ...

Some cognitive scientists think of brain functioning in terms of modules, a series of interconnected machines, each one responsible for a particular mental trick. They do not tend to talk about a God module per se; they usually consider belief in God a consequence of other mental modules.

Religion, in this view, is ''a family of cognitive phenomena that involves the extraordinary use of everyday cognitive processes,'' Atran wrote in ''In Gods We Trust.'' ''Religions do not exist apart from the individual minds that constitute them and the environments that constrain them, any more than biological species and varieties exist independently of the individual organisms that compose them and the environments that conform them.''

At around the time ''In Gods We Trust'' appeared five years ago, a handful of other scientists -- Pascal Boyer, now at Washington University; Justin Barrett, now at Oxford; Paul Bloom at Yale -- were addressing these same questions. In synchrony they were moving toward the byproduct theory.

Darwinians who study physical evolution distinguish between traits that are themselves adaptive, like having blood cells that can transport oxygen, and traits that are byproducts of adaptations, like the redness of blood. There is no survival advantage to blood's being red instead of turquoise; it is just a byproduct of the trait that is adaptive, having blood that contains hemoglobin.

Something similar explains aspects of brain evolution, too, say the byproduct theorists. ...

•	Darwin's God The New York Times Magazine, Sunday, March 4, 2007 Byline: Robin Marantz Henig