Origins of religion.
There is a lot of buzz lately about the "neo-atheists" like Richard Dawkins and Sam Harris and their renewed critique of religion. An issue that is lost in this debate (or at least not debated sufficiently), which is very interesting, is the question of how religion came into existence in the first place. Robin Marantz Henig's Darwin's God in New York Times Magazine yesterday goes into the specifics of this particular debate.
Human beings evolved to their present physiological state over countless generations of natural selection. Much of their culture and habits too evolved in a similar manner. This later is the subject of an exciting field called evolutionary psychology. For example, our aversion to snakes probably originated when many of the first humans died because of them. So the genes in man which cause fear of snakes, and thereby protect from them, had a natural selection advantage. These are the genes which survived. Most physical traits and behavior patterns of man must have evolved like this. There are two essential groups of these "adaptations".
One is those patterns which gave direct selection advantage. Most adaptations belong to this group. An important example is the innate human ability for language. Its selection advantages are obvious.
The second group consists of those traits or behavior patterns that are only indirect consequences of direct adaptations, the so-called "spandrels" or "by-product adaptations".
A naturally occurring example of a by-product of adaptation is the human belly button. There is no evidence that the belly button, per se, helped human ancestors to survive or reproduce. A belly button is not good for catching food, detecting predators, avoiding snakes, locating good habitats, or choosing mates. It does not seem to be involved directly or indirectly in the solution to an adaptive problem. Rather, the belly button is a by-product of something that is an adaptation, namely, the umbilical cord that formerly provided the food supply to the growing fetus.[Link]
The fundamental disagreement among scientists debating origins of religion is whether religion is a direct adaptation or a spandrel. The above article in NYT goes into details of this disagreement and is quite fascinating.
It seems very probable that religion (or more generally the capacity to believe without evidence) is hard-wired into human beings. Numerous experiments among children establish this. Note that this is independent of whether religion is a primary adaption or a spandrel. The fact is that humans have an innate propensity to religion. The dispute is only how this propensity evolved.
Personally I am more inclined to take the the view of "by-product theorists", those who believe that religion evolved as a side-kick of other direct adaptations. It is hard for me to believe that religion could have given direct selection advantages.