This, That and the Other Thing:

Sometimes evolution by natural selection can be very straight forward. For example, smaller beaks might be more cost efficient at acquiring available resources in a particular habitat. At other times,evolution by natural selection can be the proverbial catch 22. For example, aging. Why has evolution selected for aging? Or, why would aging be selected for, why not eternal physical life? Why grow old? Pain, another good example of an evolutionary conundrum. Why would natural selection select for pain instead of against it? How does pain increase my Darwinian fitness? What about the hypothesized god-gene (VMAT2), thegene that predispose us to religion-neutral spiritual beliefs, experiences and interpretations. That is to say, why would natural selection select for our belief in a supreme being (regardless of a specific religion). How is this increasing my evolutionary fitness. What are the costs to such beliefs from an evolutionary perspective?

In an original, well researched (references are expected), organized and well written essay of appropriate academic level (3000 level University) make an argument that demonstrates your understanding of evolution by natural selection for either Aging, Pain, or the hypothesized God-gene. I am looking for a scientific argument based on available facts/data with supporting references.