I have a simpler thought, but what you detailed out probably also plays into this...There may be a biological reason, and it may not be an exclusively human phenomenon.
http://www.msnbc.msn.com/id/39574733/ns/technology_and_science-science/
Animals (not just people) likely have spiritual experiences, according to a prominent neurologist who has analyzed the processes of spiritual sensation for over three decades.
Research suggests that spiritual experiences originate deep within primitive areas of the human brain — areas shared by other animals with brain structures like our own.
The trick, of course, lies in proving animals' experiences.
"Since only humans are capable of language that . . . (snip)
We have all had experiences when either a sequence of coincidental events line up for us in such a way that our progress is enhanced or is thwarted, or experiences in which something unexpected and highly unlikely occurs in a startling way, or any of another half dozen types of experiences that cause wonder and surprise and defy explanation. And in such situations it is pretty normal, I think, to say "what did I do to deserve this?" or "what a gift!" or other such expression that implies a superior influence that controls our destiny making decisions affecting us. It is this sort of thing that religions are made of... -I don't mean the scriptures or the religious teachings, but the underlying feeling, conviction, or suspicion. And then eventually someone elaborates and in the context of your explanation invents a religion and writes a new scripture.
It is also reinforced in many cases, originally and at points along the way, with psychological and neurological realities you mentioned along with other studies that I don't believe you referenced in which a type of temporal lobe seizure was induced in subjects who would experience "the Presence" as a consequence (eyes closed). They described it (and I have experienced this) as a clear and unmistakable feeling/awareness of Someone face-to-face with me. It is like the experience you would have of an actual person (spouse?) standing directly in front of you, 2 or three inches from you as you look at them and are fully aware of their presence, only "the Presence" happens with eyes closed. But it is that real.