Homo sapiens evolved to be socially intelligent. Over millions of years, perhaps more, the primate brain evolved special machinery to allow us to think socially, to build abstract concepts of each other's minds and to react emotionally to each other in a way that more or less maintains the social web. In one theory that is gaining greater acceptance, the social machinery in the human brain is the direct cause of spirituality. Spirituality is the human brain doing exactly what it is exquisitely well evolved to do. It is the functioning of our social intelligence.
If spiders could ever become super intelligent, they might see the world through the metaphor of a web. They might talk about sticky strands of thought. They might envision a universe pulled out of a spinneret. They might judge beauty by radial symmetry. Looking at the moon, they might see a web-in-the-moon instead of a man-in-the-moon. The natural talent of humans is to spin metaphors of minds and intentions, and that is how we evaluate almost everything around us. We understand and react to the world through our social capability. It defines us more than any other trait. Even language is a refinement of social communication. We are truly Homo socialis.
Yet the theory that spirituality is a product of social intelligence seems to have certain limitations. If spirituality is defined rather narrowly as the human tendency to believe in a spirit world -- in ghosts, gods, angels, and life after death -- then the explanation is plausible. We believe in spirits because we are predisposed to see minds in the things around us. But to most people, spirituality has a much larger halo of meaning including moral decency and love and religious awe and an all-embracing sense of fellowship. How are these spiritual experiences products of an evolved social machinery?
It may be that the more emotional, less tangible aspects of spirituality are particularly well explained by the theory of social intelligence.
Awe, for example, is at its root a social emotion. Its utility lies in shaping our behavior toward others, especially others that we perceive to be wiser or more powerful than us. It is one ingredient in hierarchical social structure. Awe of a beautiful landscape, awe of music (another spiritual experience I've written about before), awe of the spread of stars as you look up at night, all of these instances of awe are traditionally connected in a hazy way in people's thoughts and feelings with awe of a larger, deistic presence. In the social-intelligence theory of spirituality, these instances of spiritual awe are the result of bits of a social machinery constantly spinning, constantly computing. Such emotional reactions follow from the human tendency to see almost everything in our world through the filter of the social machinery.
Religious awe may belong to a category of biological trait along with male nipples and the gill slits in human fetuses. It has an understandable evolutionary past. The adaptive advantages that led to it are real, but the present adaptive advantage of it, if any, is not entirely straightforward. It doesn't need an adaptive advantage to be a part of who we are.
Note that nowhere in my description do I condemn spirituality or scoff at awe. I am not calling for its end. I am no so-called New Atheist advocating the debunking of human spiritual belief. I consider my perspective more that of a strict naturalist trying to understand the behavior of a species of animal that happens to be my own species. I have no interest in fighting a cultural war against a natural phenomenon, the intrinsic behavior of us humans, that I am trying to study.
I would love to see us humans tackle our world problems rationally, but it is difficult to do that without first understanding who we are, and my interest, scientifically speaking, is to understand who we are. We are beings that do not see the world literally or dispassionately. We see the world filtered through our most developed talent, our social intelligence, and spirituality is a direct consequence.