The present approach, then, is based on two assumptions-first, that all humans have an evolutionary history which, while antedating each individual's own existence, nevertheless exerts some form of causal influence upon the individual. Second, that from the moment of conception until death the genes and environment interact to have an impact (minute or colossal) on virtually everything the individual does, feels, thinks, and believes. That is the way it is and will be for all living things.
Tracking the evolutionary origins and cultural development of such a complex, often elusive subjective phenomenon as spirituality has to largely rely upon intuition, common knowledge, and a thin smattering of scientific knowledge. Tracking religion, however, is different. Scientific knowledge of religion- because it is so well-expressed in terms of easily observed behavioral practices and written documents- has been accumulating for over a century.
We now know for certain that at conception each human (with the exception of identical twins) has a unique combination of genes. Part of this combination is shared with other species, and a much larger part is shared with all other humans. Recent studies of adults reveal that religiosity, as a stable individual trait, has a small but not insignificant genetic component to it. This finding is of twofold interest-it accounts in part for the universal presence of spirituality in individuals living in different cultures, as well as for the fact that individuals raised in the same culture differ in the strength of their biological propensity for spirituality. Even when life circumstances are similar, some individuals will respond to spiritual teaching with great enthusiasm, others will ignore it, and still others will reject it with a passion.
THE BRAIN AND CONSCIOUSNESS
The human brain is a biological structure whose origins are in species-specific genes that have millions of years of evolutionary history behind them. The brain's development in each species' member, however, as already intimated, is influenced by each member's everyday interactions with the world. The fact that the brain is the physical locus of consciousness means it is also the locus of spirituality; no brain, no spirituality-at least as we commonly use the term spirituality. That the spiritual may take on another form, as expressed by the soul, for example, is viewed by most scientists as falling outside the realm of scientific inquiry.
The fact that spirituality's locus is the brain implies for some that it can be explained by brain neurochemistry rather than by nonphysical causes. But such an implication is not convincing. While it is true the brain operates according to physical laws, it does not follow that consciousness is a gas-like product of brain activity that follows similar laws and can therefore be observed and analyzed into elements. Even the best of current brain technology does not allow us to view subjective events. For example, experimental subjects seeing a particular brain locus turn orange during a brain scan while they are thinking of a tree will not see a tree on the monitor. They will see what looks like a neurological correlate of a tree. The gap between the orange locus and the actual subjective experience of a tree is unbridgeable for now, and probably will be forever.
While we may know our own thoughts with certainty, we know with less certainty the thoughts of others-unless they tell us. Being told by others is, however, not the only clue we rely on to determine whether they are having thoughts. Nonverbal behaviors and their accompanying stimulus situations also help us infer that thinking is taking place in another person-or in animals, as pet lovers like to tell us.
Nevertheless, what we do know for certain about such radically different entities as brain and mind is that they causally interact. Physical acts such as chewing and swallowing food reduce the conscious experience of hunger pangs. Being informed that a pill one takes will eliminate a physical ailment (even though the pill is an experimental placebo) can result in the disappearance of the ailment. Body affects mind, and mind affects body-the causal arrow works in both directions.
One of the most challenging questions facing scientists today is how the genes that contribute to building brain proteins, which in turn make thinking possible, came into existence. Evolutionary psychologists hypothesize that behavioral and psychological properties of organisms serving vital functions are products of eons of genetic evolution.