For a number of years I have been ruminating on the connection between our genetic make up and the human proclivity for creating gods, demons, ghosts, goblins, long legged beasties and things that go bump in the night. I am 99% convinced that a large percent of human beings are genetically predisposed to irrational belief to one degree or another. The most pronounced irrationality being religion.
The best demonstrable evidence of the genetic predisposition toward religion is that every human population, with few if any exceptions, embrace a supernatural religion or supernatural beliefs in one form or another. Many populations (gene pools) have been separated from each other by tens of thousands of years, (African populations were separated from the European and Asian populations by at least 70,000 years) .
This acceptance of the supernatural is not a cultural phenomenon as cultural traditions don't survive for millenniums – but the essential human genome does, as does our brain structure and brain chemistry. This strongly suggests that the genetic mechanism existed very early in human evolution. There is good evidence that the Neanderthal believed in an afterlife and practiced totemic rituals. As both H. sapient and H. neanderthalisis are descendant of H. erectus the traits very likely existed within that hominid line as well.
This predisposition did not arise from some errant mutation. Complex structures or behaviors do not appear, created out of whole cloth, due to a mutated gene, but rather, they arise from precursor, well established, traits; traits that were present in other animals to some degree but modified to new uses in humans. This is the same process by which complex organic structures such as the mammalian eye or bacterial flagella evolve.
It is my contention that the two principle precursor traits were the ability to connect cause and effect and the ability to recognize patterns in the environment, traits shared with many animals.
However, humans (and possibly the entire Hominid line) went beyond simple recognition and begin to actively seek out the causes for the phenomenon they witnessed and patterns in their environment (both premium survival traits). But, patterns changed with no apparent reason and events occurred with no observable cause.
This did not curtail the human desire to find cause for what they witnessed. Unfortunately, finding cause was well beyond their capacity to understand much of the natural phenomena around them. As such, they attributed volition to weather, earthquakes, fires, floods and the animals they relied on and feared – Animism.
Although primitive, even at this very early stage of religious development, the notion of a “personal god” or guardian spirit in the form of totemic animal spirits existed.
This evolved from "the spirit within the thing"-Animism, to a god figure ruling the elements ( rain gods, season gods, sun gods, fertility gods, harvest gods, volcano gods, and many others) and further to, protective gods of broad powers, but limited to a locality, (henotheism), then gods of human attributes and human form (war gods, hunter gods, pleasure gods, chief gods) and finally to the all powerful, omnipresent creator gods and monotheism.
The progression of religious sophistication is a cultural artifact that parallels other levels of cultural sophistication, however, the genetics, brain architecture and brain chemistry, specifically the proteins produced by those genes (proteomes); that apparatus was already in place.
Like many traits within a species there is generally a variability as to the expression of the gene or genes (the phenotype) and there are epigenetic factors that may trigger, suppress or enhance the genes expression . This could range from strong, phenotype , expression to weak or no expression

The continuation of the trait or traits was strongly re-enforced by society. Religion was the most enduring dictator of the local moral and behavioral standards. It had an influence on society that constrained secular rule and the whims of temporal rulers by providing a continuity of the values and structure of the society despite the temporal ruler's efforts to the contrary - the perpetual church/state tension that has existed throughout recorded history on who controls the populace and the wealth. [I use church in the broadest sense of the word]
Unfortunately this didn't just apply to bad decisions by temporal leaders but also to decisions that would have bettered the social condition for the people or eliminated human suffering and , in fact, more often than not the church in league with the state championed the worst subjugation of the people.
Institutionalized religion also had a definite influence on the increase in frequency of the relevant gene(s) within the gene pool, in that, those that did not hold to the religious dictates were likely shunned, ostracized, exiled or even killed – the effect being those unbelievers and doubters were less likely to reproduce within the population and did not pass their “genetic defect” to the next generation.

All of this, however, begs the question; how does the genetic and subsequent brain chemistry and brain anatomy lead to the irrational acceptance of a transcendent, non-corporeal entity(s) that directly interacts with and influences the real world ? Further, why do large segments of the population succumb to the irrationality with unwavering acceptance while other parts of the population (like here on A/N) completely reject such notions ​?
Some of the answers may reside in a region of the brain, in the parietal lobe, that functions to distinguish between the perception of the self (a concept as elusive as “soul” and “free will”) and that which is outside of the self. In other words it allows us to recognize that which is an external phenomenon and that which is generated internally. It is, I speculate, this architecture of the brain and the associated brain-chemistry that controls the degree of religiosity demonstrated by the human species.
Andy Newberg, a neuroscientist/physician with a background in space medicine, writes, ”When we think of religious and spiritual beliefs and practices, we see a tremendous similarity across practices and across traditions.
The frontal lobe, the area right behind our foreheads, helps us focus our attention in prayer and meditation.
The parietal lobe, located near the backs of our skulls, is the seat of our sensory information. Newberg says it's involved in that feeling of becoming part of something greater than oneself.
The limbic system, nestled deep in the center, regulates our emotions and is responsible for feelings of awe and joy”

Newberg calls religion the great equalizer and points out that similar areas of the brain are affected during prayer and meditation. Newberg suggests that these brain scans may provide proof that our brains are built to believe in God. He says there may be universal features of the human mind that actually make it easier for us to believe in a higher power.”
The effect would, in all likelihood, be a variable trait, with it's expression ranging from a strong affective behavior to a weak or no affective behavior.
One extreme of affectation would be the inability to separate strong internal perceptions with the real world. The result would be one who experiences that internal perception as reality and can no more be dissuaded of it's authenticity than one can be dissuaded that they have a nose on their face.
At the other extreme are ...well... us. If god showed up on any of our front porches, preformed several miracles including turning an empty beer can into a case of Maker's Mark Whiskey and a pound of sticky, skunky weed, we would still want to see some ID (although the whiskey and weed trick would probably peak my interest).
For us godless heathens the line of separation between internal and external phenomenon is to pronounced to allow our internal world to overflow in to the real world, unless we are suffering brain damage or a mental disorder, under the influence of a hallucinogenic drug , or willing suspend belief for our temporary entertainment. Even then, the aforementioned phenomenon shows the brain is capably of such distortion between self and non-self.
For the believer end of the genetic spectrum the experience can produce the illusion of voices, visions and the perception of paranormal powers; the culture, however, supplies the mythic framework around which the delusion takes form.
This phenomenon of human behavior is not limited to a belief in a supernatural deity , but extends to other areas of irrational thinking. Ancient alien contact, alien abductions, reincarnation, haunted places, curses, hexes, psychic powers, astrology and a dizzying array of other examples of irrational thinking; they are, most likely, a function of the same genetic makeup and brain chemistry/architecture.
A recent example of the power of the brain to switch its operating paradigm has been accounted by a number of astronauts.
Newburg is trying to discover, ”how to identify the markers of someone who has experienced space travel. He says there is a palpable difference in someone who has been in space, and he wants to know why. Newberg specializes in finding the neurological markers of brains in states of altered consciousness: Praying nuns, transcendental mediators, and others in focused or transcendent states”.
The transcendent state drifts into the fuzzy area of self/non-self and the ability to distinguish between the two. With the feeling of transcendent oneness and the limbic rewards of awe and pleasure, an individual could easily become addicted to their transcendent state of “holiness”.
In February, 1971, Apollo 14 astronaut Edgar Mitchell experienced the little understood phenomenon sometimes called the “Overview Effect”. He describes being completely engulfed by a profound sense of universal connectedness. Without warning, he says, a feeing of bliss, timelessness, and connectedness began to overwhelm him.
“Rusty Schweikart experienced it on March 6th 1969 during a spacewalk outside his Apollo 9 vehicle: “When you go around the Earth in an hour and a half, you begin to recognize that your identity is with that whole thing. That makes a change…it comes through to you so powerfully that you’re the sensing element for Man.”
The interesting thing about the “Overview Effect” is that it is not an overwhelming feeling of oneness with god, but rather, one of being god like.
One additional bit of evidence has raised some speculations on the historical “Giants of Religion” comes from Orrin Devinsky, who directs the epilepsy center at New York University.
“Some 2,500 years ago, Devinsky notes, Hippocrates wrote one of the very first texts we have on epilepsy — and he named it 'On the Sacred Disease.' The disease was considered sacred because the ancients thought that sufferers were possessed by demons, or blessed with divine messages and visions. Devinsky says neurologists suspect some of the religious giants were epileptics themselves. Did Paul hear Jesus on the road to Damascus, or was he experiencing an auditory hallucination? What about Joseph Smith and the two angels? Muhammad? Joan of Arc? And what about Moses and that burning bush?”
The “transcendent” mental state has been identified in brains scans that show a high level of activity in the parietal lobe. This information has been cited by theist as proof of god's communication with us by direct communication into our minds (souls?). Conversely, rationalist offer it as evidence that the transcendent, religious experience is simply a matter of genetics and the subsequent brain anatomy and chemistry .
All things considered, I think I have to concede the sad notion that the proclivity for irrational thinking among a great many members of the human species is an unfortunate part of our genetic heritage.
Genetics is a bitch to overcome – possible – but a bitch.