It has been known for some time that religious belief and behavior affect the brain—in the same way all habits, emotions and memories build neural pathways. But can we pinpoint specific chemicals, genes and clusters of neurons that give rise to religiosity, or to atheism?
Rutgers University evolutionary biologist Lionel Tiger thinks we can: “Religion is really made by the brain. It is a secretion of the brain,” says Tiger, who thinks the root of religious belief is an evolutionary drive to seek this “secretion”—namely serotonin—which provides the believer with feelings of well-being. A neurotransmitter that regulates mood and appetite, serotonin is linked to feelings of well-being when it floods the central nervous system.
“One of the ways of looking at religion is to what extent and how does it generate the serotonergic juices that make us feel good,” says Tiger. Attending a religious service, for example, can be a flurry of social activity and controlled procedure, which releases a cocktail of serotonin-led neurotransmitters in the brain. This chemical response “soothes” the organ, he says, echoing the results of recent studies. Working with neuroscientist Michael McGuire, Tiger has connected this research on serotonin as it works in the brain with the social aspects and origins of religion.
“Religion may be one of the main producers of the brain-soothing phenomenon in a way that is not that expensive or destructive or difficult. All you have to do is show up Sunday morning,” Tiger says. Religion, in this sense, becomes a self-created, self-consumed endeavor, he adds.
Tiger’s conclusion is that the neurochemical response of religion serves a biological need for humans, as shown in its absence. As an example, he points to France, a nominally Catholic country with low mass attendance and rare religious observance that has one of Europe’s highest rates of antidepressant consumption. “It may be that they’re taking the mass into their skull with a pill, so there is the pharmacological element of brain soothing,” he says.
Yet, religion is not all soothing, and serotonin itself cannot account for bouts of religious ecstasy and visions from—in Christianity alone—Pentecostal glossolalia and the charismatic movement stretching all the way back to Saul’s dramatic conversion on the road to Damascus.
To get to the root of religious zeal, scientists are looking beyond neural chemistry to the architecture of the brain itself. There isn’t one part of the brain dedicated to processing the divine, as the pineal gland was once thought to be the seat of the soul. Instead, according to recent research, religiosity is dislocated and strung out along a neural network comprised of the frontal, parietal and temporal lobes.
Decreased parietal lobe activity, for example, has been linked to some religious experiences, while the decision-making and social aspects of religion seem to interplay in the frontal lobes. It is the temporal lobes that have been the focus of significant recent interest for their connection between epilepsy and religious visions and conversion. Epileptic seizures, and the brain chemistry at work between seizures, leads in some patients to a “gradual personality change which disposes them to mystical and religious thinking,” says neurologist Oliver Sacks in an interview with Big Think.