While media excitement about the supposed discovery of a single “God module” in the brain has rightly followed scientific consensus and cooled off considerably, the more general idea that religious thoughts, feelings, and experiences are realized by specific regions of the brain remains a suggestive hypothesis. For example, if variations in the density of brain regions can be associated with memory loss, then why wouldn’t we see a similar correlation with religion? Not surprisingly, researchers have recently found links between religion and regional cortical volume.
In a study conducted by Dimitrios Kapogiannis, Aron K. Barbey, Michael Su, Frank Krueger, and Jordan Grafman, variability in important measures of religiosity was associated with differences in cortical volume. Researchers began with the reasonable hypothesis that “religiosity . . . is modulated by neuroanatomical variability.”
This basic hypothesis was tested by looking for correlations between variations in regional cortical volume and four “Principle Components of religiosity” determined by analyzing survey data from test subjects. The Principle Components of “religiosity” were (PC1) experiencing an intimate relationship with God, (PC2) religiosity of upbringing, (PC3) (non-)religious pragmatism, and (PC4) experiencing fear of God’s anger. While these “principle components” do not represent a wide range of religious concerns (how would a Buddhist for example be measured on these principles?) they are certainly among those elements that would be included in most assessments of “religion,” especially Western monotheistic religion. Cortical volume was determined through structural magnetic resonance imaging using voxel-based morphometry.
Here is a summary of the study’s findings:
PC1 was “positively correlated with the volume of BA 21 at the R[ight] middle temporal gyrus (MTG) and its extension at the temporal pole.” That is, subjects who reported an intimate relationship with God tended to have increased volume in this region of their brain. The R MTG has been linked to aspects of intimate interpersonal relationships, leading researchers to conclude that “by evolution of this area and its connections, a personal relationship with God as an intimate other may have become possible, allowing modern humans to experience this bonding….”
PC2 was not correlated to the cortical volume of any brain area. Apparently, the religion of one’s upbringing has no impact on volume of one’s cortex. This finding seems to suggest that the correlations discovered in this study are the result of biological variations that are expressed in religious belief and not the result of the effects of religious cognitions on neuroanatomy. However, since this study rests on mere correlation, causal relationships cannot be determined on the basis of its findings.
PC3 positively correlated to the volume of the right precuneus (BA 7) and the right calcarine gyrus (BA 17). That is, subjects with a higher volume in these areas tend to approach moral and religious issues with more skepticism and pragmatism. The right precuneus has been linked to “enhanced ability to switch between different perspectives to address moral dilemmas.” The researchers “speculate that people with increased R precuneate volume may also place an emphasis on worldly experiences over the inner life of imagination,” leading to a less “religious” worldview.
PC 4 correlated negatively with the cortical volume of the left precuneus (BA 7) and the left orbitofrontal cortex (BA 11). In other words, subjects with lower volume in these areas experienced more fear in their relationship with God. BA 11 is an area “associated with our ability for emotion-related ToM [Theory of Mind] (also termed cognitive empathy).” “People with lower cortical volumes in Bas 7 and 11 may be prone to a fear-based approach to God because of being compromised in representing the intentions and emotional disposition of God….”
Kapogiannis et al. suggest that since the areas identified by their study as significant for religiosity “are not unique to processing religion . . . religious beliefs and behavior emerged not as sui generis evolutionary adaptations, but as an extension (some would say “by product”) of social cognition and behavior.”
See here, for the full text of the article, “Neuroanatomical variability of religiosity,” PLoS One 4(9): e7180. Doi:10.1371/journal.pone.0007180.