- At least 18,000 different gods, goddesses and various animals or objects have been worshipped by humans.
- Spirituality, or religiosity, has been mapped to a brain circuit that was centered on a brain region called the periaqueductal grey.
- This brain circuit, and the apparent importance of the periaqueductal grey, may have evolved to encourage altruistic behaviors and reduce fear.
Anthropologists estimate that at least 18,000 different gods, goddesses, and various animals or objects have been worshipped by humans since our species first appeared. Today, it is estimated that more than 80 percent of the global population considers themselves religious or spiritual in some form.
The neural substrates of religiosity or spirituality are under investigation by neuroscientists. Evolution has clearly selected a brain that can accept a logically absurd world of supernatural causes and beings. Spirituality must offer something tangible that enhances procreation and survival. Otherwise, evolution should have selected against such costly beliefs and behaviors as making gigantic pyramids to house the dead, blowing oneself up for the pleasures of paradise, or sacrificing one's children as a measure of devotion to one’s deity.
Religious beliefs, spirituality, and the need to worship a deity of some kind are undoubtedly durable traits. Some gods were worshipped for very long periods and then virtually disappeared from the historical record. For example, the sun god Ra was worshipped by many different cultures for thousands of years and then completely disappeared. If historical precedent holds, many of the gods worshipped today will be forgotten and quickly replaced by others.
During the past few years, neuroscientists have developed an area of study called the neuroscience of religiosity to understand the neurobiology of this fascinating aspect of human behavior.
The neural substrates of religious belief are an intriguing though contentious topic. Neuroscientists are often reductionistic and would like to explain religiosity by brain wiring. After all, the tendency to religiosity or spirituality and brain-wiring patterns that underlie specific personality traits are considered inheritable.
Are the brains of spiritual people different from those of atheists or agnostics?
One recent study used a collection of recently developed non-invasive tools to examine the brain and answer this question. The study used electroencephalography, structural neuroimaging (magnetic resonance imaging, MRI), and functional neuroimaging (both fMRI and positron emission technology) to study people who practiced a wide range of religions (e.g., Christianity, Buddhism, Islam). They were scanned and monitored while in religious or spiritual states or behaviors (e.g., simply resting, prayer, etc.).
The study had some inherent problems due to the challenge of measuring religiosity. Unique activity in several brain regions was associated with a religious or spiritual state, including areas of the frontal cortex, posterior cingulate cortex, and the default mode network. The findings suggest that the experience of being in a religious or spiritual state has specific neurobiological correlates and that these correlates are distinct from being in non-religious states.
A recent study attempted to map spirituality to a specific human brain circuit. The study discovered that self-reported spirituality or religiosity mapped to a brain circuit centered on a brain region called the periaqueductal grey. This is quite a fascinating discovery given that the periaqueductal grey is found in the brainstem, not the cortex, as might be expected from other studies.
The periaqueductal grey is an ancient structure that is believed to play a role in our response to fear, pain, and altruistic behavior. Damage to this brainstem circuit causes delusions, and alien limb syndrome also intersected this circuit. This brain circuit, and the apparent importance of the periaqueductal grey, may have evolved to encourage altruistic behaviors and reduce the fear of living in an unpredictable world.
Ferguson MA et al (2021) A neural circuit for spirituality and religiosity derived from patients with brain lesions. Biological Psychiatry 2021DOI:https://doi.org/10.1016/j.biopsych.2021.06.016
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