Religion: Spandrel of the Brain? The Evolutionary Psychology of Religion

During the last decades, research into the biological origin of religion has gained considerable momentum. Religiousness has been shown to be heritable – though only to a moderate extent – which has prompted various scholars (e.g. D.S. Wilson, R.D. Alexander) to argue religion is an adaptation: a genetically inherited trait that increases fitness. However, as Stephen J Gould has forcefully argued, not all inheritable traits need be adaptations; in various ways traits can emerge and persist in evolution without increasing fitness per se. In this literature study, I explore the possibility that religion is not an adaptation, but exists for different reasons. Non-adaptive traits can persist as by-products of adaptive traits. A number of scholars (P. Boyer, L. Kirkpatrick, S. Atran, S.J. Mithen, S. Guthrie) have argued religion qualifies as a by-product of cognitive hardware. In their view, religious thought and behavior is produced by various brain mechanisms that in themselves are adaptive. These were preserved in evolution because they solved particular (non-religious) problems faced by our ancestors. Byproduct theories of religion provide an interesting and plausible alternative to their adaptationist counterparts: they are capable of explaining the full spectrum of religious manifestations, without invoking any function for which they were selected. Five million years ago, the evolutionary paths of man and chimpanzee separated: our last common ancestor eventually gave rise to a distinct human ancestor – Australopithecus – and an ‘ancestral’ chimpanzee. In the period to follow, the ape-like Australopithecus came to evolve into the modern Homo sapiens sapiens; selection pressures over the last five millions years gave rise to all traits commonly considered uniquely human (e.g. language, culture). What were these selection pressures like? Many have argued that our ancestor most prominently was under great pressure to organize: formation of ever-larger groups would have been indispensable for coordinated huntingand gathering expeditions, and defense against predators (animals, but also other human groups). To enable increases in group size, our brain has become strongly focused on other humans: it ascribes them beliefs, intentions and emotional states, feels their pain, shares their moral codes, and watches closely if others adhere to such codes. In fact, the human brain has become so strongly focused on humans that it quite easily perceives humans when there are none: any inexplicable phenomenon, any single or remarkable event is ascribed to human agents. In addition, the new cognitive hardware for active reasoning about other humans tends to over-activity: it fails to shutdown when observing familiar corpses (thus leaving the brain with the concept of a bodiless human agent), and prefers to represent the subconscious self as beliefs and intentions of others. As a result, the brain cannot help but observe an environment flooded with (signs of) powerful, invisible supernatural agents. Given the means through which it does so, it is not surprising that the brain holds quite elaborate assumptions on the nature of such agents: they are thought powerful, invisible or acting remotely, and involved in social exchange (and hence, to a certain extent manageable – one could achieve something by engaging in social interaction with the supernatural). Summarizing, the brain inadvertently develops the notion of relevant supernatural agents: certainly an ideal starting point for religious thought and practices. Five million years