Science on Religion

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Religion may have evolved to maximize inclusive fitness

Family sunsetReligion continues to be a topic of fierce debate among evolution researche. Some argue that religion evolved because it offers a real evolutionary advantage over religionless rival tribes (for example, by strengthening social bonds). Others retort that religion merely hijacks advantages that actually evolved for non-religious reasons. Taking sides in this debate, biologists Bernard Crespi (Simon Fraser University, Canada) and Kyle Summers (East Carolina University) argue that religion, and with it the idea of “God,” evolved to increase the fitness of in-groups and kin.

The researchers make several points to support their argument. They start by considering a pre-religious tribal culture. In this culture, the most fit have the greatest chances of survival and reproductive success. Siblings, then, will battle each other over their parents’ resources in order to gain an advantage not only over their rival siblings but also over other people in the tribe. From the parents’ perspective, they want their children to succeed and will invest resources in them, but will also reach a point where their children demand more than their parents can give.

At this point, religion could provide a way forward. Religion, according to the biologists, originated from abstracting familial relationships. They argue that in primitive languages one can easily transition, for example, from “Grandfather wanted...” to “Grandfather wants....” In other words, in such a language the dead can readily become present and alive, leading to a belief in an afterlife. Over time, after a belief in an afterlife becomes common, the revered ancestors could transition into gods. Since at this point the deceased would be a relative of many people, the word “god” effectively acts as a metaphor for the circle of kin. Finally, the word “god” comes to be interpreted literally, resulting in the various religions that exist today.

By gods really standing as metaphors for family members, religion binds families together, making familial relations a sacred priority. This means that while siblings demand resources from their parents, they in turn must give resources back to their parents and also to their fellow siblings. Religion transforms the standard evolutionary “survival of the fittest” into something more akin to “survival of the fittest family.” That is, religion makes evolution family-oriented, giving that family a resource advantage. Religion provides a further advantage by enforcing “good behavior” by following the precepts of the gods, who really are their own ancestors (in contrast to pure fiction, which focuses on building a society or culture as a whole rather than on family).

Eventually, the morality and religious beliefs and behaviors of a family will spread to other families in the tribe. The authors point out that in hunter-gatherer, horticultural, and pastoral societies, the spread will occur seamlessly because of the already tight-knit social networks and because of arranged marriages. If a society ceases to follow the practice of arranged marriage, or if it grows so large that ethnic kinship no longer can persists, then religious diversity will emerge.

As a final piece of evidence, the biologists refer to research that suggests a link between oxytocin in females and vasopressin in males as neuropeptides that mediate religiosity. These neuropeptides correlate with increased trust, generosity, kinship recognition, social rituals (including dance and music), as well as feelings of warmth, cooperation, and good will. In other words, the same chemicals that correlate with pro-social and pro-family behavior also correlate with religious belief.

Obviously, not every evolutionary biologist will agree with the authors’ argument. Some would argue instead that all of the social benefits that evolved did so without religion, and religion only appeared on the scene afterward, usurping these social benefits. No one can be sure where the dust will settle, but the debate will certainly continue to evolve.

For more, see “Inclusive fitness theory for the evolution of religion” in the journal Animal Behaviour.

 

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