Human Capacity for Religion through Natural Selection
The evolution of our species grew out of hunter/gatherer societies. The chances of these early societies surviving depended on their ability to cooperate. The benefits of group living that individuals attained through intragroup cooperation were cooperative hunting, food sharing, defense, and help raising the young. Despite the benefits of group living, these pursuits were often difficult to achieve if people seek to maximize their own personal gains. Humans had to trust that the other group members would invest as much time and energy hunting to make it worth their time risking their own safety to bring food home for the group. If this commitment to cooperation existed, intragroup cooperation was more likely to occur. Scientists believe that altruistic behavior was favored in early human settlements because it instilled trust and commitment between the groups. Some scientists theorize that human capacity for religion may have evolved to facilitate intragroup cooperation.
It is not surprising that groups of people who were able to successfully work together were able to provide more food and shelter for their family and raise more offspring. In this sense, communities who held high moral beliefs to protect and help each other had a higher chance of surviving and passing down their genes than those with selfish mindsets. William Irons, a Professor of Anthropology at Northwestern University, argues that some forms of human behavior have been favored over thousands of generations by natural selection and has resulted in our strong tendency to behave in these ways. He believes that the benefits of intragroup cooperation through natural selection could have favored a human psychology that facilitated religious beliefs and behaviors. Religion is a result of natural selection that favored individuals who adopted religious beliefs throughout our evolutionary history (Irons, 1991).
Most religions often include a series of rituals and expected behavioral patterns which act to signal commitment and loyalty to the group. This helps to prevent any free riding individuals who seek their own best interest by faking commitment to the group. Sacrifices, rituals, and expected behaviors such as refraining from premarital sex, work to increase the trust and strengthen the group, allowing for successful intragroup cooperation (Sosis, 2000). This has molded religion into an adaptive trait that helped the human species flourish.
The Co-Evolution of Humans and Religion
During the very early evolution of humans, very few reached old age. Looking at fossil records, the average expected lifespan was only 16 years and only 3 percent of humans lived to be 45-50 years old. Although early humans did not usually make it into their 20’s, the population was still able to be sustained as reproductive capability happens around ages 12-13 for females (Holliday, 200). The survival of these early groups was directly linked in their ability to cooperate and the incentive to adopt early altruistic behaviors was very high. As the more cooperative groups survived through natural selection, their life expectancy also increased. In the early stages of human evolution, ageing was not an expected consequence of survival. The increased life span led to greater, more developed brain size and the acquisition of more skills and knowledge. One of the greatest adaptations was the development of agriculture which allowed humans to have a more readily available food source.
As more and more people in a community survived into middle age and some surviving into old age, the existing moral codes for behavior changed. The reward for altruism and avoidance of self-interest was an increased chance of raising a family and having a longer adult life. At this point in time, the reward for group cooperation became old age and eventually death. This is believed by some scientists to be the birth of human religions that included an afterlife. The existing altruistic codes remained the same but the reward for virtue would be rewarded in an afterlife (Holliday, 2000). In today’s modern world people draw comfort from the belief in an afterlife and it is reasonable to believe that early humans when first faced with death from old age took the same comfort in believing there was more to life than just growing old and dying.
Holliday, Robin. 2000. Human Ageing and the origins of religion.Biogerontology. pg 73-77
Irons, William. (1996). Morality, religion, and human nature. In W. Richardson & W. Wildman (Eds.), Religion and science: History, method, and dialogue(pp. 375-399). New York: Routledge.
Sosis, Richard. 2000. Religion and Intragroup Cooperation: Preliminary Results of a Comparative Analysis of Utopian Communities. Cross-Cultural Research. Vol 34 pg 70-87