Evolution, Sexuality, and Religion: Toward a Multi-level Model of the Emergence of Religion James A. Van Slyke Southern California Working Group on Culture, Cognition, and Religion February 19, 2011

Religion By-Product or Adaptation? By-product theory – Religion is a secondary, unintentional by-product of cognitive adaptations designed for other functions Adaptation theory – Religion serves some type of adaptive function in promoting reproductive success and survival in evolutionary history

Religion: By-Product and Adaptation Religion is a very diverse and complex phenomena Different aspects of religion evolved as a consequence of both factors Multi-level Approach – Cognitive factors – Individual level factors – Group level factors

Cognitive Factors and the Evolution of Sexuality Evolutionary Psychology – Cognitive adaptations for sexual preferences in mate selection – Adaptive to have preferences that increased reproductive success WHR (Waist to Hip Ratio) Facial Symmetry

Religion & Sexuality Sexuality is a common component in religious symbols – Many ancient cultures intertwined sexuality with religious rituals – Statues and other artifacts depict various forms of sexuality Medieval Hindu and Jain Temples in India

Evolution of Cooperation Reciprocal Altruism (Trivers 1971) – Acts may be offered to another if there is reasonable expectation of reciprocation – Need to discriminate between cooperators and cheaters Indirect Reciprocity (Alexander 1987) – Reputation as a reliable partner may also facilitate the development of alliances

Costly Signaling Theory (Atran, Sosis, Bulbulia) Religion serve as a proxy for detecting trustworthy partners – Higher individual costs in religious behavior signal higher potential for reciprocal exchange and cooperation – Higher religious commitment correlated with longevity in religious communities (Sosis & Bressler 2003) – Priming with God concepts increases monetary payments in economic game (Shariff & Norenzayan 2007)

Religion as a Signal in Sexual Selection Religion used to estimate mate faithfulness – Among the Utila, men prefer woman who demonstrate piety (Bulbulia 2008) – Men do not attend religious services Religious commitment increases in the presence of competitors – Higher levels of religiosity reported after viewing attractive people of the same sex (Li et. al. 2010)

Group-Level Adaptation David Sloan Wilson (2002) – If there are several groups in a population, variation in regard to an adaptive trait may increase benefits for one group – Religion evolved as a an adaptive set of moral constraints on individual behavior Monitors social life in reciprocity Means of punishment for cheaters Motivation for certain behaviors Defines in-group vs. out-group

Group-Level Adaptation Religion evolved at the group level to regulate individual sexual selection – Religious mores and values often directed at sexual activity – Provides a means for regulating sexual activity among a group – Evolved as a way to balance individual interests with group interests

Religion and Mating Strategy Moral views about sexual behavior related to religious affiliation – Survey of 21,000 US residents, sexual behaviors were the best predictor of religious attendance (Weeden et. al. 2008) – Religion may promote a particular mating strategy Low promiscuity (Paternity assurance) Marriage centered High Fertility (increased marital and social support)