Parasite-stress promotes in-group assortative sociality: the cases of strong family ties and heightened religiosity

Fincher, C.L. and Thornhill, R. (2012) Parasite-stress promotes in-group assortative sociality: the cases of strong family ties and heightened religiosity. Behavioral and Brain Sciences, 35(2), pp. 61-79. (doi: 10.1017/S0140525X11000021)

Abstract

Throughout the world people differ in the magnitude with which they value strong family ties or heightened religiosity. We propose that this cross-cultural variation is a result of a contingent psychological adaptation that facilitates in-group assortative sociality in the face of high levels of parasite-stress while devaluing in-group assortative sociality in areas with low levels of parasite-stress. This is because in-group assortative sociality is more important for the avoidance of infection from novel parasites and for the management of infection in regions with high levels of parasite-stress compared with regions of low infectious disease stress. We examined this hypothesis by testing the predictions that there would be a positive association between parasite-stress and strength of family ties or religiosity. We conducted this study by comparing among nations and among states in the United States of America. We found for both the international and the interstate analyses that in-group assortative sociality was positively associated with parasite-stress. This was true when controlling for potentially confounding factors such as human freedom and economic development. The findings support the parasite-stress theory of sociality, that is, the proposal that parasite-stress is central to the evolution of social life in humans and other animals.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Fincher, Dr Corey
• Authors: Fincher, C.L., and Thornhill, R.
• College/School: College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
• Journal Name: Behavioral and Brain Sciences
• Publisher: Cambridge University Press
• ISSN: 0140-525X
• ISSN (Online): 1469-1825
• Published Online: 31 January 2012
• Copyright Holders: Copyright © 2012 Cambridge University Press
• First Published: First published in Behavioral and Brain Sciences 35(2):61-79
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher