Adoption of outgroup norms provides evidence for social transmission in perinatal care practices among rural Namibian women

Renée V Hagen; Brooke A Scelza

doi:10.1093/emph/eoaa029

Adoption of outgroup norms provides evidence for social transmission in perinatal care practices among rural Namibian women

Evol Med Public Health. 2020 Jul 30;2020(1):161-173. doi: 10.1093/emph/eoaa029. eCollection 2020.

Authors

Renée V Hagen^{1

2}, Brooke A Scelza^{1

2}

Affiliations

¹ Department of Anthropology, University of California, Los Angeles, CA, USA.
² Department of Anthropology, UCLA Center for Behavior, Evolution and Culture, Los Angeles, CA, USA.

Abstract

Background and objectives: How do new ideas spread in social groups? We apply the framework of cultural evolution theory to examine what drives change in perinatal care norms among Himba women in the Kunene region of Namibia. Access to formal medical care is on the rise in this region, and medical workers regularly visit communities to promote WHO-recommended perinatal care practices. This study investigates how various forms of social transmission affect women's uptake of medical recommendations concerning perinatal care.

Methodology: Based on interviews with one hundred Himba mothers, we used Bayesian multi-level logistical regression models to examine how perceptions of group preferences, prestige ascribed to outgroup conformers, interaction with the outgroup and access to resources affect norm adoption.

Results: Women who perceive medical recommendations as common in their group prefer, plan and practice these recommendations more often themselves. We observed a shift toward medical recommendations regarding birth location and contraception use that was in line with conformity bias predictions. Practices that serve as cultural identity markers persist in the population.

Conclusions and implications: Norm changes, and the cultural evolutionary processes that can lead to them, are not uniform, either in process or pace. Empirical studies like this one provide important examples of how these changes reflect local culture and circumstance and are critical for better understanding the models that currently predominate in cultural evolution work. These cases can also help bridge the gap between evolutionary anthropology and public health by demonstrating where promotion and prevention campaigns might be most effective.

Lay summary: The recent promotion of WHO-recommended perinatal care practices in Namibia provides an opportunity to empirically study norm change using a cultural evolution framework. We found women adopt medical recommendations when they believe these are common in their social group. Local norms that were not discouraged persisted in the study group.

Keywords: conformity bias; cultural evolution; non-WEIRD; norm change; norm intervention; reproductive health.