1. Department of Sociology, School of Public and International Affairs, and the Office of Population Research, Princeton University, Princeton, NJ, USA
2. MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), Faculty of Health Sciences, School of Public Health, University of the Witwatersrand, South Africa
3. Department of Sociology, American University, Washington, DC, USA
4. Social and Behavioral Sciences, Soka University of America, Aliso Viejo, CA, USA
5. Department of Public Health and Department of Women’s & Gender Studies, University of Missouri and MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), Faculty of Health Sciences, School of Public Health, University of the Witwatersrand, South Africa