1. Division of Exercise Science and Sports Medicine, Department of Human Biology; University of Cape Town; Cape Town South Africa
2. Early Start and School of Education; University of Wollongong; Wollongong NSW Australia
3. Department of Experimental Psychology; University of Oxford; Oxford UK
4. MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences; University of the Witwatersrand; Johannesburg South Africa
5. Umeå Centre for Global Health Research, Umeå University; Umeå Sweden
6. MRC/Wits Developmental Pathways for Health Research Unit, Faculty of Health Sciences; University of the Witwatersrand; Johannesburg South Africa