1. REHABS, International Research Laboratory, CNRS-NMU-UCBL, George Campus, Nelson Mandela University , George, 6529, South Africa
2. CIRMF, Centre Interdisciplinaire de Recherches Médicales de Franceville , Franceville, BP69, Gabon
3. Department of Anthropology, Durham University , South Road , Durham DH1 3LE, UK
4. Laboratory MIVEGEC, University of Montpellier, CNRS, IRD , 900 rue Jean François Breton, 34090 Montpellier, France