The Editors : Claudine Sauvain-Dugerdil, Director of the Laboratory of Demography and Family Studies, University of Geneva, Switzerland. Henri Leridon, Head of the Research Unit on Reproduction of INSERM (Institut National de la Santé et de la Recherche Médicale) / INED (Institut National d'Etudes Démographiques), Paris, France. Nicholas Mascie-Taylor, Head of the Department of Biological Anthropology, University of Cambridge, UK.