1. Population Research Institute and Department of Anthropology, Pennsylvania State University, University Park, PA 16802
2. Centre for Health and Social Policy, Odense University, Odense DK-5000, Denmark
3. Department of Anthropology and Graduate Program in Genetics, Pennsylvania State University, University Park, PA 16802
4. Department of Demography, Georgetown University, Washington, DC 20057
5. Taiwan Provincial Institute of Family Planning, Taichung 400, Taiwan Republic of China