1. S. A. Tishkoff, W. Speed, A. J. Pakstis, J. R. Kidd, K. Cheung, and K. K. Kidd are in the Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520-8005, USA.
2. E. Dietzsch and T. Jenkins are in the Department of Human Genetics, School of Pathology, South African Institute for Medical Research, and University of the Witwatersrand, Post Office Box 1038, Johannesburg 2000, South Africa.
3. B. Bonné-Tamir is in the Department of Human Genetics, Sackler Faculty of Medicine, Tel Aviv University, 69978 Ramat Aviv, Israel.
4. A. S. Santachiara-Benerecetti is in the Buzzati Traverso Department of Genetics and Microbiology, University of Pavia, Via Abbiategrasso 207, 27100 Pavia, Italy.
5. P. Moral is in the Department of Animal Biology, University of Barcelona, Avinguda Diagonal 645, 08028 Barcelona, Spain.
6. M. Krings and S. Pääbo are at the Institute of Zoology, University of Munich, P.O. Box 202136, D-80021 Munich, Germany.
7. E. Watson is at the Institute of Zoology, University of Munich, Luisenstrasse 14, 80333 Munich 2, Germany, and School of Biological Sciences, Massey University, Palmerston North, New Zealand.
8. N. Risch is in the Department of Genetics, Stanford University Medical School, Stanford, CA 94305, USA.