One of us (FMS) started to collect the information that was eventually incorporated in this book as early as 1956. In the ensuing years the compilation of the data continued, although not in a rigorously systematic way. Part of this information was used in the publication of a book about Brazilian populations in 1970, and the editing of another about Latin America in 1971. In more recent years the data collection became more systematic, and at the beginning of 1998 MCB started to help with the data analysis. In these three years in which we have been more specifically involved in the book's development much work was done, but with considerable enjoyment. Latin America's cultural, political and biologic histories make a fascinating subject, and we do not regret the decision, at least superficially, to describe and interpret them.

Naturally, the analysis of such a wide area and large population may have resulted in several gaps and involuntary omissions. Since our area of expertise is population genetics, the coverage of this aspect was much more complete than in the other subjects covered by the book, such as archeology, history, demography, biologic and social anthropology, or medicine. But since we believe that evolutionary studies in humans should be as comprehensive as possible, we decided to include them even at the risk of incurring such faults. Some friends helped by reading the different chapters and providing precious advice. They are as follows: 1. Origins: Marta M. Lahr (University of São Paulo, Brazil, and University of Cambridge, UK); 2. Environment and history: Claudia Wasserman (Federal University of Rio Grande do Sul, Brazil); 3. Socioeconomic indices, demography, and population structure: Juan Pinto (University of Valparaiso, Chile); 4.