In 1955 I interrupted my teaching of anatomy for a year in order to teach physical anthropology at the University of Wisconsin. I had already been introduced to the subject of population genetics and at that time occasionally met with and discussed the subject with J. F. Crow and N. E. Morton. Back in Michigan the members of the Department of Human Genetics at the University of Michigan and other geneticists continued to stimulate these interests of mine. However, some of the mathematical models, which are common in population genetics, seem abstract and in my research I have preferred more comprehensible (even if somewhat less elegant) formulations when they are adequate to explain the empirical data. About two years ago, G. A. Harrison of the Department of Biological Anthropology at the University of Oxford expressed his pleasant surprise at how much interesting information on the structure of human populations had been garnered by studies of the distribution of surnames, and he suggested that I write a little book on the genetic structure of human populations as seen in this way. He implied that such a book should be directed at an audience who may not be at home with the erudite algebra of population genetics. I have therefore avoided discussion of some minor theoretical differences between mathematical models. Those who wish to pursue such issues will find additional definitions in the Glossary and appropriate references cited in the text.