Migration rates of human populations from surname distributions.

Migration is an important factor in the biological evolution of human populations, and surnames provide one of the simplest records of identification. The distribution of surnames can supply quantitative information on the structure of human populations. Surnames considered as alleles of a gene transmitted only by the male line can be assumed to be neutral markers and therefore satisfy the expectations of the neutral theory of evolution, which is entirely described by random genetic drift, mutation and migration. As data on surnames are easier to collect than those from genes, the information yield is potentially increased, but the validity of the conclusions must be tested in actual samples. The purpose of this report is to compare the estimates of migration rates in Italy, as inferred by the surname distribution found in the telephone directories and other sources, with the corresponding estimates from official demographic sources. Our findings show that in these samples the ratio of surnames to individuals makes it possible to calculate reliable estimates of migration rates.