Two areas of research in human molecular population genetics are proposed. The first entails statistical and mathematical analysis of molecular variability in samples taken from a worldwide array of population. The molecular variation includes polymorphisms in short tandemly repeated DNA, also called microsatellites, and single nucleotide polymorphisms on the autosomes and X and Y chromosomes. Single nucleotide variation in microsatellite data whose values reflect the history of population expansion or contraction. Genealogical approaches will also be developed to analyze Y-chromosomal and mtDNA haplotypes, giving estimates of the rates of population growth as well as the time since the most recent common ancestral haplotype. Estimates obtained from microsatellite data and single nucleotide variation will be compared. Linkage disequilibrium in haplotypes will be used to estimate the amount of migration. Data from wild ancestors of cultivated wheat, barley, and chickens will be compared with data from domesticated varieties to give estimates of the time of human cultivation of these important species. In the second area of research, we will investigate measures of disease association, population stratification, and admixture using case-control studies. We will use a statistical method to determine from multi-locus genotypes whether a case-control sample is subject to population stratification. We will also derive statistical tests of association, based on case-control studies, that can be used when the population is stratified, and investigate the power of these tests. Using multi-locus genotypes and likelihood analysis, we will develop a method to identify the population(s) of origin from individuals of unknown ancestry.