Hypervariable parts of mitochondrial DNA (mtDNA) were amplified enzymatically and sequenced directly by using genomic DNA from single plucked human hairs. This method has been applied to study mtDNA sequence variation among 15 members of the !Kung population. A genealogical tree relating these aboriginal, Khoisan-speaking southern Africans to 68 other humans and to one chimpanzee has the deepest branches occurring amongst the !Kung, a result consistent with an African origin of human mtDNA. Fifteen cases of unrelated individuals having identical sequences in the most variable parts of the mtDNA control region were found within populations of !Kung, Western Pygmies, and Eastern Pygmies, but no cases of identity were evident among these populations. This and other evidence of geographic structuring of the mitochondrial diversity in Africa, together with knowledge of the rate of accumulation of base changes in human mtDNA, implies that the average rate at which female lineages have moved their home bases during hunter-gatherer times could be as low as 13 meters per year. The technique of enzymatic amplification and direct sequencing applied to readily collected, highly stable biological materials such as hairs makes it possible to examine with high resolution many representatives of virtually any population.