Calculation of a mitochondrial DNA "clock" requires knowledge of an average generation time in a population or human ethnic group. Previous studies of the human mitochondrial DNA clock used a range of generation time estimates without any concrete knowledge of how generation times might vary by ethnicity. In this study, I document new data suggesting a historically faster generation time in Africans, which may explain why African people groups tend to harbor more mitochondrial DNA differences than non-African groups. These results underscore the biblical model of human origins in which the major ethnic groups originate simultaneously at the Tower of Babel event, and these findings simultaneously undercut the validity of the evolutionary out-of-Africa model.