This paper establishes that the worldwide distribution of political instability has its deep historical roots in genetic diversity, predetermined over the prehistoric course of the exodus of Homo sapiens from East Africa tens of thousands of years ago. It proposes that the relationship between prehistorically determined genetic diversity and contemporary political instability follows a U-shaped pattern. More specifically, genetic diversity at first reduces the persistence of political instability by increasing the opportunity cost of engaging in riots and revolts. However, genetically fragmented societies tend to suffer from interpersonal mistrust and the under-provision of public goods, which plausibly undermine the establishment of politically stable regimes. Using an ancestry-adjusted index of predicted genetic diversity, this paper consistently finds precise estimates that genetic diversity imparts a U-shaped influence on different measures of political instability and the probability of observing the occurrence of riots and revolts across 141 countries. Furthermore, the contribution of genetic diversity to political instability is at least partially mediated through income/productivity levels, the provision of public goods, income inequality and social trust.