In this project I aim to develop a biogeographical framework for early hominin evolution in Africa, between ~5 and 2.5 million years ago. We hypothesize that recurrent climatically stable episodes, paced by eccentricity, caused recurrent riverine connections between coastal refuge areas and inland marginal areas, including the Chad Basin in West-Central Africa. To assess occurrence and timing of such East-West dispersal corridors, we use genetic distance between extant fish populations in Lakes Turkana and Chad as proxy for past hydrographic connectivity between these basins.