Tectonic and Paleoclimatic Setting for Hominin Evolution in Eastern Africa

Abstract

As dynamic processes in the Earth’s mantle stretch and thin large sectors of the African plate, broad plateaus interrupted by deep valleys and flanking mountains have formed at the Earth’s surface. These vertical and horizontal crustal movements occur concurrent with global climate changes, both of which happen over diverse spatial and temporal scales. Together, they modulated eastern Africa’s habitats for early hominins, and for flora and fauna in general. The habitat for hominin evolution, therefore, is shaped by bottom-up and top-down processes. Broad plateau uplift in Ethiopia had initiated by 30 Ma, coincident with or after flood magmatism at 45 Ma when dry seasonal woodland environments initiated in eastern Africa. The fossil-rich sedimentary sequences partially filling the 30–70-km-wide rift basins record the history of human evolution, as well as the complex interplay between climate change, uplift, volcanism, and faulting in equatorial Africa. The lake shorelines and hydrothermal systems served as oases for hunter-gatherers, and the rough topography of the faulted landscape may have served as refugia. Here, we outline the relevant time–space patterns to establish the geodynamic and paleoclimatic context for human evolution in eastern Africa.