Hominin evolution and dispersal patterns in the East African Rift System were controlled by groundwater availability according to a study published in Nature Communications this week. The research shows that groundwater acted as a buffer to climate variability in the region by providing a source of fresh water in the form of natural springs.
The East African Rift System represents an active continental rift, currently forcing apart Africa, that is a key location for the evolution of Homo sapiens. Hominin evolution and dispersal in the region had been previously assumed to be solely dependent on climate shifts. However, it was not previously understood what sources of fresh water were available when the climate was very dry and, therefore, how and where hominins could have survived and dispersed during such times.
Mark Cuthbert and colleagues mapped the current landscape in the East African Rift System, identifying over 450 current springs, to produce a model of how groundwater distribution varies with climate. They coupled these data and models with modelling of hominin movements. The authors found that in dry periods, groundwater availability was critical in supporting isolated habitats where surface water was scarce. Thus, groundwater sources may have facilitated unexpected variations in the dispersal and survival of hominin populations in the East African Rift System.