The oldest evidence of geophagia practised by humans comes from the prehistoric site at Kalambo Falls on the border between Zambia and Tanzania (Root-Bernstein & Root-Bernstein, 2000). Here, a calcium-rich white clay was found alongside the bones of Homo habilis (the immediate predecessor of Homo sapiens). — Peter Abrahams, Geophagy and the Involuntary Ingestion of Soil[5]:446