Why are so many early human fossils found in East Africa?
“The final question is about the extent of sampling of the fossil record. We have to accept that the ‘sampling’ of fossils in Africa is totally inadequate to gain an idea of what kind of ancestral animals were there, where they lived, and for how long. Fossils have been found mainly where huge rifts in the ground have exposed ancient strata, or where limestone caves or holes exist where animals might fall and fossilise. In addition, the soils must contain alkali compounds such as calcium carbonates and phosphates to mineralise and preserve bone. These special conditions self limit mainly to the rift valley system and soils of Kenya, Tanzania, Ethiopia, and a few favorable sites in Southern Africa (in limestone formations, or ancient sand covered inland fossil beaches). Huge areas of Central and Southern Africa yield no fossils, both because the soils are leached and acidic (in lateritic soils beneath rainforest, typically pH 4.5 to 5.5) and destroy bone, and because what fossils might
