The rift systems of Ethiopia, Kenya and Tanzania, and the limestone caverns near Johannesburg, South Africa have a long history of intensive archaeological study, rewarded by many finds of hominin skeletal remains and artifacts over the last century. Each region lays claim to be the birthplace of humans, that in South Africa being grandiloquently dubbed ‘The Cradle of Humankind’. Of course, the realistic chances of making discoveries and careers draws scientists and funds back to these regions again and again: a kind of self-fulfilling prophesy fueled by the old miners’ adage, ‘to find elephants you must go to elephant country’. The key site for the earliest stone tools was for a long time Tanzania’s Olduvai Gorge, thanks to finds of deliberately shaped choppers, hammer stones and sharp edges from about 2 Ma ago in close association with remains of Homo habilis by the Leakeys. Termed ‘Oldowan’, signs of this industry emerged from 2.6 Ma sediments in the Afar Depression of Ethiopia in 2010, but with no sign of who had made them. By 2015 the cachet of ‘first tools’ moved to Lomekwi on the shore of Lake Turkana in Kenya, dated to 3.3 Ma but again with no evidence for a maker. In fact the oldest evidence for the use of tools emerged with the 2010controversial discovery at Dikika in Afar of 3.4 Ma old bones that carry cut marks, but no sign of tools nor whoever had used them. However remains of Australopithecus afarensis occur only a few kilometers away.
Excavations outside the East African Rift System and South Africa are still few and far between, especially from before 1 Ma. The High Plateaus of eastern Algeria include one ancient site, near Ain Hanech, which yielded 1.8 Ma Oldowan stone artifacts as long ago as 1992. A nearby site at Ain Boucherit takes the North African record back to 2.4 Ma with both Oldowan tools and cut-marked bones of horse and antelope (Sahnouni, M. and 12 others 2018. 1.9-million- and 2.4-million-year-old artifacts and stone tool–cutmarked bones of from Ain Boucherit, Algeria. Science, v. 362, p. 1297-1301; DOI: 10.1126/science.aau0008). Tool makers had clearly diffused across what is now the Sahara Desert by that time. Given the distance between the Lomekwi and Dikika sites in East Africa that is hardly a surprise, provided climatic conditions were favourable. Michel Brunet’s discovery in 3.3 Ma old sediments of an australopithecine (Au. bahrelghazali) in central Chad demonstrates that early hominins were quite capable of spreading across the African continent. Yet, to wean palaeoanthropologists and their sponsors from hitherto fruitful, ‘elephant’ areas to a more ‘blue skies’ approach is likely to be difficult. There are plenty of sedimentary basins in Africa that preserve Miocene to Recent sediments that may yet turn up fossils and artifacts that take the science of human origins and peregrinations further and possibly in unexpected taxonomic directions
Related article: Gibbons, A. 2018. Strongest evidence of early humans butchering animals discovered in North Africa. Science News online; doi:10.1126/science.aaw2245.
Read more on Human evolution and migrations