The cradle of mankind The system of rift valleys that characterizes the African continent represents a perfect environment to understand the evolution of mankind; for the important paleoanthropological discoveries in Ethiopia, Kenya, Tanzania, Uganda and Zaire, the African rift valleys are indeed considered the "cradle of mankind", that is the place where our species evolved and diversified in the last million years.

The association between paleoanthropological discoveries and rift valleys is not accidental, since the volcanic and tectonic activities that gave rise to the tectonic depressions and the contemporaneous accumulation of sediments in the basins created the ideal conditions for the proliferation of life. In parallel, lavas, volcaniclastic sediments, and tephra were responsible for the quick burial and preservation of faunal and floral remains. Many extremely well-preserved human and animal fossils have been found in the Ethiopian rift valley, suggesting that this area may have represented a crucial site for human evolution in the last million years. In particular, some Ethiopian localities are of great importance for paleoanthropological researches: for instance, fossils from the Middle Valley of the Awash river bear witness of the whole hominid evolution, from 6 million years to the present. Paleoanthropological sites in Ethiopia (Click to enlarge) fossils of the middle awash (click to enlarge) Among the most important findings: -Ardipithecus, and in particular fossils of Ardipithecus kadabba (dated between 5,54 and 5,77 million years b.p.) and Ardipithecus ramidus (dated between at 4,4 million years b.p); -Australopithecus, and in particular fossils of Australopithecus anamensis (dated at around 4.1 million years b.p.), Australopithecus afarensis (the most famous fossil of this species is the partial skeleton named Lucy -3.2 million years old- found by Donald Johanson and colleagues at Hadar in the Awash Valley) and later species (A. africanus, A. garhi); -genus Homo, and in particular fossils of Homo habilis (dated at 2.3 million years b.p.), Homo erectus (differentiated from Habilis at around 1,5 million years b.p.), Homo sapiens (fossils dated at around 155,000 years b.p.). fossil localities in the middle awash (click to enlarge) The transition between Homo erectus and the subsequent Homo sapiens is still highly debated. The most accepted theory suggests that the Homo sapiens differentiated from the erectus in Africa; subsequently, Homo sapiens would have given rise to a sub-species, the modern Homo sapiens sapiens, able to migrate (at around 60,000-70,000 years b.p.) out of Africa and to colonize the other continents substituting other local, more primitive populations (such as the Homo neanderthalensis in Europe).

