Gona in Ethiopia, and Ain Hanech (including Ain Boucherit) and Tighennif in Algeria, are three of the most important Palaeoanthropological research areas for investigating the biological, behavioural and cognitive evolution of Early Pleistocene human ancestors. The Gona archaeology, dated to 2.6 million years ago (Ma), represents the earliest Oldowan, and those from Ain Hanech dated to ~2.4 Ma, are currently the earliest in North Africa. The fossil-bearing deposits at Gona stretch back to >6.0 Ma, with the discovery of a large number of hominins (Ardipithecus kadabba ~6.0 Ma, and Ar. ramidus ~4.5 Ma). Further, Gona has produced early Homo erectus crania (1.5 and 1.26 Ma, respectively) associated with Oldowan and Acheulian artifacts. Similarly, the fossil-bearing deposits at Ain Hanech date back to 2.4 Ma, but hominins have yet to be found in the Oldowan and Acheulian-bearing layers (~2.4-1.6 Ma), although in the 1950s Tighennif has produced H. erectus mandibles and a parietal associated with the Acheulian ~1.0-0.8 Ma.
Ain Hanech site
Unique to both Gona and Ain Hanech is the fact that both sites contain stone artefacts showing technological advances in the 2.6-2.0 Ma time interval, which is seen only ~1.8 Ma or later elsewhere in Africa. The earliest Homo in Africa is dated to ~2.8 Ma, with the next set of early Homo fossils known only ~2.5-2.3 Ma, leaving the critical time interval ~2.3-2.0 Ma void in terms of hominin fossil record. Also, archaeologically little is known ~2.3-2.0 Ma. This totally unknown time interval (~2.3-2.0 Ma) needs focused multi-disciplinary field investigations, as it is clear now (i.e. based on the 1.85 Ma Oldowan artefacts documented at Dmanisi, in the Republic of Georgia) that the immediate ancestor of H. erectus must have left the African continent ~2.0 Ma or earlier, and prior to the emergence of the Acheulian. As a result, it remains unclear whether or not early Homo (H. rudolfensis/H. habilis) and H. erectus/ergaster are time-successive species or lived side-by-side (i.e. 2.0-1.5 Ma). The Gona and Ain Hanech Early Pleistocene deposits complement each other, and with proven record for providing unique opportunity for investigating the behavioural and biological evolution of our ancestors ~2.6-0.2 Ma. Thus, continued multi-component field investigations are warranted at Gona and Ain Hanech to unravel the 2.6 million-year evolutionary advances made by our ancestors.
Sileshi Semaw at Gona site