In Africa, several early (around 200,000– 100,000 ya) fossils have been interpreted as fully anatomically modern forms . The earliest of these specimens comes from Omo Kibish, in southernmost Ethiopia. Using radiometric techniques, redating of a fragmentary skull (Omo 1) demonstrates that, coming from 195,000 ya, this is the earliest modern human yet found in Africa—or, for that matter, anywhere else (McDougall et al., 2005). An interesting aspect of fossils from this site concerns the variation shown between the two individuals. Omo 1 is essentially modern in most respects , but another ostensibly contemporary cranium (Omo 2) is much more robust and less modern in morphology.
Somewhat later modern human fossils come from the Klasies River Mouth on the south coast of Africa and Border Cave, just slightly to the north. Using relatively new techniques, paleoanthropologists have dated both sites to about 120,000–80,000 ya. The original geological context at Border Cave is uncertain, and the fossils may be younger than those at Klasies River Mouth. Although recent reevaluation of the Omo site has provided much more dependable dating, there are still questions remaining about some of the other early modern fossils from Africa. Nevertheless, it now seems very likely that early modern humans appeared in East Africa by shortly after 200,000 ya and had migrated to southern Africa by approximately 100,000 ya.
More recently discovered fossils are helping confirm this view. Herto :The announcement in 2003 of well-preserved and well-dated H. sapiens fossils from Ethiopia has gone a long way toward filling gaps in the African fossil record. As a result, these fossils are helping to resolve key issues regarding modern human origins. Tim White, of the University of California, Berkeley, and his colleagues have been working for three decades in the Middle Awash area of Ethiopia. They’ve discovered a remarkable array of early fossil hominins (Ardipithecus and Australopithecus) as well as somewhat later forms (H. erectus). From this same area in the Middle Awash, highly significant new discoveries came to light in 1997. For simplicity, these new hominins are referred to as the Herto remains.
These Herto fossils include a mostly complete adult cranium, an incomplete adult cranium, a fairly complete (but heavily reconstructed) child’s cranium, and a few other cranial fragments. Following lengthy reconstruction and detailed comparative studies, White and colleagues were prepared to announce their findings in 2003. What they said caused quite a sensation among paleoanthropologists, and it was reported in the popular press as well. First, well-controlled radiometric dating (40Ar/39Ar) securely places the remains at between 160,000 and 154,000 ya, making these the best-dated hominin fossils from this time period from anywhere in the world. Note that this date is clearly older than for any other equally modern H. sapiens from anywhere else in the world. Moreover, the preservation and morphology of the remains leave little doubt about their relationship to modern humans. The mostly complete adult cranium is very large, with an extremely long cranial vault. The cranial capacity is 1,450 cm3 , well within the range of contemporary H. sapiens populations. The skull is also in some respects heavily built, with a large, arching browridge in front and a large, projecting occipital protuberance in back. The face does not project, in stark contrast to Eurasian Neandertals. The overall impression is that this individual is clearly Homo sapiens— as are the other fossils from the site.
Following comprehensive statistical studies, Tim White and colleagues concluded that, while not identical to modern people, the Herto fossils are nearmodern. That is, these fossils “sample a population that is on the verge of anatomical modernity but not yet fully modern.” (White et al., 2003, p. 745). To distinguish these individuals from fully modern humans (H. sapiens sapiens), the researchers have placed them in a newly defined subspecies: Homo sapiens idaltu. The word idaltu, from the Afar language, means “elder.”
What can we conclude? First, we can say that these new finds strongly support an African origin of modern humans. The Herto fossils are the right age, and they come from the right place. Besides that, they look much like what we might have predicted. Considering all these facts, they’re the most conclusive fossil evidence yet indicating an African origin of modern humans. What’s more, this fossil evidence is compatible with a great deal of strong genetic data indicating some form of replacement model for human origins.