Early Pleistocene Homo erectus fossils from Konso, southern Ethiopia

Abstract

Homo erectus has been broadly defined to include fossils from Africa, Asia, and possibly Europe, or restricted to a supposedly confined Asian clade. Recently discovered fossils of H. erectus are allowing new insights into aspects of its evolution, such as the timing and mode of the species' emergence in Africa and its relationship to Asian populations. However, the currently available African record predating 1.0 Ma is poor, consisting of the Turkana basin, Olduvai and the more limited South African materials. Here, we describe and compare eight craniodental fossils of ~1.4 Ma recovered from Konso, Ethiopia, that we attribute to H. erectus. These include KGA10-1, one of the better-preserved H. erectus mandibular specimens known from eastern Africa, and other fragmentary dental and cranial remains. The Konso H. erectus fossils show a mosaic of primitive and derived features. These include a large and thick mandibular corpus, a moderately developed lateral prominence, a reduced premolar morphology, and a tendency for smaller relative sizes of the posterior molars compared with earlier Homo. In some dentognathic details, such as the lack of a buccolingually narrow M1 and the presence of double mental foramina, the Konso fossils differ from eastern African H. erectus of ≥1.5 Ma. The fragmentary cranial remains exhibit weak angular and occipital tori, and an apparently weak occipital flexion, as with the eastern African H. erectus examples known from ~1.65 to 1.2 Ma. The available evidence is consistent with the interpretation that African early H. erectus shows morphological continuity within the ~1.65 to 1.0 Ma time period, with relatively little morphological evolution prior to 1.4 Ma and advanced dentognathic gracility occurring sometime thereafter. The Konso evidence corroborates the hypothesis that the African H. erectus populations represent a variable but continuous evolutionary succession that was a likely source of multiple events of gene flow to the Eurasian continent.

The origins of the Acheulean: past and present perspectives on a major transition in human evolution

“…This association works relatively well for 1.6-1.3 Myr Acheulean assemblages in Konso [106] and, possibly, Olduvai Gorgeas no Homo habilis remains are reported from Middle Bed II (i.e. when handaxes begin to appear in the Olduvai record), and the OH9 erectus calvaria is attributed to Upper Bed II.…”

“…In Sterkfontein Member 5, contextual association between the Early Acheulean and the human remains attributed to H. erectus is unclear [72]. While the early age of H. erectus remains in East Turkana-1.9 Myr for KNM-ER 1813 (but see [106]) and ca 1.63 Myr for KNM-ER 3733 [107]-is often cited to highlight the co-emergence of a new technology alongside a new human species, Koobi Fora is precisely the area where no clear evidence of earliest Acheulean exists.…”

Descriptions of the dental remains of <i>Homo floresiensis</i>

“…However, tooth rotation is a relatively commonly observed dental anomaly both in modern (Jacob et al, 2006;Lukacs et al, 2006) and pre-modern (e.g. Early Pleistocene Homo from Dmanisi (Rightmire et al, 2006) and Konso (Suwa et al, 2007)) hominins as well as other mammals (Natsume et al, 2006), with suggested etiologies including some genetic mechanism and a lack of space for the normal tooth eruption (Baccetti, 1998;Natsume et al, 2006). Therefore this trait is not taxonomically diagnostic and does not necessarily indicate a severe growth abnormality.…”

The characteristics and chronology of the earliest Acheulean at Konso, Ethiopia

“…Field research and laboratory analysis thereafter established that the formation spans the time period >1.9 to ∼0.8 Ma (20)(21)(22). Abundant lithic assemblages and vertebrate fossils have been recovered (23)(24)(25), including fossil remains of Australopithecus boisei (∼1.43 Ma) and H. erectus (∼1.45 to ∼1.25 Ma) (19,26,27).…”