Kibish Formation Research Articles

An Overview of the Benefit of Archaeology to the Study of African History

Every place around the world has a past. Effort has been made to improve the method of historical studies and research in an effort to better understand the past events, culture, people, places, traditions, values etc. The quest to acquire all these knowledge berried in the distant past is critical to academic excellence not just history as a discipline. Archaeology involves surveying, excavation, and eventually analysis of data collected, to learn more about the past. In broad scope, archaeology relies on cross-disciplinary research. Africa has the longest record of human habitation in the world. The first humans emerged 6-7 million years ago, and among the earliest anatomically modern human skulls found so far were discovered at Omo Kibish, Jebel Irhoud, and Florisbad. However, Africa has the larger part of its past unwritten because of lack of writing knowledge, hence, the critical role of archaeology to supplement oral traditions which modern African historians relied heavily on. This research aim to explicitly detail the benefit of archaeology to the study and understanding of African history, it reveals how archaeology could further aid in debunking Eurocentric views of Africa lacking history and also emphasized the role archaeology could play in helping history students understand the past.

Investigating habitat heterogeneity of Late Pleistocene archaeological sites in eastern Africa from stable isotopes

ABSTRACT Site-specific habitat reconstructions in the form of faunal enamel stable carbon and oxygen isotope data allow for a finer assessment of the context of Homo sapiens in eastern Africa. To date, these studies have focused on a small collection of sites within a constrained spatiotemporal scope. Here, I analyse a compilation of faunal stable isotopes from the Kibish Formation and Porc Epic Cave, Ethiopia, and Rusinga and Mfangano Islands, Karungu, Lukenya Hill, and Panga ya Saidi, Kenya. New data for primate and notably Homo sapiens at Porc Epic are presented. Faunal isotope data indicate that the Lake Victoria and northern Lake Turkana basins were dominated by open grasslands between ~ 105 ka and 50 ka. Sites near the Ethiopian Rift and closer to the coast were at least in part buffered from the environmental changes that occurred further inland. In the following period, ~ 49 ka – 20 ka, inland sites see more wooded conditions while Panga ya Saidi at the coast becomes drier. This compilation provides evidence for spatial and temporal trends in local habitats necessary for understanding the mechanisms through which human populations exchanged genes, ideas, and behaviours during the Late Pleistocene.

Using multiple chronometers to establish a long, directly-dated lacustrine record: Constraining >600,000 years of environmental change at Chew Bahir, Ethiopia

Despite eastern Africa being a key location in the emergence of Homo sapiens and their subsequent dispersal out of Africa, there is a paucity of long, well-dated climate records in the region to contextualize this history. To address this issue, we dated a ∼293 m long composite sediment core from Chew Bahir, south Ethiopia, using three independent chronometers (radiocarbon, 40Ar/39Ar, and optically stimulated luminescence) combined with geochemical correlation to a known-age tephra. The site is located in a climatically sensitive region, and is close to Omo Kibish, the earliest documented Homo sapiens fossil site in eastern Africa, and to the proposed dispersal routes for H. sapiens out of Africa. The 30 ages generated by the various techniques are internally consistent, stratigraphically coherent, and span the full range of the core depth. A Bayesian age-depth model developed using these ages results in a chronology that forms one of the longest independently dated, high-resolution lacustrine sediment records from eastern Africa. The chronology illustrates that any record of environmental change preserved in the composite sediment core from Chew Bahir would span the entire timescale of modern human evolution and dispersal, encompassing the time period of the transition from Acheulean to Middle Stone Age (MSA), and subsequently to Later Stone Age (LSA) technology, making the core well-placed to address questions regarding environmental change and hominin evolutionary adaptation. The benefits to such studies of direct dating and the use of multiple independent chronometers are discussed.

Late Middle Pleistocene Elephants from Natodomeri, Kenya and the Disappearance of Elephas (Proboscidea, Mammalia) in Africa

Comparative morphometric study of recently recovered fossil elephant molars from Natodomeri, Kenya identifies them as belonging to Elephas jolensis and confirms the presence of this species in Members I and II of the Kibish Formation. Improved datation of these geological units constrains them between 205 and 130 ka. Elephas jolensis is also reported from localities in northern, northwestern, eastern, and southern Africa. Thus, including its Natodomeri occurrence, E. jolensis appears to have been pan-African in distribution. Despite the wide geographic distribution of the species, molars of E. jolensis are remarkably uniform morphometrically. They are characterized by their extreme hypsodonty, high amplitude of enamel folding, high lamellar frequency, and plates that are anteroposteriorly thick relative to transverse valley interval spacing. In addition, they exhibit only a modest number of plates (<20 in M3/m3). Elephas jolensis either evolved from or represents the last stage of Elephas recki, the dominant elephant species in East Africa during the late Pliocene-Pleistocene. The dental morphology and isotopic composition of E. jolensis indicates that, like E. recki, it was a dedicated grazer. In the Kibish Formation, E. jolensis is succeeded by Loxodonta africana at 130 ka, coincident with an intensely cool, dry interval marked by episodes of extreme drought. This marked the extirpation of Elephas on the continent. The intensity and increased rate of climate fluctuation may have played an important role in the demise of the specialist, grazing E. recki-E. jolensis lineage in favor of a generalist, mixed feeder such as L. africana.

Gigantic lion, Panthera leo, from the Pleistocene of Natodomeri, eastern Africa

AbstractThe partial skull of a lion from Natodomeri, northwest Kenya is described. The Natodomeri sites are correlated with Member I of the Kibish Formation, dated to between 195 ka and ca. 205 ka. The skull is remarkable for its very great size, equivalent to the largest cave lions (Panthera spelaea [Goldfuss, 1810]) of Pleistocene Eurasia and much larger than any previously known lion from Africa, living or fossil. We hypothesize that this individual represents a previously unknown population or subspecies of lion present in the late Middle and Late Pleistocene of eastern Africa rather than being an indication of climate-driven size increase in lions of that time. This raises questions regarding the extent of our understanding of the pattern and causes of lion evolution in the Late Pleistocene.

The origin and evolution of Homo sapiens.

If we restrict the use of Homo sapiens in the fossil record to specimens which share a significant number of derived features in the skeleton with extant H. sapiens, the origin of our species would be placed in the African late middle Pleistocene, based on fossils such as Omo Kibish 1, Herto 1 and 2, and the Levantine material from Skhul and Qafzeh. However, genetic data suggest that we and our sister species Homo neanderthalensis shared a last common ancestor in the middle Pleistocene approximately 400-700 ka, which is at least 200 000 years earlier than the species origin indicated from the fossils already mentioned. Thus, it is likely that the African fossil record will document early members of the sapiens lineage showing only some of the derived features of late members of the lineage. On that basis, I argue that human fossils such as those from Jebel Irhoud, Florisbad, Eliye Springs and Omo Kibish 2 do represent early members of the species, but variation across the African later middle Pleistocene/early Middle Stone Age fossils shows that there was not a simple linear progression towards later sapiens morphology, and there was chronological overlap between different 'archaic' and 'modern' morphs. Even in the late Pleistocene within and outside Africa, we find H. sapiens specimens which are clearly outside the range of Holocene members of the species, showing the complexity of recent human evolution. The impact on species recognition of late Pleistocene gene flow between the lineages of modern humans, Neanderthals and Denisovans is also discussed, and finally, I reconsider the nature of the middle Pleistocene ancestor of these lineages, based on recent morphological and genetic data.This article is part of the themed issue 'Major transitions in human evolution'.

Paleoenvironmental change in the late Middle Pleistocene–Holocene Kibish Formation, southern Ethiopia: Evidence from ungulate isotopic ecology

East Africa has produced the earliest record of Homo sapiens~200ka and a punctuated record of Middle Stone Age and Later Stone Age behaviors. We lack, however, a detailed late Quaternary paleoenvironmental record for the region, particularly during humid periods. Without a regional record, hypotheses about the evolution and ecology of early Homo sapiens in East Africa remain vague and untestable. The Kibish Formation of southern Ethiopia presents a long, albeit punctuated, record of late Middle Pleistocene to Holocene faunal change in East Africa, which was deposited during humid periods. Here, we present oxygen and carbon stable isotope data of the Kibish ungulates and test whether there are environmental changes within the Kibish Formation. Significant differences in δ18O enamel isotopes are consistent with more humid conditions during the Holocene-age Member IV (~13–4ka) than either Pleistocene-age Member I (~196ka) or Member III (~104ka). Mesowear data document a shift toward more attritional wear among grazers in Member IV and are correlated with more depleted δ18O enamel values, suggesting that the wear pattern shift is linked to the onset of more humid conditions during the Holocene. δ13C enamel values show subtle variations through time, but do not suggest any major changes in diets. We propose that the paleoenvironmental differences evident in Member IV, based on δ18O enamel values, mesowear, and bovid abundances, may be explained by cooler and wetter conditions at the beginning of the Holocene in the lower Omo Valley. The evidence suggesting that the Holocene humid phase is more pronounced than earlier humid phases may explain why arid-adapted grassland ungulates became extinct in East Africa by the Pleistocene–Holocene transition, but persisted through previous humid phases of the late Quaternary.

Taxonomy and paleoecology of fossil Bovidae (Mammalia, Artiodactyla) from the Kibish Formation, southern Ethiopia: Implications for dietary change, biogeography, and the structure of the living bovid faunas of East Africa

The Kibish Formation of southern Ethiopia has yielded the earliest fossils of Homo sapiens, ca. 196ka, and has thus figured prominently in discussions of the origins of modern humans. Here we describe the fossil Bovidae from the Kibish Formation, a record that spans the late Middle Pleistocene to the early to mid-Holocene, and reconstruct aspects of their dietary ecology using mesowear analyses. All of the Kibish bovids represent extant taxa with the exception of the extinct blesbok-like alcelaphin Damaliscus hypsodon; extinct arid-adapted forms Syncerus antiquus and Megalotragus, common in other Late Quaternary sites, are notably absent. Mesowear of the Kibish bovids suggests that the Late Quaternary specimens were characterized by diets with considerably more abrasion-dominated wear relative to their extant conspecifics. Finally, the Kibish record provides supporting evidence for recent phylogeographic hypotheses by demonstrating significant range expansions of Aepyceros melampus, Connochaetes taurinus, Hippotragus equinus, and, to a lesser extent, Kobus kob in the late Middle Pleistocene through the early to mid-Holocene coincident with humid phases that punctuated dry spells of the Late Quaternary.

The Khormusan: Evidence for an MSA East African industry in Nubia

There is clear evidence of lithic technological variability in Middle Paleolithic (MP) assemblages along the Nile valley and in adjacent desert areas. One of the identified variants is the Khormusan, the type-site of which, Site 1017, is located north of the Nile's Second Cataract. The industry has two distinctive characteristics that set it apart from other MP industries within its vicinity. One is the use of a wide variety of raw materials; the second is an apparent correlation between raw material and technology used, suggesting a cultural aspect to raw material management. Stratigraphically, site 1017 is situated within the Dibeira-Jer formation which represents an aggradation stage of the Nile and contains sediments originating from the Ethiopian Highlands. While it has previously been suggested that the site dates to sometime before 42.5 ka, the Dibeira-Jer formation can plausibly be correlated with Nile alluvial sediments in northern Sudan recently dated to 83 ± 24 ka (MIS 5a). This stage coincides with the 81 ka age of sapropel S3, indicating higher Nile flow and stronger monsoon rainfall at these times.Other sites which reflect similar raw material variability and technological traditions are the BNS and KHS sites in the Omo Kibish Formation (Ethiopia) dated to ∼100 ka and ∼190 ka respectively. Based on a lithic comparative study conducted, it is suggested that site 1017 can be seen as representing behavioral patterns which are indicative of East African Middle Stone Age (MSA) technology, adding support to the hypothesis that the Nile Valley was an important dispersal route used by modern humans prior to the long cooling and dry trend beginning with the onset of MIS 4. Techo-typological comparison of the assemblages from the Khormusan sites with other Middle Paleolithic sites from Nubia and East Africa is used to assess the possibility of tracing the dispersal of technological traits across the landscape and through time.

Confirmation of a late middle Pleistocene age for the Omo Kibish 1 cranium by direct uranium-series dating

While it is generally accepted that modern humans evolved in Africa, the specific physical evidence for that origin remains disputed. The modern-looking Omo 1 skeleton, discovered in the Kibish region of Ethiopia in 1967, was controversially dated at ∼130 ka (thousands of years ago) by U-series dating on associated Mollusca, and it was not until 2005 that Ar–Ar dating on associated feldspar crystals in pumice clasts provided evidence for an even older age of ∼195 ka. However, questions continue to be raised about the age and stratigraphic position of this crucial fossil specimen. Here we present direct U-series determinations on the Omo 1 cranium. In spite of significant methodological complications, which are discussed in detail, the results indicate that the human remains do not belong to a later intrusive burial and are the earliest representative of anatomically modern humans. Given the more archaic morphology shown by the apparently contemporaneous Omo 2 calvaria, we suggest that direct U-series dating is applied to this fossil as well, to confirm its age in relation to Omo 1.

Correlation of the KHS Tuff of the Kibish Formation to volcanic ash layers at other sites, and the age of early Homo sapiens (Omo I and Omo II)

Hominin specimens Omo I and Omo II from Member I of the Kibish Formation, Ethiopia are attributed to early Homo sapiens, and an age near 196 ka has been suggested for them. The KHS Tuff, within Member II of the Kibish Formation has not been directly dated at the site, but it is believed to have been deposited at or near the time of formation of sapropel S6 in the Mediterranean Sea. Electron microprobe analyses suggest that the KHS Tuff correlates with the WAVT (Waidedo Vitric Tuff) at Herto, Gona, and Konso (sample TA-55), and with Unit D at Kulkuletti in the Ethiopian Rift Valley. Konso sample TA-55 is older than 154 ka, and Unit D at Kulkuletti is dated at 183 ka. These correlations and ages provide strong support for the age originally suggested for the hominin remains Omo I and Omo II, and for correlation of times of deposition in the Kibish region with formation of sapropels in the Mediterranean Sea. The Aliyo Tuff in Member III of the Kibish Formation is dated at 104 ka, and correlates with Gademotta Unit 15 in the Ethiopian Rift Valley.

Geochronology of the Turkana Depression of Northern Kenya and Southern Ethiopia

Mesozoic and Cenozoic sedimentary rocks in the Turkana Depression of northern Kenya and southern Ethiopia rest on basement rocks that yield K/Ar cooling ages between 433 and 522 Ma. Proven Cretaceous strata are exposed in Lokitaung Gorge in northwest Kenya. Eocene basalts and rhyolites in Lokitaung Gorge, the Nabwal Hills, and at Kangamajoj, date between 34 and 36 Ma, recording the earliest volcanism in the region. Oligocene volcanic rocks, with associated fossiliferous sedimentary strata at Eragaleit, Nakwai, and Lokone, all west of Lake Turkana, are 23 to 28 Ma old, as is the Langaria Formation east of Lake Turkana. Lower and Middle Miocene volcanic and sedimentary sequences are present both east and west of Lake Turkana, where ages from 17.9 to 9.1 Ma have been measured at many levels. Upper Miocene strata are presently known only at Lothagam, with ages ranging from 7.4 to 6.5 Ma. Deposition of Pliocene strata of the Omo Group begins in the Omo-Turkana, Kerio, and South Turkana basins -4.3 Ma ago and continues in parts of those basins until nearly the present time, but with some gaps. These strata are linked through volcanic ash correlations at many levels, as are Pleistocene strata of the Omo Group (principally the Shungura, Koobi Fora, and Nachukui formations). (40) Ar/(39) Ar dates on many volcanic ash layers within the Omo Group, supplemented by K/Ar ages on intercalated basalts and paleomagnetic polarity stratigraphy, provide excellent age control from 4.2 to 0.75 Ma, although there is a gap in the record between -1 Ma and 0.8 Ma. Members I to III of the Kibish Formation in the lower Omo Valley record deposition between 0.2 and 0.1 Ma ago; Member IV, correlative with the Galana Boi Formation, was deposited principally between 12 and 7 ka BP.

Behavioral Modernity—Not Again

“Behavioral modernity” has been a focal point for research in Paleolithic archaeology for decades, but there is now a consensus that it needs to be replaced by a research objective with a better theoretical and methodological grounding. My paper (Shea 2011a) proposed that rather than assuming linkages among the phenomena comprising behavioral modernity, we should instead investigate the sources of variability in particular behaviors by using strategic modeling and principles of behavioral ecology. Porr argues that this proposal is problematical because behavioral ecology is inadequate to explain variability in symbolic/cultural behavior. The evidence Porr cites in support of his argument is that I was unable “to properly explain ‘symbolic behavior’” in the lithic evidence from Omo Kibish. First, I do not agree that the lithic evidence in question, a seeming preference for knapping red rocks and transport of unknappable stone for some modest distance, is necessarily symbolic, and the paper posed alternative hypotheses about this evidence. My reason for mentioning it at all was to show how in the absence of a robust body of middle-range theory for identifying symbolic behavior, Paleolithic archaeologists can find evidence for it wherever they choose to look. Second, use-worn mineral pigments and artifact style variation occur in so many and such varied Pleistocene Old World contexts that a capacity for social use of symbolic artifacts either was clearly evolutionarily primitive or evolved convergently among multiple hominin species dating to at least Middle Pleistocene times. To me, finding some plausibly symbolic dimension of lithic variation among the Omo Kibish assemblages would really be noteworthy only if there were principled reasons for expecting such evidence to be absent from contexts associated with Homo sapiens (Shea 2011b). If anything, Porr’s remarks show the need to examine symbolic/cultural behavior from the standpoints of strategic modeling and behavioral ecology. Whether one is hauling shiny rocks across the landscape, burying or burning one’s dead, or painting the walls of caves, these activities come at variable costs in time and energy. As such, they have variable evolutionary fitness consequences for the people who engage in them. Behavioral ecological principles will probably not shed much light on choices between symbolic behaviors of roughly equivalent cost (e.g., painting reindeer vs. horses), but it cer-

Intrasite spatial variation of the Omo Kibish Middle Stone Age assemblages: Artifact refitting and distribution patterns

The middle–late Pleistocene Kibish Formation of the Lower Omo Valley (Ethiopia) contains some of the oldest dated Homo sapiens fossils. Archaeological excavations at the Omo Kibish between 2002 and 2003 recovered numerous stone tools from extensive horizontal exposures of two sites, KHS (dated to 195 ± 5 kyr) and BNS (dated to at least 104 ± 7 kyr). Analysis of artifact distributions, lithic-debris densities, and refitting artifact sets sheds light on site-formation processes. Both localities reveal weak patterns of differentiation, and BNS seems to have a preferred refit orientation.

Further new hominin fossils from the Kibish Formation, southwestern Ethiopia

In addition to the new fragments of the Omo I skeleton, renewed fieldwork in the Kibish Formation along the lower reaches of the Omo River in southwestern Ethiopia has yielded new hominin finds from the Kibish Formation. The new finds include four heavily mineralized specimens: a partial left tibia and a fragment of a distal fibular diaphysis from Awoke's Hominid Site (AHS), a parietal fragment, and a portion of a juvenile occipital bone. The AHS tibia and fibula derive from Member I and are contemporaneous with Omo I and II. The other specimens derive from Chad's Hominid Site (CHS), and derive from either Member III or IV, which constrains their age between ∼8.6 and ∼104 ka.

Quaternary fossil fish from the Kibish Formation, Omo Valley, Ethiopia

The late Quaternary Kibish Formation of the Omo Valley, southwestern Ethiopia, preserves environments reflecting a history of fluctuations in the level of nearby Lake Turkana over the past 200,000 years. The Kibish Formation has yielded a diverse mammalian fauna (as well as birds and crocodiles), stone tools, and the oldest anatomically modern Homo sapiens. Fish, the most common vertebrate fossils in this unit, are reported in this study. Catfish (especially clariids and Synodontis) and Nile perch ( Lates niloticus) predominate, but the gymnarchid Gymnarchus, a cyprinid ( Barbus), tigerfish ( Hydrocynus), pufferfish ( Tetraodon), and other catfish are also present. In total, nine teleost genera are found in the Kibish Formation, representing a subset of the 37 genera that constitute the modern Omo-Turkana ichthyofauna. Several taxa present in the modern fauna, including Polypterus and members of the family Cichlidae, are not found in the Kibish deposits. Most specimens are preserved as disarticulated or broken skeletal elements, but some preservation of articulated elements (e.g., sets of vertebrae, crania with lower jaws or cleithra) also occurs. Many of the catfish and Nile perch specimens are larger than the largest reported from the modern river or lake. Faunas of Kibish Members I and III closely resemble one another; the fauna from Member IV contains only the three most common taxa ( Clarias, Synodontis, Lates), though this may result from insufficient sampling. Barbed bone points have been collected from the upper part of the formation, indicating a long association between the human inhabitants and the fish fauna of the Omo Valley.

The large-mammal fauna from the Kibish Formation

The Kibish faunal remains are useful for reconstructing the habitat of the earliest documented Homo sapiens and for understanding the community within which early modern humans existed. A diverse assemblage of large mammals, including many species of bovids, suids, and equids, has been recovered from the Kibish Formation. There are no extinct large mammals represented in the fossil assemblage, and the overall taxonomic composition of the fossil fauna is similar to the modern-day wildlife community living near the Omo River. The fossil faunal assemblage shows a paucity of arboreal primates, and carnivore species are rare. However, the faunal sample includes possible Cephalophus (duiker) remains and Hylochoerus meinertzhageni (giant forest hog), taxa that are extremely rare in the African fossil record, and both indicate more closed habitats. Comparative analyses of the Kibish faunal remains using the ecological-diversity approach document close associations with edaphic grassland and woodland vegetation types. These vegetation forms are similar to current habitats surrounding the Omo River.

Stratigraphy and tephra of the Kibish Formation, southwestern Ethiopia

The Kibish Formation in southwestern Ethiopia, with an aggregate thickness of ~105 m, consists of lacustrine, marginal lacustrine, and deltaic deposits. It is divided into four members numbered I to IV on the basis of erosion surfaces (disconformities) between the strata of each member. It overlies the Mursi and Nkalabong formations, the latter of which is here shown to correlate with the Shungura Formation. Tephra layers in each member allow for secure correlation between geographically separated sections on the basis of the composition of their volcanic glass. Members I, III, and IV of the Kibish Formation appear to have been deposited at the same times as sapropels S7 (197 ka), S4 (104 ka), and S1 (8 ka) in the eastern Mediterranean Sea, respectively. We correlate the KHS Tuff of the Kibish Formation with a >154-kyr-old unnamed tuff in the Konso Formation. Tephra in Member IV may derive from Mount Wenchi, a volcano situated on the divide between the Omo and Blue Nile drainage basins. Thin-bedded sedimentary layers probably represent annual deposition reflecting rapid sedimentation (~30 m/kyr) of parts of the formation. This conclusion is supported by variation in paleomagnetic inclination through a sequence of these layers at KHS. Two fossils of early Homo sapiens (Omo I and Omo II) derive from Member I. Their stratigraphic placement is confirmed by analysis of the KHS Tuff in the lower part of Member II at both fossil sites. The KHS Tuff lies above a disconformity, which itself lies above the fossils at both sites. 40Ar/ 39Ar dates provide an estimated age of ~195 kyr for these fossils. Omo III, a third fossil H. sapiens, probably also derives from Member I of the Kibish Formation and is of similar age. Hominin fossils from AHS, a new site, also derive from Member I. Hominin fossils from CHS can only be placed between 104 ka and 10 ka, the H. sapiens specimen from JHS is most likely 9–13 kyr in age, and a partial skeleton of H. sapiens from Pelvic Corner is most likely ~6.6 kyr in age.

The Middle Stone Age archaeology of the Lower Omo Valley Kibish Formation: Excavations, lithic assemblages, and inferred patterns of early Homo sapiens behavior

This paper describes the excavation, stratigraphy, and lithic assemblages of Middle Stone Age sites from the Omo Kibish Formation (Lower Omo Valley, southwestern Ethiopia). Three sites were excavated, two in Kibish Member I (KHS and AHS) and one at the base of Member III (BNS). The assemblages are dominated by relatively high-quality raw materials procured as pebbles from local gravels. The principal modes of core preparation are radial/centripetal Levallois and discoidal. Retouched tools are rare. Foliate bifaces are present, as are larger tools, such as handaxes, picks, and lanceolates, but these are more common among surface finds than among excavated assemblages. Middle Stone Age assemblages shed light on the adaptations of the earliest-known Homo sapiens populations in Africa.

A description of the Omo I postcranial skeleton, including newly discovered fossils

Recent fieldwork in the Kibish Formation has expanded our knowledge of the geological, archaeological, and faunal context of the Omo I skeleton, the earliest known anatomically modern human. In the course of this fieldwork, several additional fragments of the skeleton were recovered: a middle manual phalanx, a distal manual phalanx, a right talus, a large and a small fragment of the left os coxae, a portion of the distal diaphysis of the right femur that conjoins with the distal epiphysis recovered in 1967, and a costal fragment. Some researchers have described the original postcranial fragments of Omo I as anatomically modern but have noted that a variety of aspects of the specimen's morphology depart from the usual anatomy of many recent populations. Reanalysis confirms this conclusion. Some of the unusual features in Omo I—a medially facing radial tuberosity, a laterally flaring facet on the talus for the lateral malleolus, and reduced dorsovolar curvature of the base of metacarpal I—are shared with Neandertals, some early modern humans from Skhul and Qafzeh, and some individuals from the European Gravettian, raising the possibility that Eurasian early modern humans inherited these features from an African predecessor rather than Neandertals. The fragment of the os coxae does not unambiguously diagnose Omo I's sex: the greater sciatic notch is intermediate in form, the acetabulum is large (male?), and a preauricular sulcus is present (female?). The preserved portion of the left humerus suggests that Omo I was quite tall, perhaps 178–182 cm, but the first metatarsal suggests a shorter stature of 162–173 cm. The morphology of the auricular surface of the os coxae suggests a young adult age.