Omo remains
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The Omo remains are a collection of
hominin The Hominini form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes the extant genera ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos) and in standard usage excludes the genus ''Gorilla'' (gorillas). The t ...
This article quotes historic texts that use the terms 'hominid' and 'hominin' with meanings that may be different from their modern usages. This is because several revisions in classifying the great apes have caused the use of the term "hominid" to vary over time. Its original meaning referred only to humans (''
Homo ''Homo'' () is the genus that emerged in the (otherwise extinct) genus ''Australopithecus'' that encompasses the extant species ''Homo sapiens'' ( modern humans), plus several extinct species classified as either ancestral to or closely relate ...
'') and their closest relatives. That restrictive usage has been largely assumed by the term "
hominin The Hominini form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes the extant genera ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos) and in standard usage excludes the genus ''Gorilla'' (gorillas). The t ...
", which comprises all members of the human
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
after the split from the chimpanzees ('' Pan''). The modern meaning of the term "hominid" refers to all the great apes, including humans. Usage still varies, however, and some scientists and laypersons still use the term in the original restrictive sense; the scholarly literature generally will show the traditional usage until around the end of the 20th century. For further information, see ''
Hominini The Hominini form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes the extant genera ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos) and in standard usage excludes the genus ''Gorilla'' (gorillas). The t ...
'' (at "hominins") and ''
Hominidae The Hominidae (), whose members are known as the great apes or hominids (), are a taxonomic family of primates that includes eight extant species in four genera: '' Pongo'' (the Bornean, Sumatran and Tapanuli orangutan); ''Gorilla'' (the ea ...
'' (at discussion of the terms "hominid" and "hominin" in the lede section).
In this article, ''hominid'' is italicized when the traditional term is necessary to keep as-is—as in a quotation, or a record, or a title, etc.
bones discovered between 1967 and 1974 at the
Omo Kibish The Omo Kibish Formation or simply Kibish Formation is a geological formation in the Lower Omo Valley of southwestern Ethiopia. It is named after the nearby Omo River (Ethiopia), Omo River and is subdivided into four members known as Members I-IV. ...
sites near the
Omo River The Omo River (also called Omo-Bottego) in southern Ethiopia is the largest Ethiopian river outside the Nile, Nile Basin. Its course is entirely contained within the boundaries of Ethiopia, and it empties into Lake Turkana on the border with Keny ...
, in
Omo National Park Omo National Park is a national park in Ethiopia founded in 1980. Located in the Southern Nations, Nationalities, and Peoples' Region on the west bank of the Omo River, the park covers approximately 4,068 square kilometers, about 870 kilometers so ...
in south-western
Ethiopia Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the ...
. etrieved 2011-08-27/ref> The bones were recovered by a scientific team from the Kenya National Museums directed by
Richard Leakey Richard Erskine Frere Leakey (19 December 1944 – 2 January 2022) was a Kenyan paleoanthropologist, conservationist and politician. Leakey held a number of official positions in Kenya, mostly in institutions of archaeology and wildlife cons ...
and others. The remains from Kamoya's ''Hominid'' Site (KHS) were called ''Omo I'' and those from Paul I. Abell's ''Hominid'' Site (PHS) were called ''Omo II''.


Fossils

The bones found include two partial skulls, four jaws, a legbone, approximately two hundred teeth, and several other fossilized parts. Both of the specimens, Omo I and Omo II, are classified as anatomically modern humans (''
Homo sapiens Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
''), but they differ from each other in morphological traits. The Omo I
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
s indicate more modern traits, while studies of the
postcranial Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated s ...
remains of Omo II indicate an overall modern human morphology with some primitive features. The fossils were found in a layer of
tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock cont ...
, between a lower, older geologic layer named Member I and a higher, newer layer dubbed Member III. The Omo I and Omo II hominin fossils were taken from similar stratigraphic levels above Member I. Because of the very limited fauna and the few stone artifacts that were found at the sites when the original Omo remains were discovered, the provenance and estimated age of the Kibish ''hominids'' are uncertain. In 2008, new bone remains were discovered from Awoke's ''Hominid'' Site (AHS). The AHS fossil's
tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...
and
fibula The fibula or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. Its upper extremity is ...
were unearthed from Member I, the same layer from which the other Omo remains derive.


Dating and implications

About 30 years after the original finds, a detailed stratigraphic analysis of the area surrounding the fossils was conducted. The Member I layer was argon-dated to 195,000 years ago, and the (higher layer) Member III was dated to 105,000 years ago. Numerous recent lithic records verify the tool technology from Members I and III to the
Middle Stone Age The Middle Stone Age (or MSA) was a period of African prehistory between the Early Stone Age and the Late Stone Age. It is generally considered to have begun around 280,000 years ago and ended around 50–25,000 years ago. The beginnings of pa ...
. The lower layer, Member I, (below the fossils) is considerably older than the 160,000-year-old Herto remains designated as ''
Homo sapiens idaltu Herto Man refers to the 154,000 - 160,000-year-old human remains (''Homo sapiens'') discovered in 1997 from the Upper Herto member of the Bouri Formation in the Afar Triangle, Ethiopia. The discovery of Herto Man was especially significant at the ...
''. The rainy conditions at that time—which are known from isotopic ages on the Kibish Formation corresponding to the ages of Mediterranean
sapropel Sapropel (a contraction of ancient Greek words ''sapros'' and ''pelos'', meaning putrefaction and mud (or clay), respectively) is a term used in marine geology to describe dark-coloured sediments that are rich in organic matter. Organic carbon con ...
s—suggest increased flow of the Nile River and, therefore, increased flow of the Omo River. But the climates changed such that, after 185,000 years ago conditions were so dry as to not allow
speleothems A speleothem (; ) is a geological formation by mineral deposition (geology), deposits that accumulate over time in natural caves. Speleothems most commonly form in calcareous caves due to carbonate dissolution reactions. They can take a variety ...
to grow in the caverns in the
Levant The Levant () is an approximate historical geographical term referring to a large area in the Eastern Mediterranean region of Western Asia. In its narrowest sense, which is in use today in archaeology and other cultural contexts, it is eq ...
ine land-bridge region, the vital inroad for migration to Eurasia. Parts of the fossils are the earliest to have been classified by Leakey as ''
Homo sapiens Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
''. In 2004, the geological layers around the fossils were dated, with the age of the "Kibish hominids" estimated at housand years ago For some time, these were the oldest known fossils classified as ''H. sapiens'' (the
Florisbad Skull The Florisbad Skull is an important human fossil of the early Middle Stone Age, representing either late ''Homo heidelbergensis'' or early ''Homo sapiens''. It was discovered in 1932 by T. F. Dreyer at the Florisbad archaeological and paleontolo ...
is older, but its classification as ''H. sapiens'' was then disputed). With the dating of the Jebel Irhoud 1–5 to before 250 ka (315 ± 34 ka, and ) in 2017, as well as the classification of the Florisbad Skull as ''H. sapiens'', this is no longer the case. In 2022, a study by Vidal et al. found an earlier age for the Omo fossils than previously reported, revising the date assigned to them as, a minimum date of approximately 233,000 years old.


See also

*
List of fossil sites This list of fossil sites is a worldwide list of localities known well for the presence of fossils. Some entries in this list are notable for a single, unique find, while others are notable for the large number of fossils found there. Many of t ...
''(with link directory)'' *
List of human fossils The following tables give an overview of notable finds of hominin fossils and remains relating to human evolution, beginning with the formation of the tribe Hominini (the divergence of the human and chimpanzee lineages) in the late Miocene, roug ...
*
Recent African origin of modern humans In paleoanthropology, the recent African origin of modern humans, also called the "Out of Africa" theory (OOA), recent single-origin hypothesis (RSOH), replacement hypothesis, or recent African origin model (RAO), is the dominant model of the ...


Notes


References


External links


Picture of the skulls
{{DEFAULTSORT:Omo Remains Archaeological sites in Ethiopia Recent African origin of modern humans Prehistoric Ethiopia Homo sapiens fossils Archaeological discoveries in Ethiopia Southern Nations, Nationalities, and Peoples' Region Archaeology of Eastern Africa