The Omo remains are a collection of hominid bones discovered between 1967 and 1974 at the Kibish sites near the Omo River, Omo National Park in south-western Ethiopia. [1] The bones were recovered by a scientific team from the Kenya National Museums directed by Richard Leakey and others.[2] The remains from the Kamoya's Hominid Site (KHS) were called Omo 1 and those from Paul's Hominid Site (PHS) Omo 2. Parts of the fossils are the earliest classified by Richard Leakey as Homo sapiens. The results of Ar40-Ar39 dating of the geologic tuffs in 2004 were [3] for the layer below the fossil tuff (Member I - 198 ± 14 ka) and the layer over the fossil tuff (Member III - 104 ± 7 ka).[3] In a 2005 "Nature News" article on the fossils, Nature magazine called Ethiopia the current choice for the "cradle of Homo sapiens".[4] The two specimens Omo 1 and Omo 2 differ in morphological traits. Omo 2 characteristics indicate more archaic traits. Studies of the postcranial remains of Omo I indicate an overall modern human morphology with a number of primitive features. Authors of the new Homo Omo dating say that the "preferred estimate of the age of the Kibish hominids is 195 ± 5 ka," which is also the record earliest date in this category.[3]
Omo I and Omo II hominid fossils are from similar stratigraphic levels over Member I. [5][3]
The bones includes two partial skulls, four jaws, a legbone, around two hundred teeth and several other parts. [1] Very limited fauna and a few stone artefacts found at the sites led to "the reliability of the dates and the provenance of the Kibish hominids" being "repeatedly questioned." [2]
About 30 years later, a detailed stratigraphic analysis of the area surrounding the fossils was carried out. This analysis argon-dated the Member I layer to 195 kya and that of Member III to 105 kya. The numerous new lithic records from Members I and III verify tool technology to the Middle Stone Age.[2] The lower layer (below the fossils) is considerably older than the 160,000-year-old Herto remains designated Homo sapiens idaltu, thought to have been the earliest humans. This suggests that, if humans did originate in Africa as is the current hypothesis, then they did not extend beyond there until much later than was previously thought. The rainy conditions at that time, which are known from isotopic ages on the Kibish Formation corresponding to ages of Mediterranean sapropels, suggest increased flow of the Nile River and necessarily increased flow of the Omo River. Climatic conditions after 185 ka were too dry to allow speleothems to grow in the Levantine land-bridge inroad Eurasian migration.[6] RAO theory suggests that H. sapiens sapiens evolved alongside other hominids for a considerable period of time before the other hominids became extinct.
In 2008 new bone remains were discovered from Awoke's Hominid Site (AHS). The AHS fossil's tibia and fibula were unearthed from Member I, the same layer from which the other Omo remains derive.[7]
|
|||||||||||||||||||||||
