Omo 1 and Omo 2

from Wikipedia, the free encyclopedia
Omo 1 (reconstruction; cast in the Musée des Civilizations Noires de Dakar, Senegal)

As Omo 1 and Omo 2 two resulting in fragments are fossils of the genus Homo , respectively. They were recovered from 1967 as part of an excavation initiated by Richard Leakey in the valley of the Omo River in southern Ethiopia and described scientifically for the first time in 1969 by Michael Herbert Day . Parts of the skull and bones below the skull of a young adult were preserved from Omo 1 , while Omo 2 - a surface find - is the largely preserved skull roof of an older adult. Another, poorly preserved partial skull roof - Omo 3 - largely resembles the fossil Omo 1. It is kept in the National Museum of Ethiopia in Addis Ababa .

The finds

The fossils come from two neighboring excavation sites. They were initially dated to an age of around 130,000 years using uranium-thorium dating . At the same time, Richard Leakey identified them as the remains of anatomically modern humans ( Homo sapiens ), whereby Omo 2 was interpreted as " archaic " in comparison with Omo 1 (see archaic Homo sapiens ). The timing of the fossil finds remained controversial for a long time. However, new dating of the find layer (“Member I”) using the 39 Ar- 40 Ar method indicate an older age of 190,000 to 200,000 years. If this dating continues, these fossils would be the second oldest known evidence of Homo sapiens after those of Djebel Irhoud .

It was objected, however, that the skulls - more precisely the anatomical features derived in particular from the elaborate reconstruction of the skulls - do not have enough in common with Homo sapiens , but rather with the chronospecies Homo erectus that preceded Homo sapiens . In 1991, for example, reference was made to a more pronounced anatomical correspondence between Omo 2 and the fossil Arago XXI (" Man of Tautavel "); however, it is not uncommon for there to be a lack of clarity when assigning presumed “ transitional forms ”. Donald Johanson wrote in 2006: "The pieces are anatomically undoubtedly modern, and with their presumably old age they very quickly became decisive pieces of evidence for those who believed that Homo sapiens first developed in Africa and only later colonized the rest of the world" ( Out -of-Africa theory ).

Omo 1

The numerous fragments of the skull of Omo 1 come mainly from the rear and the right side of the skull. Fragments of the forehead, the facial skull and the lower jaw from Omo 1 have also survived, but they are mostly separated from each other due to missing intermediate pieces. From the skeleton below the head, parts of the shoulder girdle , several well-preserved vertebrae , fragments of the ribs and pelvis and some bones of the arms and legs have been preserved.

The reconstruction of the contents of the skull of Omo 1 suggests a brain volume of 1435 cm 3 . The long, arched parietal bones of the skull and the short, broad face with a high forehead are clearly modern . The upper jaw has a modern, U-shaped palate, the lower jaw has a chin , and two preserved teeth are similar in shape and size to those of Homo sapiens .

Omo 2

Omo 2 is a strongly fragmented, but largely preserved skullcap ( calvaria ), the lateral parts of which are missing. The reconstruction of the skull's contents also suggests a brain volume of over 1400 cm 3 . “The Calvaria Omo 2, which in some details Kabwe 1 z. T. strikingly similar, is classified as late archaic H. sapiens ; On the other hand, however, it should also have characteristic features typical of anatomically modern humans, e.g. B. the separation of the eyebrow arches ( Arcus superciliares ) and the supraorbital triangle ( Trigonum supraorbitale ) , which is typical for H. sapiens . ”In 2008, Donald Johanson pointed out that Omo 2 was much stronger than Omo 1 and had different muscle attachments as well as an angled occiput (occipital ridge ), and the forehead is receding. However, Omo also has 2 long arched parietal bones and the top of the skull is wider than at the base. So he considered that they weren't both from the same population.

Web links

  • sciencedaily.com of February 23, 2005: The Oldest Homo Sapiens: Fossils Push Human Emergence Back To 195,000 Years Ago. (with illustration of the bones of Omo 1)

Individual evidence

  1. ↑ Michael Herbert Day : Early Homo sapiens Remains from the Omo River Region of South-west Ethiopia: Omo Human Skeletal Remains. In: Nature . Volume 222, 1969, pp. 1135-1138, doi : 10.1038 / 2221135a0
  2. ↑ K. W. Butzer, F. H. Brown, D. L. Thurber: Horizontal sediments of the Lower Omo Valley: the Kibish Formation. In: Quaternaria. Volume 11, 1969, pp. 15-29
  3. ^ REF Leakey : Early Homo sapiens Remains from the Omo River Region of South-west Ethiopia: Faunal Remains from the Omo Valley. In: Nature. Volume 222, 1969, pp. 1132-1133, doi : 10.1038 / 2221132a0
  4. ↑ John G. Fleagle , Zelalem Assefa, Francis H. Brown, and John J. Shea : Paleoanthropology of the Kibish Formation, southern Ethiopia: Introduction. In: Journal of Human Evolution. Volume 55, No. 3, 2008, pp. 360-365, doi : 10.1016 / j.jhevol.2008.05.007
  5. ↑ Ian McDougall , Francis H. Brown and John G. Fleagle: Stratigraphic placement and age of modern humans from Kibish, Ethiopia. In: Nature. Volume 433, 2005, pp. 733-736, doi : 10.1038 / nature03258
  6. ^ Ian McDougall, Francis H. Brown, and John G. Fleagle: Sapropels and the age of hominins Omo I and II, Kibish, Ethiopia. In: Journal of Human Evolution. Volume 55, No. 3, 2008, pp. 409-420, doi : 10.1016 / j.jhevol.2008.05.012
  7. ↑ Michael Herbert Day and C. Stringer : A reconsideration of the Omo Kibish remains and the erectus-sapiens transition. In: Henry de Lumley (Ed.): 1st Congrès International de Paléontologie Humain (Prétirage). Nice 1982, pp. 814-846
  8. ↑ Michael Herbert Day and Chris Stringer: Les restes crâniens d'Omo-Kibish et leur classification à l'intérieur du genre Homo. In: L'Anthropologie. Volume 95, 1991, pp. 573-594
  9. ↑ a b c d Donald Johanson , Blake Edgar: Lucy and her children. Elsevier, 2nd expanded edition, Munich 2008, p. 252, ISBN 978-3-8274-1670-4
  10. ↑ Winfried Henke , Hartmut Rothe : Stammesgeschichte des Menschen. An introduction. Springer Verlag, Berlin a. a. 1999, p. 268, ISBN 3-540-64831-3