title: Confirmation of a late middle Pleistocene age for the Omo Kibish 1 cranium by direct uranium-series dating.
abstract: 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.
authors.affiliation: Research School of Earth Sciences, The Australian National University, Canberra ACT 0200, Australia. maubert@uow.edu.au
authors.forename: Maxime
authors.initials: M
authors.lastname: Aubert
authors.forename: Alistair W G
authors.initials: AW
authors.lastname: Pike
authors.forename: Chris
authors.initials: C
authors.lastname: Stringer
authors.forename: Antonis
authors.initials: A
authors.lastname: Bartsiokas
authors.forename: Les
authors.initials: L
authors.lastname: Kinsley
authors.forename: Stephen
authors.initials: S
authors.lastname: Eggins
authors.forename: Michael
authors.initials: M
authors.lastname: Day
authors.forename: Rainer
authors.initials: R
authors.lastname: Grün
mesh_terms: D000818:Animals; D005002:Ethiopia; D005580:Fossils; D015186:Hominidae / Q000033:anatomy & histology*; D055110:Radiometric Dating / Q000379:methods*; D012886:Skull / Q000033:anatomy & histology*; D014501:Uranium / Q000737:chemistry
chemical_list: D014501:Uranium