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Shigehiro Katoh

Bio: Shigehiro Katoh is an academic researcher from American Museum of Natural History. The author has contributed to research in topics: Tephra & Holocene. The author has an hindex of 16, co-authored 47 publications receiving 1628 citations.

Papers
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Journal ArticleDOI
12 Jun 2003-Nature
TL;DR: Stratigraphically associated Late Middle Pleistocene artefacts and fossils from fluvial and lake margin sandstones of the Upper Herto Member of the Bouri Formation, Middle Awash, Afar Rift, Ethiopia and archaeological assemblages contain elements of both Acheulean and Middle Stone Age technocomplexes.
Abstract: Clarifying the geographic, environmental and behavioural contexts in which the emergence of anatomically modern Homo sapiens occurred has proved difficult, particularly because Africa lacked adequate geochronological, palaeontological and archaeological evidence. The discovery of anatomically modern Homo sapiens fossils at Herto, Ethiopia, changes this. Here we report on stratigraphically associated Late Middle Pleistocene artefacts and fossils from fluvial and lake margin sandstones of the Upper Herto Member of the Bouri Formation, Middle Awash, Afar Rift, Ethiopia. The fossils and artefacts are dated between 160,000 and 154,000 years ago by precise age determinations using the 40Ar/39Ar method. The archaeological assemblages contain elements of both Acheulean and Middle Stone Age technocomplexes. Associated faunal remains indicate repeated, systematic butchery of hippopotamus carcasses. Contemporary adult and juvenile Homo sapiens fossil crania manifest bone modifications indicative of deliberate mortuary practices.

353 citations

Journal ArticleDOI
TL;DR: A newly established chronometric calibration is provided for the Acheulean assemblages of the Konso Formation, southern Ethiopia, which span the time period ∼1.75 to <1.0 Ma, paralleling the emergence of Homo erectus-like hominid morphology.
Abstract: The Acheulean technological tradition, characterized by a large (>10 cm) flake-based component, represents a significant technological advance over the Oldowan. Although stone tool assemblages attributed to the Acheulean have been reported from as early as circa 1.6–1.75 Ma, the characteristics of these earliest occurrences and comparisons with later assemblages have not been reported in detail. Here, we provide a newly established chronometric calibration for the Acheulean assemblages of the Konso Formation, southern Ethiopia, which span the time period ∼1.75 to <1.0 Ma. The earliest Konso Acheulean is chronologically indistinguishable from the assemblage recently published as the world’s earliest with an age of ∼1.75 Ma at Kokiselei, west of Lake Turkana, Kenya. This Konso assemblage is characterized by a combination of large picks and crude bifaces/unifaces made predominantly on large flake blanks. An increase in the number of flake scars was observed within the Konso Formation handaxe assemblages through time, but this was less so with picks. The Konso evidence suggests that both picks and handaxes were essential components of the Acheulean from its initial stages and that the two probably differed in function. The temporal refinement seen, especially in the handaxe forms at Konso, implies enhanced function through time, perhaps in processing carcasses with long and stable cutting edges. The documentation of the earliest Acheulean at ∼1.75 Ma in both northern Kenya and southern Ethiopia suggests that behavioral novelties were being established in a regional scale at that time, paralleling the emergence of Homo erectus-like hominid morphology.

307 citations

Journal ArticleDOI
23 Aug 2007-Nature
TL;DR: The combined evidence suggests that Chororapithecus may be a basal member of the gorilla clade, and that the latter exhibited some amount of adaptive and phyletic diversity at around 10–11 Myr ago.
Abstract: Timing the divergence between the gorilla, chimp and human lineages has been the province of molecular phylogeny largely unconstrained by fossil evidence. Gen Suwa et al. now present fossil teeth from Ethiopia which look very similar to those of a modern gorilla, even though they are 10 million years old. If the teeth, assigned to a new species of fossil ape, are from a creature on the gorilla lineage, then the divergence between gorillas and the chimp–human stock must have happened before that time, constraining divergence dates reached through the comparison of contemporary genetic sequences. Fossil teeth from Ethiopia are presented that look very similar to those of a modern gorilla, despite being 10 million years old. If the teeth, assigned to a new species of fossil ape, come from a creature on the gorilla lineage, then the divergence between gorillas and the chimp–human stock must have happened before that time, constraining divergence dates reached through the comparison of contemporary genetic sequences. With the discovery of Ardipithecus, Orrorin and Sahelanthropus1,2,3,4,5,6,7, our knowledge of hominid evolution before the emergence of Pliocene species of Australopithecus8,9 has significantly increased, extending the hominid fossil record back to at least 6 million years (Myr) ago. However, because of the dearth of fossil hominoid remains in sub-Saharan Africa spanning the period 12–7 Myr ago, nothing is known of the actual timing and mode of divergence of the African ape and hominid lineages. Most genomic-based studies suggest a late divergence date—5–6 Myr ago and 6–8 Myr ago for the human–chimp and human–gorilla splits, respectively10,11,12,13,14—and some palaeontological and molecular analyses hypothesize a Eurasian origin of the African ape and hominid clade15,16. We report here the discovery and recognition of a new species of great ape, Chororapithecus abyssinicus, from the 10–10.5-Myr-old deposits of the Chorora Formation at the southern margin of the Afar rift. To the best of our knowledge, these are the first fossils of a large-bodied Miocene ape from the African continent north of Kenya. They exhibit a gorilla-sized dentition that combines distinct shearing crests with thick enamel on its ‘functional’ side cusps. Visualization of the enamel–dentine junction by micro-computed tomography reveals shearing crest features that partly resemble the modern gorilla condition. These features represent genetically based structural modifications probably associated with an initial adaptation to a comparatively fibrous diet. The relatively flat cuspal enamel–dentine junction and thick enamel, however, suggest a concurrent adaptation to hard and/or abrasive food items. The combined evidence suggests that Chororapithecus may be a basal member of the gorilla clade, and that the latter exhibited some amount of adaptive and phyletic diversity at around 10–11 Myr ago.

213 citations

Journal ArticleDOI
02 Oct 1997-Nature
TL;DR: The unexpected combination of cranial and facial features of this skull cautions against the excessive taxonomic splitting of early hominids based on morphological detail documented in small and/or geographically restricted samples.
Abstract: Australopithecus boisei was first described from a cranium recovered in 1959 from Olduvai Gorge, Tanzania1,2. This and subsequent finds, mostly from Kenya's Turkana basin3,4,5, resulted in its characterization as a specialized Australopithecus species with a hyper-robust masticatory apparatus2,4,6. A distinct A. boisei facial morphology has been emphasized to differentiate robust Australopithecus lineages from East and South Africa6. A preference for closed and/or wet habitats has been hypothesized7. Here we report some new A. boisei specimens, including the taxon's first cranium and associated mandible, from Konso, Ethiopia. These fossils extend the known geographical range of A. boisei. They provide clear evidence for the coexistence of A. boisei and Homo erectus within a predominantly dry grassland environment. The A. boisei specimens from Konso demonstrate considerable morphological variation within the species. The unexpected combination of cranial and facial features of this skull cautions against the excessive taxonomic splitting of early hominids based on morphological detail documented in small and/or geographically restricted samples.

122 citations

Journal ArticleDOI
TL;DR: A magnetic polarity stratigraphy spanning more than the past 3.2 Myr was determined for a long 1545 m continuous sedimentary sequence of marine, fluvial, and lacustrine deposits from the Osaka Basin, southwestern Japan as discussed by the authors.

78 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the best dated and most complete African mammal fossil databases indicate African faunal assemblage and speciation changes during the Pliocene-Pleistocene interval (the last ca. 5.3 million years) were mediated by changes in African climate or shifts in climate variability.

1,127 citations

Journal ArticleDOI
12 Jun 2003-Nature
TL;DR: Fossilized hominid crania from Herto, Middle Awash, Ethiopia are described and provide crucial evidence on the location, timing and contextual circumstances of the emergence of Homo sapiens.
Abstract: The origin of anatomically modern Homo sapiens and the fate of Neanderthals have been fundamental questions in human evolutionary studies for over a century. A key barrier to the resolution of these questions has been the lack of substantial and accurately dated African hominid fossils from between 100,000 and 300,000 years ago. Here we describe fossilized hominid crania from Herto, Middle Awash, Ethiopia, that fill this gap and provide crucial evidence on the location, timing and contextual circumstances of the emergence of Homo sapiens. Radioisotopically dated to between 160,000 and 154,000 years ago, these new fossils predate classic Neanderthals and lack their derived features. The Herto hominids are morphologically and chronologically intermediate between archaic African fossils and later anatomically modern Late Pleistocene humans. They therefore represent the probable immediate ancestors of anatomically modern humans. Their anatomy and antiquity constitute strong evidence of modern-human emergence in Africa.

871 citations

Journal ArticleDOI
17 Feb 2005-Nature
TL;DR: In this article, it was shown that the Omo I and Omo II hominid fossils are from similar stratigraphic levels in Member I of the Kibish Formation.
Abstract: In 1967 the Kibish Formation in southern Ethiopia yielded hominid cranial remains identified as early anatomically modern humans, assigned to Homo sapiens. However, the provenance and age of the fossils have been much debated. Here we confirm that the Omo I and Omo II hominid fossils are from similar stratigraphic levels in Member I of the Kibish Formation, despite the view that Omo I is more modern in appearance than Omo II. 40Ar/39Ar ages on feldspar crystals from pumice clasts within a tuff in Member I below the hominid levels place an older limit of 198 +/- 14 kyr (weighted mean age 196 +/- 2 kyr) on the hominids. A younger age limit of 104 +/- 7 kyr is provided by feldspars from pumice clasts in a Member III tuff. Geological evidence indicates rapid deposition of each member of the Kibish Formation. Isotopic ages on the Kibish Formation correspond to ages of Mediterranean sapropels, which reflect increased flow of the Nile River, and necessarily increased flow of the Omo River. Thus the 40Ar/39Ar age measurements, together with the sapropel correlations, indicate that the hominid fossils have an age close to the older limit. Our preferred estimate of the age of the Kibish hominids is 195 +/- 5 kyr, making them the earliest well-dated anatomically modern humans yet described.

805 citations

Journal ArticleDOI
TL;DR: The role of osteogenic factors in the adaptive response and interactive function of OB and EC during the multi-step process of bone repair will be discussed.

728 citations

Journal ArticleDOI
TL;DR: A modest effect of purifying selection on the mtDNA coding region is confirmed and an improved molecular clock for dating human mtDNA is proposed, based on a worldwide phylogeny of > 2000 complete mtDNA genomes and calibrating against recent evidence for the divergence time of humans and chimpanzees.
Abstract: There is currently no calibration available for the whole human mtDNA genome, incorporating both coding and control regions. Furthermore, as several authors have pointed out recently, linear molecular clocks that incorporate selectable characters are in any case problematic. We here confirm a modest effect of purifying selection on the mtDNA coding region and propose an improved molecular clock for dating human mtDNA, based on a worldwide phylogeny of > 2000 complete mtDNA genomes and calibrating against recent evidence for the divergence time of humans and chimpanzees. We focus on a time-dependent mutation rate based on the entire mtDNA genome and supported by a neutral clock based on synonymous mutations alone. We show that the corrected rate is further corroborated by archaeological dating for the settlement of the Canary Islands and Remote Oceania and also, given certain phylogeographic assumptions, by the timing of the first modern human settlement of Europe and resettlement after the Last Glacial Maximum. The corrected rate yields an age of modern human expansion in the Americas at ∼15 kya that—unlike the uncorrected clock—matches the archaeological evidence, but continues to indicate an out-of-Africa dispersal at around 55–70 kya, 5–20 ky before any clear archaeological record, suggesting the need for archaeological research efforts focusing on this time window. We also present improved rates for the mtDNA control region, and the first comprehensive estimates of positional mutation rates for human mtDNA, which are essential for defining mutation models in phylogenetic analyses.

671 citations