Lower Pliocene hominid remains from Sterkfontein.
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Cosmogenic aluminum-26 and beryllium-10 burial dates of low-lying fossiliferous breccia in the caves at Sterkfontein, South Africa, show that associated hominid fossils accumulated in the Lower Pliocene. These dates indicate that the skeleton StW 573 and newly discovered specimens from Jacovec Cavern have much the same age: approximately 4 million years. These specimens are thus of an age similar to Australopithecus anamensis from East Africa. (+info)
Diversity in the early tertiary anthropoidean radiation in Africa.
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Between 1987 and 1991 recent field seasons in the Fayum Depression of Egypt have yielded five species and genera of primates that were earlier unknown. Three of these species and genera are described below. All these genera and species are known only from Fayum site L-41, which has been dated as of late Eocene age. In the Fayum, these 5 species from L-41 are added to 3 kinds of prosimians (1 species formally described) and 11 earlier named species of Anthropoidea. When certain undescribed species are added, the total of known Fayum primate species comes to 21, belonging to at least 10 genera, genera that, in turn, could belong to as many as seven families. This arguably represents more taxonomic diversity of primates, especially higher primates, than has been demonstrated before in one so spatially and temporally limited area. These facts argue that an important, perhaps primary, radiation of anthropoideans took place in the African Eocene. (+info)
An Early Cretaceous tribosphenic mammal and metatherian evolution.
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Derived features of a new boreosphenidan mammal from the Lower Cretaceous Yixian Formation of China suggest that it has a closer relationship to metatherians (including extant marsupials) than to eutherians (including extant placentals). This fossil dates to 125 million years ago and extends the record of marsupial relatives with skeletal remains by 50 million years. It also has many foot structures known only from climbing and tree-living extant mammals, suggesting that early crown therians exploited diverse niches. New data from this fossil support the view that Asia was likely the center for the diversification of the earliest metatherians and eutherians during the Early Cretaceous. (+info)
The Yana RHS site: humans in the Arctic before the last glacial maximum.
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A newly discovered Paleolithic site on the Yana River, Siberia, at 71 degrees N, lies well above the Arctic circle and dates to 27,000 radiocarbon years before present, during glacial times. This age is twice that of other known human occupations in any Arctic region. Artifacts at the site include a rare rhinoceros foreshaft, other mammoth foreshafts, and a wide variety of tools and flakes. This site shows that people adapted to this harsh, high-latitude, Late Pleistocene environment much earlier than previously thought. (+info)
A comparison of tooth structure in Neanderthals and early Homo sapiens sapiens: a radiographic study.
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Tooth components of 1st and 2nd erupted permanent molars were measured from standardised radiographs of Homo sapiens sapiens and Homo sapiens neanderthalensis. Enamel height was greater in Homo sapiens sapiens but pulp height and width and the height of the enamel to floor of the pulp chamber were greater in Homo sapiens neanderthalensis. Dentine height, crown width and enamel width showed similar results in the two groups. Unerupted first molars were measured to analyse the influence of function on tooth components and the results obtained were always within the range measured for the erupted teeth. Discriminant analysis between groups, using tooth components, showed accuracy of 93% for identification of Homo sapiens sapiens and 94% for identification of Homo sapiens neanderthalensis. The results support the hypothesis of a distinct evolutionary line for the Neanderthals. (+info)
Late Miocene teeth from Middle Awash, Ethiopia, and early hominid dental evolution.
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Late Miocene fossil hominid teeth recovered from Ethiopia's Middle Awash are assigned to Ardipithecus kadabba. Their primitive morphology and wear pattern demonstrate that A. kadabba is distinct from Ardipithecus ramidus. These fossils suggest that the last common ancestor of apes and humans had a functionally honing canine-third premolar complex. Comparison with teeth of Sahelanthropus and Orrorin, the two other named late Miocene hominid genera, implies that these putative taxa are very similar to A. kadabba. It is therefore premature to posit extensive late Miocene hominid diversity on the basis of currently available samples. (+info)
Wild chimpanzee dentition and its implications for assessing life history in immature hominin fossils.
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Data from three African field sites on Pan troglodytes demonstrate an unambiguous pattern of a slower growth rate in wild vs. captive chimpanzee populations. A revised dental growth chronology for chimpanzees is similar to estimated timing of Homo erectus and therefore has implications for interpreting life history in hominins. (+info)
Older age becomes common late in human evolution.
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Increased longevity, expressed as number of individuals surviving to older adulthood, represents one of the ways the human life history pattern differs from other primates. We believe it is a critical demographic factor in the development of human culture. Here, we examine when changes in longevity occurred by assessing the ratio of older to younger adults in four hominid dental samples from successive time periods, and by determining the significance of differences in these ratios. Younger and older adult status is assessed by wear seriation of each sample. Whereas there is significant increased longevity between all groups, indicating a trend of increased adult survivorship over the course of human evolution, there is a dramatic increase in longevity in the modern humans of the Early Upper Paleolithic. We believe that this great increase contributed to population expansions and cultural innovations associated with modernity. (+info)