Protein preservation and DNA retrieval from ancient tissues. (1/404)

The retrieval of DNA from fossils remains controversial. To substantiate claims of DNA recovery, one needs additional information on the preservation of other molecules within the same sample. Flash pyrolysis with GC and MS was used to assess the quality of protein preservation in 11 archaeological and paleontological remains, some of which have yielded ancient DNA sequences authenticated via a number of criteria and some of which have consistently failed to yield any meaningful DNA. Several samples, including the Neanderthal-type specimen from which DNA sequences were recently reported, yielded abundant pyrolysis products assigned to 2,5-diketopiperazines of proline-containing dipeptides. The relative amounts of these products provide a good index of the amount of peptide hydrolysis and DNA preservation. Of these samples, four stem from arctic or subarctic regions, emphasizing the importance of cooler temperatures for the preservation of macromolecules. Flash pyrolysis with GC and MS offers a rapid and effective method for assessing fossils for the possibility of DNA preservation.  (+info)

Why hunter-gatherer populations do not show signs of pleistocene demographic expansions. (2/404)

The mitochondrial DNA diversity of 62 human population samples was examined for potential signals of population expansions. Stepwise expansion times were estimated by taking into account heterogeneity of mutation rates among sites. Assuming an mtDNA divergence rate of 33% per million years, most populations show signals of Pleistocene expansions at around 70,000 years (70 KY) ago in Africa and Asia, 55 KY ago in America, and 40 KY ago in Europe and the Middle East, whereas the traces of the oldest expansions are found in East Africa (110 KY ago for the Turkana). The genetic diversity of two groups of populations (most Amerindian populations and present-day hunter-gatherers) cannot be explained by a simple stepwise expansion model. A multivariate analysis of the genetic distances among 61 populations reveals that populations that did not undergo demographic expansions show increased genetic distances from other populations, confirming that the demography of the populations strongly affects observed genetic affinities. The absence of traces of Pleistocene expansions in present-day hunter-gatherers seems best explained by the occurrence of recent bottlenecks in those populations, implying a difference between Pleistocene (approximately 1,800 KY to 10 KY ago) and Holocene (10 KY to present) hunter-gatherers demographies, a difference that occurred after, and probably in response to, the Neolithic expansions of the other populations.  (+info)

Neanderthal cannibalism at Moula-Guercy, Ardeche, France. (3/404)

The cave site of Moula-Guercy, 80 meters above the modern Rhone River, was occupied by Neanderthals approximately 100,000 years ago. Excavations since 1991 have yielded rich paleontological, paleobotanical, and archaeological assemblages, including parts of six Neanderthals. The Neanderthals are contemporary with stone tools and faunal remains in the same tightly controlled stratigraphic and spatial contexts. The inference of Neanderthal cannibalism at Moula-Guercy is based on comparative analysis of hominid and ungulate bone spatial distributions, modifications by stone tools, and skeletal part representations.  (+info)

Mid-Pleistocene Acheulean-like stone technology of the Bose basin, South China. (4/404)

Stone artifacts from the Bose basin, South China, are associated with tektites dated to 803,000 +/- 3000 years ago and represent the oldest known large cutting tools (LCTs) in East Asia. Bose toolmaking is compatible with Mode 2 (Acheulean) technologies in Africa in its targeted manufacture and biased spatial distribution of LCTs, large-scale flaking, and high flake scar counts. Acheulean-like tools in the mid-Pleistocene of South China imply that Mode 2 technical advances were manifested in East Asia contemporaneously with handaxe technology in Africa and western Eurasia. Bose lithic technology is associated with a tektite airfall and forest burning.  (+info)

Rapid extinction of the moas (Aves: Dinornithiformes): model, test, and implications. (5/404)

A Leslie matrix population model supported by carbon-14 dating of early occupation layers lacking moa remains suggests that human hunting and habitat destruction drove the 11 species of moa to extinction less than 100 years after Polynesian settlement of New Zealand. The rapid extinction contrasts with models that envisage several centuries of exploitation.  (+info)

The initial domestication of goats (Capra hircus) in the Zagros mountains 10,000 years ago. (6/404)

Initial goat domestication is documented in the highlands of western Iran at 10,000 calibrated calendar years ago. Metrical analyses of patterns of sexual dimorphism in modern wild goat skeletons (Capra hircus aegagrus) allow sex-specific age curves to be computed for archaeofaunal assemblages. A distinct shift to selective harvesting of subadult males marks initial human management and the transition from hunting to herding of the species. Direct accelerator mass spectrometry radiocarbon dates on skeletal elements provide a tight temporal context for the transition.  (+info)

Pleistocene milestones on the out-of-Africa corridor at Gesher Benot Ya'aqov, israel. (7/404)

The Acheulean site of Gesher Benot Ya'aqov in the Dead Sea Rift of Israel documents hominin movements and technological development on a corridor between Africa and Eurasia. New age data place the site at 780,000 years ago (oxygen isotope stage 19), considerably older than previous estimates. The archaeological data from the site portray strong affinities with African stone tool traditions. The findings also reflect adroit technical skills and in-depth planning abilities, more advanced and complex than those of earlier archaeological occurrences in the Levant.  (+info)

Peopling the past: new perspectives on the ancient Maya. (8/404)

The new direction in Maya archaeology is toward achieving a greater understanding of people and their roles and their relations in the past. To answer emerging humanistic questions about ancient people's lives Mayanists are increasingly making use of new and existing scientific methods from archaeology and other disciplines. Maya archaeology is bridging the divide between the humanities and sciences to answer questions about ancient people previously considered beyond the realm of archaeological knowledge.  (+info)