Late Holocene climate change and human impact recorded in a south Swedish ombrotrophic peat bog

A peat core from a raised bog in southern Sweden was examined (plant macrofossils, pollen/non-pollen microfossils, colorimetric humification, carbon/nitrogen ratios, bulk densities, loss on ignition) to investigate the effects of climate change and human impact on the plant species composition and carbon accumulation of the peat forming vegetation. ¹⁴C wiggle-match dating was applied for fine-resolution dating. Cooling at the start of the Little Ice Age was reflected by a decline of thermophilous trees from the pollen record between ca. cal AD 1275–1590, coinciding with increases in atmospheric Δ¹⁴C pointing to decreases of solar activity (Wolf and Spörer minimum). Human impact also decreased. Later, the effect of human impact was clearly visible in the form of a black brown, decomposed peat layer, the top of which marks a gap of more than 300 years. Artificial drainage probably caused secondary decomposition and oxidation of the peat. From ca. cal AD 1960 the water table of the peat bog was restored following construction of a road and raised bog vegetation regenerated.     

The age of the Kaali meteorite craters and the effect of the impact on the environment and man: evidence from inside the Kaali craters,island of Saaremaa,Estonia

The Kaali meteorite impact crater field, which consists of a 110 m diameter main crater and eight satellite craters on the island of Saaremaa, Estonia is a unique object as its meteoritic origin is well proven, it lies in a densely populated area and fell in the relatively recent past. The precise age of the impact that generated the craters is still disputed. We investigated the basal sediment section from the main crater lake, Kaali järv, consisting of crushed and in-washed dolomite diamiction. AMS dating of terrestrial macrofossils from these sediment layers places the age of the impact at 1690–1510 B.C. The age is about 1000 years older than revealed from the impact marker-horizon in a contemporaneous peat sequence 6 km northwest of the Kaali crater. The pollen, diatom and chemical data suggest the instant formation of a shallow hard-water lake environment in the main crater depression after the impact, and a rapid post-impact sedimentation of crushed dolomite dust. Archaeological evidence on the crater slopes points to human activity around 700–200 B.C., indicating that the crater ring wall was inhabited by Bronze Age people soon after the impact event, and the structure of the main crater is mimicked in nearby archaeological sites.

U-series and ESR analyses of bones and teeth relating to the human burials from Skhul

In order to resolve long-standing issues surrounding the age of the Skhul early modern humans, new analyses have been conducted, including the dating of four well-provenanced fossils by ESR and U-series. If the Skhul burials took place within a relatively short time span, then the best age estimate lies between 100 and 135 ka. This result agrees very well with TL ages obtained from burnt flint of 119+/-18 ka (Mercier et al., 1993). However, we cannot exclude the possibility that the material associated with the Skhul IX burial is older than those of Skhul II and Skhul V. These and other recent age estimates suggest that the three burial sites, Skhul, Qafzeh and Tabun are broadly contemporaneous, falling within the time range of 100 to 130 ka. The presence of early representatives of both early modern humans and Neanderthals in the Levant during Marine Isotope Stage 5 inevitably complicates attempts at segregating these populations by date or archaeological association. Nevertheless, it does appear that the oldest known symbolic burials are those of early modern humans at Skhul and Qafzeh. This supports the view that, despite the associated Middle Palaeolithic technology, elements of modern human behaviour were represented at Skhul and Qafzeh prior to 100 ka.     

黑龙江十八站遗址的新材料与年代

黑龙江省十八站遗址经过再次调查发掘,地层中出土石制品38件,地表采集20件。石核具有修理台面和对向剥片的技术,石片中石叶技术特征明显,石叶技术与水洞沟遗址相近,石器以轻型为主,主要类型为刮削器。采集的两面器和端刮削器则在华北地区、俄罗斯远东地区南部的几个遗址中有相似标本发现。采用光释光的方法对遗址的绝对年代进行测定,结果为距今2.5—1万年。     

A review of the chronology of the European Middle Pleistocene hominid record

Over the last seventy years, European hominid fossils and associated archaeological remains have been dated by reference to the classical, fourfold glacial/interglacial subdivision of the Pleistocene. This method seemed relatively straightforward and precise especially as new discoveries were fitted into the schemes, apparently strengthening the correlations and increasing their validity. However, recent studies of deep-sea cores and terrestrial deposits, combined with new developments in relative and absolute dating, have shown that the fourfold schemes are oversimplified. This paper critically reviews some of the dating evidence from sites with hominid remains generally considered as Middle Pleistocene (ca. 700,000–128,000 BP). The hominid and archaeological remains are shown to require independent dating and a cautious approach is adopted towards the use of mammalian faunal remains as chronological indicators. The techniques and results of absolute dating are discussed with reference to present problems and future prospects. At a time of transition from an old framework to new correlations, it is inevitable that some conclusions seem tentative and others rather negative. Nevertheless, the Middle Pleistocene in Europe is more fully understood and better dated than the equivalent period in other parts of the world.     

Nouvelles données sur la chronologie des sites paléolithiques en contexte lœssique du Nord-Est et du Sud-Est de la Roumanie (Périphérie orientale des Carpates)

In the present study, the chronology of several intraloessic Upper and Middle Palaeolithic sites, located in Moldova, Dobrogea and the eastern Danube Plain, is re-examined and better defined on the basis of new chronological data (IRSL ages on loess, ESR/U-Th ages on teeth) and also biostratigraphic and pedostratigraphic evidence. Middle Palaeolithic occupations have been identified in the MIS 6 loess L2 (interstadial episode), the MIS 7 pedocomplex S2 and the red soils S3 presumably assigned to MIS 9. These results are questioning the chronological extension of the Middle Palaeolithic in Romania which until early 2000 (Păunescu, 1999 a, b; Cârciumaru, 1999) was restricted to the Upper Pleistocene (short chronology: 130–35 ka; MIS 5-MIS 3). Hence, we demonstrate herein that Humans were already present during the Middle Pleistocene at the eastern periphery of the Carpathian Mountains, along the Danube valley and its tributary, the Prut River.     

Empirical calibrated radiocarbon sampler: a tool for incorporating radiocarbon‐date and calibration error into Bayesian phylogenetic analyses of ancient DNA

Studies of DNA from ancient samples provide a valuable opportunity to gain insight into past evolutionary and demographic processes. Bayesian phylogenetic methods can estimate evolutionary rates and timescales from ancient DNA sequences, with the ages of the samples acting as calibrations for the molecular clock. Sample ages are often estimated using radiocarbon dating, but the associated measurement error is rarely taken into account. In addition, the total uncertainty quantified by converting radiocarbon dates to calendar dates is typically ignored. Here, we present a tool for incorporating both of these sources of uncertainty into Bayesian phylogenetic analyses of ancient DNA. This empirical calibrated radiocarbon sampler (ECRS) integrates the age uncertainty for each ancient sequence over the calibrated probability density function estimated for its radiocarbon date and associated error. We use the ECRS to analyse three ancient DNA data sets. Accounting for radiocarbon‐dating and calibration error appeared to have little impact on estimates of evolutionary rates and related parameters for these data sets. However, analyses of other data sets, particularly those with few or only very old radiocarbon dates, might be more sensitive to using artificially precise sample ages and should benefit from use of the ECRS.