Beringia and the peopling of the Western Hemisphere

Did Beringian environments represent an ecological barrier to humans until less than 15 000 years ago or was access to the Americas controlled by the spatial–temporal distribution of North American ice sheets? Beringian environments varied with respect to climate and biota, especially in the two major areas of exposed continental shelf. The East Siberian Arctic Shelf (‘Great Arctic Plain’ (GAP)) supported a dry steppe-tundra biome inhabited by a diverse large-mammal community, while the southern Bering-Chukchi Platform (‘Bering Land Bridge’ (BLB)) supported mesic tundra and probably a lower large-mammal biomass. A human population with west Eurasian roots occupied the GAP before the Last Glacial Maximum (LGM) and may have accessed mid-latitude North America via an interior ice-free corridor. Re-opening of the corridor less than 14 000 years ago indicates that the primary ancestors of living First Peoples, who already had spread widely in the Americas at this time, probably dispersed from the NW Pacific coast. A genetic ‘arctic signal’ in non-arctic First Peoples suggests that their parent population inhabited the GAP during the LGM, before their split from the former. We infer a shift from GAP terrestrial to a subarctic maritime economy on the southern BLB coast before dispersal in the Americas from the NW Pacific coast

Geoarchaeological and bioarchaeological studies at Mira, an early Upper Paleolithic site in the Lower Dnepr Valley, Ukraine

New geoarchaeological and bioarcheological research was undertaken at the open-air site of Mira, which is buried in deposits of the Second Terrace of the Dnepr River, roughly 15 km downstream from the city of Zaporozhye in Ukraine. Previous excavation of the site revealed two occupation layers dating to ∼32,000 cal BP. The lower layer (II/2) yielded bladelets similar to those of the early Gravettian, while the upper layer (I) contained traces of an artificial shelter and hundreds of bones and teeth of horse (Equus latipes). Mira represents the only firmly dated early Upper Paleolithic (EUP) site in the Dnepr Basin, and occupies a unique topographic setting for the EUP near the center of the broad floodplain of the Dnepr River. The site was visited during a period of floodplain stability, characterized by overbank deposition and weak soil formation under cool climate conditions. Mira was used as a long-term camp, but also was the locus of large-mammal carcass processing associated with a nearby kill of a group of horses (Layer I)

Supra-regional correlations of the most ancient paleosols and Paleolithic layers of Kostenki-Borschevo region (Russian Plain)

International audienceThe archaeological site Kostenki12, located on the Middle Don River, provides a key stratigraphic profile for regional paleopedological, paleoenvironmental, geological and cultural sequences, containing the oldest known cultural layers of the region (layer V - Paleolithic, layer IV - Upper Paleolithic, layer III - Kostenki-Strelets culture early phase) dating to the early part of MIS3, or, in chronometric terms, to 54-42 ka. Kostenki12 complements Kostenki14 (Markina Gora), which is a key profile for the interval 42-27 ka. The new data from Kostenki12 show that the East European Upper Paleolithic began similar to 45 ka. The stratigraphy exhibits similarities to that of Borschevo5. The Kostenki12 pollen diagramis correlated with: 1) other pollen diagrams from Kostenki-Borschevo region; 2) the most detailed climatostratigraphical scale of the Russian Plain Late Pleistocene; 3) O-16/O-18 Greenland GISP2 scale; 4) C-13/C-14 record from stalagmite at Villars Cave (France), as well as with pollen records (5-7) from: 5) Lake Monticchio (Italy), 6) southern Black Sea (M72/5-25-GC1) and 7) Glinde and Moershoofd (northern Germany). The results of the supra-regional paleoenvironmental correlations demonstrate that the lowest Paleolithic layer V and paleosol D, characterized by elm dominance, correlate to the second half of the optimum of the Glinde interstadial at 51-48 ka, corresponding to DO 14. The earliest Upper Paleolithic layer IV and paleosol B, characterized by coexistence of elm forests and wet meadows, began to form during the second part of the Moershoofd interstadial optimum at 46-44 ka, correlating with DO 12. Paleosol A and layer III (Kostenki-Strelets culture) began to form after the abrupt end of the Moershoofd interstadial similar to 43.5 ka, during unstable conditions, according to pollen and paleozoological data (steppe with horse dominance and later spruce forest tundra with reindeer dominance in paleozoological complex). These correlations provide more accurate dating of the Paleolithic layers and paleosols at Kostenki-Borschevo, suggesting that previously reported radiocarbon dates on units below CI tephra layer are too young, but that the OSL chronology is generally accurate. (C) 2014 Elsevier Ltd and INQUA. All rights reserved

Environmental selection during the last ice age on the mother-to-infant transmission of vitamin D and fatty acids through breast milk

Because of the ubiquitous adaptability of our material culture, some human populations have occupied extreme environments that intensified selection on existing genomic variation. By 32,000 years ago, people were living in Arctic Beringia, and during the Last Glacial Maximum (LGM; 28,000-18,000 y ago), they likely persisted in the Beringian refugium. Such high latitudes provide only very low levels of UV radiation, and can thereby lead to dangerously low levels of biosynthesized vitamin D. The physiological effects of vitamin D deficiency range from reduced dietary absorption of calcium to a compromised immune system and modified adipose tissue function. The ectodysplasin A receptor (EDAR) gene has a range of pleiotropic effects, including sweat gland density, incisor shoveling, and mammary gland ductal branching. The frequency of the human-specific EDAR V370A allele appears to be uniquely elevated in North and East Asian and New World populations due to a bout of positive selection likely to have occurred circa 20,000 y ago. The dental pleiotropic effects of this allele suggest an even higher occurrence among indigenous people in the Western Hemisphere before European colonization. We hypothesize that selection on EDAR V370A occurred in the Beringian refugium because it increases mammary ductal branching, and thereby may amplify the transfer of critical nutrients in vitamin D-deficient conditions to infants via mothers' milk. This hypothesized selective context for EDAR V370A was likely intertwined with selection on the fatty acid desaturase (FADS) gene cluster because it is known to modulate lipid profiles transmitted to milk from a vitamin D-rich diet high in omega-3 fatty acids