Monthly Archives: June 2012
|No wonder they call it “china”!|
The invention of pottery introduced fundamental shifts in human subsistence practices and sociosymbolic behaviors. Here, we describe the dating of the early pottery from Xianrendong Cave, Jiangxi Province, China, and the micromorphology of the stratigraphic contexts of the pottery sherds and radiocarbon samples. The radiocarbon ages of the archaeological contexts of the earliest sherds are 20,000 to 19,000 calendar years before the present, 2000 to 3000 years older than other pottery found in East Asia and elsewhere. The occupations in the cave demonstrate that pottery was produced by mobile foragers who hunted and gathered during the Late Glacial Maximum. These vessels may have served as cooking devices. The early date shows that pottery was first made and used 10 millennia or more before the emergence of agriculture.
Greenland ice-core δ18O-temperature reconstructions suggest a dramatic cooling during the Younger Dryas (YD; 12.9–11.7 ka), with temperatures being as cold as the earlier Oldest Dryas (OD; 18.0–14.6 ka) despite an approximately 50 ppm rise in atmospheric CO2. Such YD cooling implies a muted Greenland climate response to atmospheric CO2, contrary to physical predictions of an enhanced high-latitude response to future increases in CO2. Here we show that North Atlantic sea surface temperature reconstructions as well as transient climate model simulations suggest that the YD over Greenland should be substantially warmer than the OD by approximately 5 °C in response to increased atmospheric CO2. Additional experiments with an isotope-enabled model suggest that the apparent YD temperature reconstruction derived from the ice-core δ18O record is likely an artifact of an altered temperature-δ18O relationship due to changing deglacial atmospheric circulation. Our results thus suggest that Greenland climate was warmer during the YD relative to the OD in response to rising atmospheric CO2, consistent with sea surface temperature reconstructions and physical predictions, and has a sensitivity approximately twice that found in climate models for current climate due to an enhanced albedo feedback during the last deglaciation.
The problem is that, when compared with other records, the Greenland Ice cores’ oxygen isotope ration does not hold. The explanation is complex and related to CO2 levels, the North American Ice Sheet (which was already in retreat) and the different composition of oxygen isotopes when they arrived from the Pacific Ocean.
Working with UW-Madison climatologist Zhengyu Liu, collaborators at the National Center for Atmospheric Research and others, Carlson found their computer climate model breaking down on the Younger Dryas.While it could reliably recreate temperatures in the Oldest Dryas — a similar cooling period about 18,000 years ago — they just couldn’t find a lever in the model that would simulate a Younger Dryas that matched the Greenland ice cores.“You can totally turn off ocean circulation, have Arctic sea ice advance all the way across the North Atlantic, and you still will have a warmer climate during the Younger Dryas than the Oldest Dryas because of the carbon dioxide,” Carlson says.By the time the Younger Dryas rolled around, there was more carbon dioxide in the air — about 50 parts per million more. The warming effects of that much CO2 overwhelmed the rest of the conditions that make the Oldest and Younger Dryas so alike, and demonstrates a heightened sensitivity for Arctic temperatures to rising greenhouse gases in the atmosphere.The researchers zeroed in on the Northern Hemisphere’s temperature outlier, Greenland ice cores, and found that the conversion of oxygen isotope ratio to temperature typically used on the ice cores did not account for the sort of crash climate change occurring during the Younger Dryas. It assumes prevailing winds and jet streams and storm tracks are providing the moisture for Greenland precipitation from the Atlantic Ocean.
“The Laurentide ice sheet, which covered much of North America down into the northern United States, is getting smaller as the Younger Dryas approaches,” Carlson says. “That’s like taking out a mountain of ice three kilometers high. As that melts, it allows more Pacific Ocean moisture to cross the continent and hit the Greenland ice sheet.” The two oceans have distinctly different ratios of oxygen isotopes, allowing for a different isotope ratio where the water falls as snow.
Hat tip: Pileta.
|Some temperature proxies for the Younger Dryas|
[Scroll down for updates]
In this case two individuals (right) from La Braña-Arintero site in Valdelugueros (León province near the Asturian border), dated to 7000 years ago, borderline with Neolithic arrival but, according to the paper, still “Mesolithic” (i.e. Epipaleolithic).
- M. Lacan found mtDNA H among Epipaleolithic Basques in 2011.
- M. Hervella found mtDNA H and U5 among pre-Neolithic Cantabrians and Basques respectively a couple of months ago.
|Pre-Neolithic mtDNA lineages found in Northern Iberia to date (all quite unquestionable)|
Update (revised): on the nuclear DNA sequences
Interestingly the study includes a large SNP sequence of the nuclear DNA of both individuals. When compared with several modern European populations (overloaded of Finnish and Tuscans, who hijack the analysis, the result is as follows:
PCA with 1KGPomni Chip Data (European Populations) and La Braña 1 (left) and La Braña 2 (right)
click to expand to original resolution (still not enough to discern Iberians by subpopulation easily)
As we can see the dimension 1 is hijacked by the Tuscan-Finnish duality, while the dimension 2 seems almost private, extending inside all populations with minor variations. This render the PCA essentially useless and meaningless. However it would seem that the La Braña individuals cluster best with some British and some of their creole cousins from Utah (CEU).
However when global tripolar comparison is made (after removing the noisy Finns), the result is:
|Figure S2. PCA with the Shotgun Data from La Braña 1 (Left) and La Braña 2 (Right) and the Worldwide Data Set from 1,000 Genomes Project,|
Interestingly the La Braña individuals not just cluster separately from Modern Europeans but they actually look “more Asian” than these. In fact, would we superimpose these PCA plots on any global one with more samples (which always takes an L shape with vortex at or near the European cluster) like this one (from Etyo Helix), the La Braña people would overlap Afghans and Gujaratis, roughly.
So it’s like the analysis performed is more perplexing than informative. Not really helpful. We can only hope that the sequences are soon released to the public domain so independent researchers can perform contrasting analysis. These PCAs alone are almost useless.
Update (Jun 29): details of the La Braña-Arintero findings:
|Close-up of Braña 1 (source)|
The cave was only excavated since 2006. Braña 1 was found in flexed position with ochre and a delimitation of the niche by rocks (but there is evidence that no earth was disposed on top of it). Braña 2 was found in non-anatomical disposal (possibly because of post burial alterations by water or people), at the bottom of a natural hole 4 m. deep, just beside the other one and with indications of being also a primary burial.
Braña 1 had no caries but erosion of some teeth in what is suggested to have been caused by the use of teeth tool. There is a serious injury in the upper jaw by piercing artifact (spear?), which healed.
Associated to Braña 2, there were found 24 perforated deer canines, possibly part of a necklace or other decoration originally.
The two burials are from almost exactly 7000 years ago. The ages are:
- Braña 1: 6980±50 calBP (5990-5740 BP – raw C14)
- Braña 2: 7030±50 calBP (6010-5800 BP – raw C14)
The assigning of the burials to ‘Mesolithic’ (Epipaleolithic) is based 100% on the datings and not on cultural elements (other than the deer canines) that are absent in this site. The ‘Mesolithic’ comparison dates from further North (Asturias) are from the 7th or 6th millennium uncalibrated but none of them is more recent than the ones from La Braña-Arintero (in fact they look as quite older):
- El Espertín (Burón): 7080±40 BP and 7790±120 BP (not calibrated)
- Los Canes: unspecified dates from the 6th millennium BP (not calibrated), where similar deer canine decorations were found also in burial context
Julio Vidal et al., LOS HOMBRES MESOLÍTICOS DE LA BRAÑA-ARINTERO(VALDELUGUEROS, LEÓN): UN HALLAZGO FUNERARIO EXCEPCIONALEN LA VERTIENTE MERIDIONAL DE LA CORDILLERA CANTÁBRICA. 2008. ··> found at Academia.edu.
Julio Vidal et al., LOS HOMBRES MESOLÍTICOS DE LA BRAÑA-ARINTERO (VALDELUGUEROS, LEÓN): EL HALLAZGO, SITUACIÓN, ASPECTOS ARQUEO-ANTROPOLÓGICOS, CRONOLOGÍA Y CONTEXTO CULTURAL ··> found at Academia.edu.
9.3% African and 90.7% Atlantic_Baltic
- 30% Southern (i.e. Eastern Mediterranean South or Arabia)
- 7% West Asian (i.e. Eastern Mediterranean North or Caucasus)
- 1% South Asian
45% Atlantic_Med, 41.6% North_European, 10.3% East_African, 1% Sub_Saharan
Update (Jul 1 – II):
|(From Dienekes’ blog – fair use of copyrighted work)|
Updates (Jul 3): strange ritual for ‘Mesolithic’ and some other DNA comparisons
The latest zombie comparison (different set of zombies) by Dienekes (scroll for updates in the already provided link) is similar to the previous (i.e. c. 90% like modern Europeans, specifically NW ones without the “Neolithic” stuff) but instead of being anomalous towards Africa it is towards East Asia. Not sure what to think other than it seems to point to some unchartered component with deep roots.
Maybe more interesting but still in the hmmmm zone is the comment at Diario de León[es] by Pablo Arias, Director of the Prehistoric Research Institute of Cantabria. Among other less important details,he argues that the burial or rather lack of it thereof (as the corpses were placed in the cave without earth covering, even if Braña 1 does display signs of intentional funerary disposition) is most anomalous, actually unique, among ‘Mesolithic’ burial practices which always included proper burial and not just disposition. My translation:
Nevertheless, he details that there are some peculiarities making it unique: like the kind of necklace found along individual number 2 and very specially the characteristic of the funerary space: corpses deposited on the floor of a selected hypogeum. “From another point of view, La Braña-Arintero provides another evidence of the spectacular increase in the number of burials in the 7th millennium a.C. and that may relfect an intensification of the territoriality in these societies”.
Pablo Arias precises that the more striking characteristic of the funerary context of La Braña-Arintero resides in the sepulchral space itself, detailing that it is an exclusively funerary site, with no link to settlements of that age. We see that a remote cavity, apparently not suited for habitation, and the corpses have been placed there in peculiar spaces, well delimited by natural space in the way of niches.
And this, as he defends in the article, is a funerary behavior that has no clear precedents in other peninsular contexts and rather reminds to behaviors more common in later periods instead.
And… what we just needed, so to say: Bushman affinities! In his latest comparison, using the DIY Harappa World calculator, Dienekes finds that the Braña composite is stubbornly >80% European (in this case 55% NE Euro and 27% Mediterranean) and some 17% (the highest figure so far!) non-European, mostly 7% Siberian and 6% Bushman (San).
|Pines from Tierra de Pinares (source)|
|Cuéllar, above the “sea of pines” (green area behind).|
AbstractIn the prehistoric green Sahara of Holocene North Africa—in contrast to the Neolithic of Europe and Eurasia—a reliance on cattle, sheep and goats emerged as a stable and widespread way of life, long before the first evidence for domesticated plants or settled village farming communities1, 2, 3. The remarkable rock art found widely across the region depicts cattle herding among early Saharan pastoral groups, and includes rare scenes of milking; however, these images can rarely be reliably dated4. Although the faunal evidence provides further confirmation of the importance of cattle and other domesticates5, the scarcity of cattle bones makes it impossible to ascertain herd structures via kill-off patterns, thereby precluding interpretations of whether dairying was practiced. Because pottery production begins early in northern Africa6 the potential exists to investigate diet and subsistence practices using molecular and isotopic analyses of absorbed food residues7. This approach has been successful in determining the chronology of dairying beginning in the ‘Fertile Crescent’ of the Near East and its spread across Europe8, 9, 10, 11. Here we report the first unequivocal chemical evidence, based on the δ13C and Δ13C values of the major alkanoic acids of milk fat, for the adoption of dairying practices by prehistoric Saharan African people in the fifth millennium bc. Interpretations are supported by a new database of modern ruminant animal fats collected from Africa. These findings confirm the importance of ‘lifetime products’, such as milk, in early Saharan pastoralism, and provide an evolutionary context for the emergence of lactase persistence in Africa.
|click to expand|
|Program of the conference (click to expand)|