Showing posts with label Geology. Show all posts
Showing posts with label Geology. Show all posts

August 06, 2016

China's Great Flood and the rise of the Xia dynasty

From a related story: Massive flood may have led to China's earliest empire:
Many cultures trace their origins to the hazy horizon where history meets legend. In China's case, that blurry line occurs sometime between 2200 B.C.E. and 2000 B.C.E., when a legendary hero named Yu tamed Yellow River flooding and earned a mandate to become the founding emperor of the Xia dynasty, the country's first. That’s the story according to texts written long after the fact, and many Chinese believe their civilization started with emperor Yu. But archaeologists have been unable to find convincing evidence for either the flood or the Xia dynasty itself. 
... 
The massive flood “provides us with a tantalizing hint that the Xia dynasty might really have existed," says David Cohen, an archaeologist and co-author at National Taiwan University in Taipei. The devastating flood could have inundated settlements even a thousand or more kilometers downstream, he says, and created chaos from which a new political order emerged. This sequence of events neatly fits the legend of Yu controlling the flooding by dredging channels to confine the Yellow River and its tributaries. This feat, the ancient texts say, allowed him to claim a mandate as the first emperor of the Xia dynasty.  
The timing is curiously coincidental. Around 1900 B.C.E., Cohen says, Chinese society was transitioning from the Neolithic to the Bronze age. The date also correlates with what is called the Erlitou culture, which is known from palace buildings and bronze smelting workshops discovered near Zhengzhou, about 2500 kilometers downstream from Jishi Gorge. Many scholars have argued that Erlitou is a manifestation of the elusive Xia dynasty, but a link is not firmly established.

Science 05 Aug 2016: Vol. 353, Issue 6299, pp. 579-582 DOI: 10.1126/science.aaf0842

Outburst flood at 1920 BCE supports historicity of China’s Great Flood and the Xia dynasty

Qinglong Wu

China’s historiographical traditions tell of the successful control of a Great Flood leading to the establishment of the Xia dynasty and the beginning of civilization. However, the historicity of the flood and Xia remain controversial. Here, we reconstruct an earthquake-induced landslide dam outburst flood on the Yellow River about 1920 BCE that ranks as one of the largest freshwater floods of the Holocene and could account for the Great Flood. This would place the beginning of Xia at ~1900 BCE, several centuries later than traditionally thought. This date coincides with the major transition from the Neolithic to Bronze Age in the Yellow River valley and supports hypotheses that the primary state-level society of the Erlitou culture is an archaeological manifestation of the Xia dynasty.

Link

March 20, 2015

Campanian Ignibrite and Neandertal demise

Geology doi:10.1130/G36514.1

Campanian Ignimbrite volcanism, climate, and the final decline of the Neanderthals

Benjamin A. Black1, Ryan R. Neely2,3,4 and Michael Manga1

The eruption of the Campanian Ignimbrite at ca. 40 ka coincided with the final decline of Neanderthals in Europe. Environmental stress associated with the eruption of the Campanian Ignimbrite has been invoked as a potential driver for this extinction as well as broader upheaval in Paleolithic societies. To test the climatic importance of the Campanian eruption, we used a three-dimensional sectional aerosol model to simulate the global aerosol cloud after release of 50 Tg and 200 Tg SO2. We coupled aerosol properties to a comprehensive earth system model under last glacial conditions. We find that peak cooling and acid deposition lasted one to two years and that the most intense cooling sidestepped hominin population centers in Western Europe. We conclude that the environmental effects of the Campanian Ignimbrite eruption alone were insufficient to explain the ultimate demise of Neanderthals in Europe. Nonetheless, significant volcanic cooling during the years immediately following the eruption could have impacted the viability of already precarious populations and influenced many aspects of daily life for Neanderthals and anatomically modern humans.

Link

February 22, 2015

Multiple opportunities for Out-of-Africa

Geology doi: 10.1130/G36401.1

Alluvial fan records from southeast Arabia reveal multiple windows for human dispersal

Ash Parton et al.

The dispersal of human populations out of Africa into Arabia was most likely linked to episodes of climatic amelioration, when increased monsoon rainfall led to the activation of drainage systems, improved freshwater availability, and the development of regional vegetation. Here we present the first dated terrestrial record from southeast Arabia that provides evidence for increased rainfall and the expansion of vegetation during both glacial and interglacial periods. Findings from extensive alluvial fan deposits indicate that drainage system activation occurred during Marine Isotope Stage (MIS) 6 (ca. 160–150 ka), MIS 5 (ca. 130–75 ka), and during early MIS 3 (ca. 55 ka). The development of active freshwater systems during these periods corresponds with monsoon intensity increases during insolation maxima, suggesting that humid periods in Arabia were not confined to eccentricity-paced deglaciations, and providing paleoenvironmental support for multiple windows of opportunity for dispersal out of Africa during the late Pleistocene.

Link

May 14, 2014

Younger Dryas/Cosmic Impact synchrony questioned

Good coverage in Nature News:
Supporters of the impact theory have put forth 29 sites, from North America to Europe and beyond, that contain a thin layer of sediments said to date to the start of the cosmic impact event. The latest study checked to see whether those sites were all really 12,800 years old.  
Only 3 of the 29 are, the researchers report today in the Proceedings of the National Academy of Sciences1. The other sites either have not been dated using the usual radiometric methods, or are much older or younger than the reported impact. “The chronology doesn’t hold up,” says team leader David Meltzer, an archaeologist at Southern Methodist University in Dallas, Texas.
but:
Impact supporters are not about to give up. “Meltzer’s analysis of the dates is overly simplistic and clearly biased towards his conclusions,” says Richard Firestone, a nuclear chemist at Lawrence Berkeley National Laboratory in California and leader of the impact theory. Errors in radiocarbon dating mean that not all of the sites will date precisely to 12,800 years ago, Firestone argues. And much of his team's argument relies on cross-correlating various sites containing impact markers, some with good radiocarbon dates and some without.
PNAS doi: 10.1073/pnas.1401150111

Chronological evidence fails to support claim of an isochronous widespread layer of cosmic impact indicators dated to 12,800 years ago

David J. Meltzer et al.

A key element underpinning the controversial hypothesis of a widely destructive extraterrestrial impact at the onset of the Younger Dryas is the claim that 29 sites across four continents yield impact indicators all dated to 12,800 ± 150 years ago. This claim can be rejected: only three of those sites are dated to this window of time. At the remainder, the supposed impact markers are undated or significantly older or younger than 12,800 years ago. Either there were many more impacts than supposed, including one as recently as 5 centuries ago, or, far more likely, these are not extraterrestrial impact markers.

Link

May 01, 2014

Doggerland inhabitants destroyed by tsunami (?)

I hope someone is studying ancient DNA from these two Mesolithic ladies from Brittany. The caption reads:
These two young Mesolithic women from Teviec, Brittany, were brutally murdered. As sea levels rose there may have been increased competition for resources
Prehistoric North Sea 'Atlantis' hit by 5m tsunami
The wave was generated by a catastrophic subsea landslide off the coast of Norway.
Analysis suggests the tsunami over-ran Doggerland, a low-lying landmass that has since vanished beneath the waves. 
"It was abandoned by Mesolithic tribes about 8,200 years ago, which is when the Storegga slide happened," said Dr Jon Hill from Imperial College London. 

The wave could have wiped out the last people to occupy this island. 
The research has been submitted to the journal Ocean Modelling and is being presented at the European Geosciences Union General Assembly in Vienna this week.
Dr Hill and his Imperial-based colleagues Gareth Collins, Alexandros Avdis, Stephan Kramer and Matthew Piggott used computer simulations to explore the likely effects of the Norwegian landslide. 
He told BBC News: "We were the first ever group to model the Storegga tsunami with Doggerland in place. Previous studies have used the modern bathymetry (ocean depth)."
As such, the study gives the most detailed insight yet into the likely impacts of the huge landslip and its associated tsunami wave on this lost landmass.

September 12, 2013

Rivers across the Sahara

PLoS ONE 8(9): e74834. doi:10.1371/journal.pone.0074834

Were Rivers Flowing across the Sahara During the Last Interglacial? Implications for Human Migration through Africa

Tom J. Coulthard et al.

Human migration north through Africa is contentious. This paper uses a novel palaeohydrological and hydraulic modelling approach to test the hypothesis that under wetter climates c.100,000 years ago major river systems ran north across the Sahara to the Mediterranean, creating viable migration routes. We confirm that three of these now buried palaeo river systems could have been active at the key time of human migration across the Sahara. Unexpectedly, it is the most western of these three rivers, the Irharhar river, that represents the most likely route for human migration. The Irharhar river flows directly south to north, uniquely linking the mountain areas experiencing monsoon climates at these times to temperate Mediterranean environments where food and resources would have been abundant. The findings have major implications for our understanding of how humans migrated north through Africa, for the first time providing a quantitative perspective on the probabilities that these routes were viable for human habitation at these times.

Link

ESHE 2013 abstracts

219 pages worth of abstracts from the upcoming meeting of the European Society for the study of Human Evolution (pdf).

I will post some excerpts:

Evolutionary History And Biological Diversity Of Homo Sapiens In Southeast Asia: Contour Shape Analysis Of Modern Human Upper Molars:


The evolutionary history and the pattern of biological diversity of modern humans in Southeast Asia has long been regarded as resulting of two major migrations waves. In this hypothesis it is generally considered that a first wave of migration (generally referred as “Australo-Melanesians”) reached Australia around 60000 BP while the second wave (often referred as “Mongoloids”) is correlated to a demic diffusion of the Neolithic from a Southeast China homeland which started around mid-Holocene. ... Our results also bring very interesting perspectives concerning the detection of the signature of a possible Denisovan admixture in the phenotype of modern human populations. Indeed, past and recent modern human groups which are hypothetically sharing Denisovan ancestry have closer phenetic affinities with each other than with other populations.

Podium Presentation: Session 9, Sa (14:20) A fine scale survey of the worldwide similarity between humans and archaic hominids and its implication on the proposed admixture scenario 
Since the publications of Green et al. 2010 and Reich et al. 2010, several investigations have followed suit addressing the question regarding anatomically modern human and archaic hominin admixture. The genetic analyses of the Neanderthal draft genome and the Denisova genome concluded that these archaic hominins made a 1-4% contribution to non-African populations and 4-6% contribution to Melanesian populations, respectively. The argument of whether the observed genetic similarity is consistent with admixture or ancient substructure is still under debate. While observations have been consistent with an admixture scenario of Neanderthals and the ancestors of non-Africans coming into contact 50 80 kya in the Middle East, the lack of power in these experiments falter in providing reliable results. Here we look at the relationship between AMH and these archaic hominins on a fine-scale level by using several methods (including revised D-statistic) on the Neanderthal draft genome, Denisova high-coverage genome, and a collection of published and unpublished genotype and sequence data. We use our findings to clarify the proposed admixture scenario as well as discuss new findings in newly analyzed comparisons of African, South Asian and American populations with archaic hominins, Neanderthal and Denisova. Our results shed light on understanding the observed genetic similarity within and between humans (African and non-African) and archaic hominins, particularly in relevance to the admixture versus ancient substructure scenarios. 

How modern are the earliest Homo sapiens? 
Previous research (reviewed in Trinkaus, 2005) has suggested that the African and western Asian contemporaries of Neandertals, generally considered to be the earliest Homo sapiens, are not particularly modern looking in their cranial anatomy. Here we test whether the dental morphological signal agrees with this assessment. We examined and recorded dental morphological variation in the earliest H. sapiens and asked: how modern are they dentally? We used a Bayesian statistical approach to classifying individuals into two possible groups based on dental non-metric traits. e classification was based on dental trait frequencies and sample sizes for two known samples of 120 Neandertals and 106 Upper Paleolithic H. sapiens individuals. A cross- validation test of these individuals resulted in a correct classification rate of 95%, which is even better than the results of a previous study using the same method based on fewer individuals (Bailey et al 2009). Our early H. sapiens sample included 41 individuals from Southern Africa (Die Kelders, Klasies River Mouth and Equus Cave), Northern Africa (Temara, El Harhoura, Dar es Soltan) and the Levant (Qafzeh, Skhul). We treated our early H. sapiens individuals as unknown and calculated the probability that each belonged to either the Upper Paleolithic or Neandertal sample. While understanding that technically these individuals did not belong to either group, we hypothesized that if the earliest H. sapiens were already dentally modern then, when forced into a group, they should fall into the Upper Paleolithic H. sapiens group. We also hypothesized that if there had been significant admixture in the Levant during the initial dispersal out of Africa - as has been sometimes proposed based on paleontological - and more recently on genetic - evidence (Green et al 2010) that these samples would have the largest proportion of individuals classified as Neandertal. Our results indicated that this was not the case. While a surprising number (27%) of early H. sapiens did classify as Neandertal, the smallest proportion of these came from the Levant (7% - one out of 14 individuals). The African sample was more of a mixed bag. None of the individuals from Die Kelders or Klaises River Mouth classified as Neandertal, while four out of five of the individuals from Equus Cave did. Moreover, 6 out of 13 (46%) of the Northern African individuals were classified as Neandertal. An inspection of the individual specimens that classified as Neandertals revealed that in most cases it is the predominance of primitive features, rather than derived Neandertal traits, that is driving the classification. We conclude (1) by the time the earliest H. sapiens dispersed from Africa they had already attained a more-or-less modern dental pattern; (2) in the past, as is the case today, Late Pleistocene Africans were not a homogeneous group, some retained primitive dental traits in higher proportions than others. Furthermore, we acknowledge that while our method is an excellent tool for discriminating between Upper Paleolithic H. sapiens and Neandertals, it may not be appropriate for testing Neandertal H. sapiens admixture because all traits (primitive and derived) are weighed equally. 

The potential for catastrophic impact of the Campanian Ignimbrite (CI) tephra on human evolution: new data from the Lower Danube loess steppe:
Here we investigate an unexpectedly thick CI tephra deposit at Urluia in the southeast Romanian loess steppe, 1200 km from the super-eruption vent in Italy. Existing models suggest that the CI tephra thickness might reach a maximum 5-10 cm in Eastern Europe; the Urluia ash deposit is up to 100 cm thick. Additional, recently discovered Lower Danube sites also reveal substantially thicker than modelled CI ash beds. 
Radiocarbon dating the extinction of European Neanderthals

The transitional industries and their makers:
The demonstration of modern settlements pre-dating the earliest Aurignacian in Europe has important implications (Hublin 2012). It is consistent with a patchy pattern of modern colonization, with some significant chronological overlap between Neandertals and modern humans on a continental scale. In this model innovations observed in the Neandertal world around or after 50 ka cal BP may have resulted from cultural diffusion triggered by these influxes of populations into western Eurasia.
The Upper Paleolithic of the Ikh Tulberin Gol (Northern Mongolia): new excavations at the Tolbor 16 open-air site:
Numerous questions remain regarding the timing and the context of Upper Paleolithic emergence in Northeast Asia. Available data allow the recognition of a form of Initial Upper Paleolithic (IUP) (Brantingham et al, 2001) documented in the Altai circa 45-40 ka uncal BP (Goebel et al., 1993, Derevianko et al, 2000, Zwyns et al., 2012), in the Cis- and Transbaikal around 40 ka uncal BP (Lbova, 2008) ...
New data on the radiocarbon chronology of the Stretleskayan at Kostenki (Voronezh, Central Russia) :
It concerns cultural layer III at Kostenki 12 and cultural layer V at Kostenki I, respectively previously dated 36,280±360 and 34,900 ±350 BP in Groningen (Damblon et al., 1996). ... Remaining material of the charcoal sample from cultural layer III at Kostenki 12, previously dated 36,280 ±250 BP, was also submitted for dating to Oxford with ABOx-SC pretreatment. the results show that the two Groningen dates and the three Oxford dates are in good agreement and fit within a time interval of 1 millennium, but provide ages several millennia older than the ages obtained previously. Taking into account this new chronology, the appearance of the Stretleskayan at Kostenki will be compared with the chronological background of the Early Aurignacian, Szeletian and Bohunician occurrences in the MiddleDanube sequence, also based on ABA and ABOx-SC cross-dating (Haesaerts et al., 2013). 

Two Waves of Paleolithic Settlers Migrations to North West Beringia in Pleistocene End (End of Karginsky Interstadial) :
Way of 1st wave is marked by sites Afontova Gora V, Ust-Kova on Angara, than along Lena river up to Central Ykut plain, turn Aldan (Ikhine I etc), than round Kolyma plain to Chukotka, where they left abt 30 Ka Orlovka II site in North of West and Kymyneykey site in North of East Chukotka. In Aldan basin migration slowly down. Its reason could be glaciation of Verkhoyansk and Chersky ranges. During this delay “technical re-equipment” happened of migrations. Orlovka II and Kymyney artefacts are clear Aldan. 2nd wave migration was abt 29-28 Ka during final karginsky (middle: würm, wisconsin) warming, when paleoclimate along all northern outskirts of Asia was like to recent or more warm (Drozdov and Laukhin, 2010). Migrants of 2nd wave went to Yana mouth and left here site. Artifacts of this site don’t have Aldanian traditions, but are very close to Yeniseisk. There were little of favorable niches to North of South Mountain Belt; and their demographic capacity were nor big. 
Modern human dispersal into Eurasia: Preliminary results of the multi-disciplinary project on the replacement of Neanderthals by modern humans (RNMH)
Both the chronometric dating and the geographic distribution of archaeological entities indicate that modern human populations equipped themselves with blade products based on the Levallois method, a technology that emerged in North Africa (Taramsan) around 60 ka and then dispersed into the Eastern Mediterranean Levant (Emiran) between 49 and 48 ka. Blade technology further expanded into Eastern and Central Europe (Bachokirian and Bohunician) between 48 and 45 ka and into Southern Siberia (Kara-Bom horizons 6 and 5) at around 47 ka. The rapid expansion of modern humans into Western and Eastern Eurasia followed by the demise of archaic populations in these regions may imply technological and cognitive advantages of modern humans. 

July 25, 2013

Middle Paleolithic and Neolithic occupations around Mundafan palaeolake (Crassard et al. 2013)

From the paper:
Survey in the Mundafan palaeolake basin revealed, for the first time, Middle Palaeolithic occupations. Recovery of Middle Palaeolithic assemblages corresponds with recent environmental and geoarchaeological studies that indicate at least three lacustrine wet phases in MIS 5 [23]. The main diagnostic lithic technology observed is the preferential Levallois reduction method, which is also present at the Jubbah palaeolake during MIS 5 (JQ-1, JSM-1 and JKF-1 sites: [21], [22]) and at the Jebel Faya rock shelter at the transition between MIS 6–5e (Assemblage C: [6]). This technology is absent in MIS 3 in southwest Yemen (SD1, SD2 and AS1 sites: [8], [9]). Earlier dating for preferential Levallois in Arabia, in MIS 7, is possible, but still insufficiently represented owing to small sample size at the Jubbah palaeolake (JQ-1: [22]). Other preferential Levallois methods have been observed in Dhofar, including in the Nubian Complex, dated to at least ca. 106 ka [7], in Hadramawt and the southern fringe of the Rub’ al-Khali, Oman [10], and in central Saudi Arabia at Al-Kharj [75]. Nubian Complex technology has not yet been identified at Mundafan. We associate the Levallois component in Mundafan with the wet pluvials of MIS 5, most probably during the wetter events of MIS 5e (ca. 125 ka), MIS 5c (ca. 100 ka) and MIS 5a (80 ka), when conditions were more favorable for hominin dispersals. The Middle Palaeolithic evidence thus provides empirical support for Rosenberg and colleagues assertion [23] that the dispersal of hominins into the Rub’ al-Khali occurred during ameliorated periods, and perhaps supports their claim for the expansion of Homo sapiens into this marginal environment.
PLoS ONE 8(7): e69665. doi:10.1371/journal.pone.0069665

Middle Palaeolithic and Neolithic Occupations around Mundafan Palaeolake, Saudi Arabia: Implications for Climate Change and Human Dispersals

Rémy Crassard et al.

The Arabian Peninsula is a key region for understanding climate change and human occupation history in a marginal environment. The Mundafan palaeolake is situated in southern Saudi Arabia, in the Rub’ al-Khali (the ‘Empty Quarter’), the world’s largest sand desert. Here we report the first discoveries of Middle Palaeolithic and Neolithic archaeological sites in association with the palaeolake. We associate the human occupations with new geochronological data, and suggest the archaeological sites date to the wet periods of Marine Isotope Stage 5 and the Early Holocene. The archaeological sites indicate that humans repeatedly penetrated the ameliorated environments of the Rub’ al-Khali. The sites probably represent short-term occupations, with the Neolithic sites focused on hunting, as indicated by points and weaponry. Middle Palaeolithic assemblages at Mundafan support a lacustrine adaptive focus in Arabia. Provenancing of obsidian artifacts indicates that Neolithic groups at Mundafan had a wide wandering range, with transport of artifacts from distant sources.

Link

May 21, 2013

Cosmic impact event ~12.8kya caused the Younger Dryas

PNAS doi: 10.1073/pnas.1301760110

Evidence for deposition of 10 million tonnes of impact spherules across four continents 12,800 y ago

James H. Wittke et al.

Airbursts/impacts by a fragmented comet or asteroid have been proposed at the Younger Dryas onset (12.80 ± 0.15 ka) based on identification of an assemblage of impact-related proxies, including microspherules, nanodiamonds, and iridium. Distributed across four continents at the Younger Dryas boundary (YDB), spherule peaks have been independently confirmed in eight studies, but unconfirmed in two others, resulting in continued dispute about their occurrence, distribution, and origin. To further address this dispute and better identify YDB spherules, we present results from one of the largest spherule investigations ever undertaken regarding spherule geochemistry, morphologies, origins, and processes of formation. We investigated 18 sites across North America, Europe, and the Middle East, performing nearly 700 analyses on spherules using energy dispersive X-ray spectroscopy for geochemical analyses and scanning electron microscopy for surface microstructural characterization. Twelve locations rank among the world’s premier end-Pleistocene archaeological sites, where the YDB marks a hiatus in human occupation or major changes in site use. Our results are consistent with melting of sediments to temperatures >2,200 °C by the thermal radiation and air shocks produced by passage of an extraterrestrial object through the atmosphere; they are inconsistent with volcanic, cosmic, anthropogenic, lightning, or authigenic sources. We also produced spherules from wood in the laboratory at >1,730 °C, indicating that impact-related incineration of biomass may have contributed to spherule production. At 12.8 ka, an estimated 10 million tonnes of spherules were distributed across ∼50 million square kilometers, similar to well-known impact strewnfields and consistent with a major cosmic impact event.

Link

May 16, 2013

Toba eruption did not cause volcanic winter in Africa ~75ka

PNAS May 14, 2013 vol. 110 no. 20 8025-8029 doi: 10.1073/pnas.1301474110

Ash from the Toba supereruption in Lake Malawi shows no volcanic winter in East Africa at 75 ka

Christine S. Lane et al.

The most explosive volcanic event of the Quaternary was the eruption of Mt. Toba, Sumatra, 75,000 y ago, which produced voluminous ash deposits found across much of the Indian Ocean, Indian Peninsula, and South China Sea. A major climatic downturn observed within the Greenland ice cores has been attributed to the cooling effects of the ash and aerosols ejected during the eruption of the Youngest Toba Tuff (YTT). These events coincided roughly with a hypothesized human genetic bottleneck, when the number of our species in Africa may have been reduced to near extinction. Some have speculated that the demise of early modern humans at that time was due in part to a dramatic climate shift triggered by the supereruption. Others have argued that environmental conditions would not have been so severe to have such an impact on our ancestors, and furthermore, that modern humans may have already expanded beyond Africa by this time. We report an observation of the YTT in Africa, recovered as a cryptotephra layer in Lake Malawi sediments, >7,000 km west of the source volcano. The YTT isochron provides an accurate and precise age estimate for the Lake Malawi paleoclimate record, which revises the chronology of past climatic events in East Africa. The YTT in Lake Malawi is not accompanied by a major change in sediment composition or evidence for substantial temperature change, implying that the eruption did not significantly impact the climate of East Africa and was not the cause of a human genetic bottleneck at that time.

Link

October 16, 2012

Compasses would have pointed south for 440 years ~41 thousand years ago.

Recent research indicates that when the Campanian Ignimbrite event occurred, the Neandertals were already on the way out. I'd say that the circa 40ka period would make the ideal setting for some good palaeo-fiction. You have volcanic explosions, modern humans replacing Neandertals, magnetic field reversals, and a new set of characters in the mysterious Denisovans. This stuff practically writes itself. On that topic, does anyone have any good prehistoric fiction recommendations?

Earth and Planetary Science Letters Volumes 351–352, 15 October 2012, Pages 54–69

Dynamics of the Laschamp geomagnetic excursion from Black Sea sediments

N.R. Nowaczyk et al.

Investigated sediment cores from the southeastern Black Sea provide a high-resolution record from mid latitudes of the Laschamp geomagnetic polarity excursion. Age constraints are provided by 16 AMS 14C ages, identification of the Campanian Ignimbrite tephra (39.28±0.11 ka), and by detailed tuning of sedimentologic parameters of the Black Sea sediments to the oxygen isotope record from the Greenland NGRIP ice core. According to the derived age model, virtual geomagnetic pole (VGP) positions during the Laschamp excursion persisted in Antarctica for an estimated 440 yr, making the Laschamp excursion a short-lived event with fully reversed polarity directions. The reversed phase, centred at 41.0 ka, is associated with a significant field intensity recovery to 20% of the preceding strong field maximum at ∼50 ka. Recorded field reversals of the Laschamp excursion, lasting only an estimated ∼250 yr, are characterized by low relative paleointensities (5% relative to 50 ka). The central, fully reversed phase of the Laschamp excursion is bracketed by VGP excursions to the Sargasso Sea (∼41.9 ka) and to the Labrador Sea (∼39.6 ka). Paleomagnetic results from the Black Sea are in excellent agreement with VGP data from the French type locality which facilitates the chronological ordering of the non-superposed lavas that crop out at Laschamp–Olby. In addition, VGPs between 34 and 35 ka reach low northerly to equatorial latitudes during a clockwise loop, inferred to be the Mono lake excursion.

Link

September 22, 2012

ESHE 2012 abstracts

Some abstracts of interest from the European Society for the study of Human Evolution 2012 meeting (pdf). To avoid making this too long, I will just post the titles and the most relevant quotes. You can read the abstracts in the linked pdf for authors names and more information.


Neandertal and Denisovan Genomes from the Altai 
Susanna Sawyer  et al.
In 2010 a draft genome sequence was determined from a small finger bone found in Denisova Cave in southern Siberia. Its analysis revealed that it derives from an individual who belonged to a population related to, but distinct from, Neandertals. A molar has also been described from Denisova Cave and has shown to carry an mtDNA genome closely related to that of the finger bone.  We have recently determined the DNA sequence of the Denisova genome to a quality similar to present-day human genomes. We have also retrieved a complete mitochondrial genome and nuclear DNA sequences from an additional molar found in Denisova Cave. Furthermore, we have determined a high-quality nuclear genome from a pedal phalanx found in Denisova Cave in 2010. We show that the pedal phalanx derived from a Neandertal and thus that Neandertals as well as Denisovans have been present in the cave. We will discuss the genetic history of Denisovans as well as Neandertals in light of these new genome sequences. 

The discovery of a Neandertal genome from Denisova cave is certainly interesting. I have previously commented that:
If Vindija and Denisova, two caves less than 5,000km apart were home to people more divergent from each other than any two humans are today, it's strange to think that only "modern humans" inhabited Africa at the same time.
Now, it appears that Neandertals and Denisovans were present (when?) not only 5Mm apart, but literally on the same spot. Much later, during the Neolithic we see very differentiated humans co-existing in Europe. And, we get archaic hominins in Africa long after the appearance of anatomically modern humans there. I think the evidence is looking good for my hypothesis that regional human populations have recently gotten more similar over time through extensive admixture between divergent hominin groups, rather than that they became more dissimilar over time  through tree-like divergence.

On the same topic, here is more evidence for Neandertal presence in the Altai:

A Neanderthal mandible fragment from Chagyrskaya Cave (Altai Mountains, Russian Federation)
Both the mandible and the dentition preserve numerous derived Neanderthal traits: among else a posteriorly placed mandibular foramen, an oblique mylohyoid line, an asymmetrical P4 and continuous mid-trigonid crests on the M1 and M2. ... Ongoing ancient DNA analyses of the hominin remains from Chagyrskaya cave and absolute dates for the site will hopefully help to clarify the origin of the Altai Neanderthals, and their relationship with the Denisovans.

An hypothesis for the phylogenetic position of Homo floresiensis
Our cladistic analysis places H. floresiensis unequivocally as part of a clade with H. habilis
Who are you calling ”modern”? An assessment of the dental morphology and metrics of Homo sapiens

Although dental reduction has long been cited as a derived feature of H. sapiens, our data indicate this claim may be no longer tenable ... the single metrical assessment that groups all H. sapiens (early, Upper Paleolithic and recent) apart from other taxa is the ratio between mandibular:maxillary crown areas.  the results of our study are important for assessing recent claims of great antiquity for H. sapiens outside of Africa
Neanderthal in Malthusian demographic trap

It can be hypothesized that the demography of the Neanderthal metapopulation, living under conditions where extreme environmental instability with short periods was the norm, was primarily stagnant,
with frequent bottlenecks and episodes of decline.
 A New Framework for the Upper Paleolithic of Eastern Europe

The results of field and laboratory research during the past decade require a new classificatory framework for the Upper Paleolithic in Eastern Europe. It is now apparent that people making artifacts assigned to the Ahmarian industry occupied both the southern and northern slopes of the Caucasus Mountains (i.e., Ortvale Klde, Layer 4d; Mezmaiskaya Cave, Layer 1C). Their sites probably indicate a separate movement of anatomically modern humans (AMH) from the Near East directly into Eastern Europe, establishing an independent line of development during the earlier Upper Paleolithic that parallels the Proto-Aurignacian and Aurignacian sequence in Western and Central Europe. this East European industry is most fully represented at the Kostenki-Borshchevo sites on the Don River before 40,000 cal BP (e.g., Kostenki 14, Layer IVb). It is followed by a closely related industry, also characterized by bladelet production, that is dated to the interval between 40,000 and 30,000 cal BP in Crimea and the East European Plain. The proposed new framework reflects recognition of these distinctive East European entities and of two environmental events that had significant impacts on human settlement in Eastern Europe: (1) the Campanian Ignimbrite (CI) volcanic eruption (40,000 cal BP); and (2) the Last Glacial Maximum (LGM) ( 25,000 cal BP). It has been suggested that the early Upper Paleolithic (EUP) industry present in Eastern Europe before 40,000 cal BP should be labeled an eastern variant of the contemporaneous Proto-Aurignacian of Mediterranean Europe. However, given the separate movement of people from the Near East via the Caucasus Mountains, and independent development of the East European EUP, this industry is more appropriately termed “Proto-Gravettian.” The younger bladelet industry, which includes assemblages at Buran-Kaya III (Layer 6-1), Mira (Layer II/2), Kostenki 8 (Layer II), and probably Shlyakh (Layers 4C, 6), may be termed “Early Gravettian” to distinguish it from the classic Gravettian industry that dates to less than 30,000 cal BP (e.g., Avdeevo, Zaraisk).The upper temporal boundary of the Proto-Gravettian corresponds to the CI eruption (40,000 cal BP), while the classic Gravettian of the East European Plain appears to have been effectively terminated by the LGM ( 25,000 cal BP). Several sites that date to the 40,000–30,000 cal BP interval (e.g., Kostenki 1, Layer III) contain elements that suggest a connection with the Aurignacian technocomplex of Western-Central Europe. These assemblages may be placed into the category of “Eastern Aurignacian,” which reflects differences in content with the West and Central European sites. The apparent spread of this industry into Eastern Europe from Central Europe may be related to the impact of the CI eruption on portions of the East European Plain. 
 Conflicting dates for the Late Aterian
First at the huge Ifri n’Ammar sites, TL dates have indicated 80,000 years for the Late Middle Palaeolithic/Aterian levels. Our new C14 dates yield 35,000 BP for exactly the same levels. At the “grotte des Contrebandiers”, formerly dated at 28,000 BP by Debenath and his team, is now dated at 100,000 years by new TL dates. As starting points, this kind of methodological contradiction should be confronted, understood and resolved.
 The Rio Secco Cave in the North Adriatic Region, Italy. A new context for investigating the Neanderthal demise and the settllement of Anatomically Modern Humans
A sequence of several thin layers dated to 46.0–42.1ky Cal BP represents the final Mousterian.
The Dhofar Nubian Tradition: an enduring Middle Stone Age technocomplex in southern Arabia

Between 2010 and 2012, the Dhofar Archaeological Project has located and mapped 260 Nubian Complex occurrences across the Nejd Plateau of southern Oman. Diagnostic Nubian artifacts werefound cemented in fluvial sediments at the site of Aybut Al Auwal in Dhofar, with two OSL dates around 106 ka BP; hence, roughly contemporaneous with the African Nubian Complex (Rose et al. 2011). Many of these lithic assemblages, such as that from Aybut al Auwal, are technologically homologous to the Late Nubian Industry found in northeast Africa, sensu stricto, while others may represent local facies of the greater “Afro-Arabian Nubian Technocomplex.” This presentation describes the various reduction strategies encountered at a sample of Nubian Complex sites from Oman, explores inter-assemblage variability, and begins to articulate technological units within the “Dhofar Nubian Tradition.” To achieve this aim, we have developed an analytical scheme with which to describe technological variability among Nubian Levallois reduction strategies in both Africa and Arabia. Our analysis indicates at least two distinct Nubian industries. The first, which we refer to as the “Classic Dhofar Nubian,” is virtually identical to Late Nubian Industry from the Lower Nile Valley and Red Sea Hills in Egypt. Thee subsequent group of assemblages in Dhofar, called the “Mudayyan,” exhibits a technological shift toward diminutive Nubian Levallois cores and that, recurrent bidirectional cores with opposed, faceted striking platforms. We interpret this evidence to indicate an enduring, local Nubian tradition in Dhofar that is ultimately rooted in the African Nubian Complex. 
From Late Mousterian to Evolved Aurignacian: New evidence for the Middle-to-Upper Paleolithic transition in Mediterranean Spain
Combined, the evidence from CA and FDM indicates that, in chronostratigraphic terms, the Middle-to-Upper Paleolithic transition in Murcia consists of the replacement of a Late Mousterian by an Evolved Aurignacian and occurred some time during the 38th millennium cal BP




August 20, 2012

Human population size over time (Theunert et al. 2012)

The authors of the current paper estimate a 13,601 ancestral and 22,915 current size for Yoruba, with an expansion beginning at 20.15ky. For Europeans, a more complex model provides a better fit, with an ancestral size of 10,065 going through a bottleneck to 3,300 at 39.5ky and recovering at 32.5ky to a current size of 18,300.

I note that the 2.5x10^-8 mutation rate was used to derive these estimates. The model used in this paper infers population size changes on the basis of both allele frequency and linkage disequilibrium, so it is not clear what the use of the slower directly measured mutation rate which led to the re-dating of the human-chimp divergence will have.

Since the direct rate is about half of the widely used 2.5x10^-8, it might be the case that the European bottleneck will approach the ~70ky turning point which is associated with the Toba eruption and the drying up of the Sahara-Arabia belt. That sounds like a most opportune time for a population living in Eurasia to go through a 3-fold reduction in size! Moreover, the Yoruba expansion may be re-dated to around ~40ky, which would correspond to the Middle to Lower Stone Age transition in Africa. Again, an excellent time for a population whose size was pretty constant to experience growth!

Indeed, according to a recent paper on climate history, the middle regions of Africa were more shielded from climate change than North Africa/Levant, so less extreme variations in size in tropical Africa vs. a drastic bottleneck in North Africa/Levant where the ancestors of Europeans were at the time, makes excellent sense to me.

In another recent paper that used a 2.35x10^-8 mutation rate (Lukic et al. 2012), the founding of the Eurasian population was estimated at 52ky. But, if the direct rate is used, this estimate will probably coincide with the crucial ~100ky mark that coincides with the first appearance of anatomically modern human in the Levant at Skhul/Qafzeh, associated with a Mousterian lithic technology, as well as the appearance of the Nubian Complex in South Arabia. So, there is no need to speculate about the early Out-of-Africa-that-failed with respect to these processes and postulate unwarranted coastal migrations.

A new calibration of the mtDNA phylogeny is probably also needed. Time-dependent evolution in mtDNA when the new human-chimp calibration is used will result in a new saturation curve, where mtDNA evolution will occur at recent times with something close to the genealogical rate, and at long (pre-AMH) intervals at the long-term evolutionary rate conditioned on the Pan-Homo divergence. Someone ought to "do the dates" again, but I don't think it's inconceivable that the L3 clade corresponding to the Out-of-Africa event will be updated from 70ky to something like100ky as well, with the origins of the Eurasian M and N lineages approaching 70ky themselves. So, the puzzle of L3 may in fact be resolved: it may be of ~100ky African origin, with later Eurasian clades N and M appearing at the same time as the ~70ky bottleneck.

It seems to me that the directly measured rate of 1-1.3x10^-8 is a better fit than the widely used one of 2.5x10^-8. Many of the papers currently appearing still use the old rate, so their conclusions need to be updated. 

It seems that the major Out-of-Africa event happened pre-100ky, the Eurasian bottleneck occurred at ~70ky and coincided with well-known adverse geo-climatic developments; some of the survivors went north Out-of-Arabia out this time, started interbreeding with Neandertals, and finally the MP/UP transition occurred post-50ka, probably first in the Levant, and followed very quickly in Russia, Central Europe, and the Mediterranean.

Mol Biol Evol (2012) doi: 10.1093/molbev/mss175

Inferring the History of Population Size Change from Genome-Wide SNP Data

Christoph Theunert, Kun Tang, Michael Lachmann, Sile Hu and Mark Stoneking

Dense, genome-wide single-nucleotide polymorphism (SNP) data can be used to reconstruct the demographic history of human populations. However, demographic inferences from such data are complicated by recombination and ascertainment bias. We introduce two new statistics, allele frequency-identity by descent (AF-IBD) and allele frequency-identity by state (AF-IBS), that make use of linkage disequilibrium information and show defined relationships to the time of coalescence. These statistics, when conditioned on the derived allele frequency, are able to infer complex population size changes. Moreover, the AF-IBS statistic, which is based on genome-wide SNP data, is robust to varying ascertainment conditions. We constructed an efficient approximate Bayesian computation (ABC) pipeline based on AF-IBD and AF-IBS that can accurately estimate demographic parameters, even for fairly complex models. Finally, we applied this ABC approach to genome-wide SNP data and inferred the demographic histories of two human populations, Yoruba and French. Our results suggest a rather stable ancestral population size with a mild recent expansion for Yoruba, whereas the French seemingly experienced a long-lasting severe bottleneck followed by a drastic population growth. This approach should prove useful for new insights into populations, especially those with complex demographic histories.

Link

August 06, 2012

Climate history of Africa (150-30ka)




This is an extremely important article for anyone wishing to understand the climate history of Africa during the time of the emergence of modern humans. I'm no climatologist, so the arguments about glaciation cycles, currents, monsoons, orbital cycles, etc. go mostly over my head. But, I did manage to glean some useful information from the article:

  1.  Climate change in Africa was asynchronous; where one region may have experienced a wet phase, another one may have experienced a dry one. Moreover, its variations did not correspond perfectly with Marine Isotope Stages and glaciation cycles.
  2. The impact of wet and dry phases may be different by region. A wet phase in the Sahara means more vegetation and game, and more people; by contrast, a wet phase in a tropical region means more and denser rainforest, and more hardship.
  3. The middle regions of Africa were more shielded from climate change than either north or south Africa: human occupation appears more even; however, West and East Africa seem to have been following opposite trajectories: "Relative site abundances in tropical Africa increase during one period of aridity (~115-90 ka), and in East Africa decline during the comparable interval of humidity (~110-95 ka)."
A quote from the paper:
Hominin dispersals to Eurasia via northern Africa have also been linked to humid intervals (Osbourne et al., 2008; Drake et al., 2011). From ~30-75 ka, North Africa experienced arid climate regimes. The Sahara expanded 65-50 ka and the demographic data imply abandonment of the interior of North Africa during this time (Fig. 15), suggesting that dispersals from North Africa occurred prior to 75 ka. This finding is at odds with hypotheses that posit a dispersal timing of ca. 60 ka (Mellars, 2006), or a dispersal origin in the South African Howiesons Poort industry at 65-60 ka (Marean, 2010), although a ca. 65-60 ka dispersal could well have occurred from East Africa over the Bab el-Mendeb, as humid conditions dominated the latter region between 80 and 65 ka. The timing of the humid intervals in North Africa (~135-115 ka and ~105-75 ka) corresponds with those in the Levant (54a) (Vaks et al., 2007), providing multiple opportunities for one or more earlier hominin dispersals out of Africa via the Sahara, or an early exodus from East Africa to Arabia over the Bab el Mendeb (e.g., Rose et al., 2011). This pattern does not rule out possible migrations from this region during either the earlier or the later interval through the Nile Valley. However, during the ~105-75 ka humid interval in North Africa, East Africa (where the sources of the Nile occur) was largely under an arid climate regime, except for a narrow window ~80 ka when both northern and eastern Africa were experiencing humid climates (Fig. 15), placing a more restricted temporal window on dispersal via the Nile Valley. We note that although only one out of Africa event is recorded in the modern human genome (e.g., Prugnolle et al., 2005), this fact is not inconsistent with earlier multiple migration and extinction events using any of these routes, with only a single lineage surviving to the present.
It will probably take me a while to digest the information in this paper, but I'm definitely glad that someone thought to write it. For the time being I will try to sanity-check my own two deserts theory:

  • The 135-115ka humid interval in the Sahara and the Levant could explain the origin and growth of a population that would spill over to Asia at this time. Jebel Faya may date to this period.
  • ~115ka the onset of dryness would have been detrimental to populations in the Sahara-Arabia belt. It is at this time that site abundances increase in tropical Africa which is also becoming drier, and hence more conducive to human occupation (less dense rainforest); we can perhaps infer that the deepest human lineages got isolated from the rest of mankind as they entered tropical Africa, and even reached Southern Africa which was humid at this time.
  • Post 105ka we see another wet phase in North Africa/Levant, which would again spill over to Asia; the Nubian Complex appears at around this time in Arabia. There are uncertainties of dating about the Skhul/Qafzeh modern humans, and they may date from this time, or the previous wet period (135-115ka).
  • At the 70ka mark where something big may have happened, North Africa/Levant go to a dry period; this is perhaps a good time to see survival of a few lineages (mtDNA L3 and Y-chromosome BT and CT) and another exodus of modern humans from this area. An exodus from East Africa at this time would not make much sense because humans would go from a humid region to a dry one; it would be an awful time for Africans to be headed to Asia.


J Hum Evol. 2012 May;62(5):563-92. Epub 2012 Apr 17.

The environmental context for the origins of modern human diversity: a synthesis of regional variability in African climate 150,000-30,000 years ago.

Blome MW, Cohen AS, Tryon CA, Brooks AS, Russell J.

Abstract We synthesize African paleoclimate from 150 to 30 ka (thousand years ago) using 85 diverse datasets at a regional scale, testing for coherence with North Atlantic glacial/interglacial phases and northern and southern hemisphere insolation cycles. Two major determinants of circum-African climate variability over this time period are supported by principal components analysis: North Atlantic sea surface temperature (SST) variations and local insolation maxima. North Atlantic SSTs correlated with the variability found in most circum-African SST records, whereas the variability of the majority of terrestrial temperature and precipitation records is explained by local insolation maxima, particularly at times when solar radiation was intense and highly variable (e.g., 150-75 ka). We demonstrate that climates varied with latitude, such that periods of relatively increased aridity or humidity were asynchronous across the northern, eastern, tropical and southern portions of Africa. Comparisons of the archaeological, fossil, or genetic records with generalized patterns of environmental change based solely on northern hemisphere glacial/interglacial cycles are therefore imprecise. We compare our refined climatic framework to a database of 64 radiometrically-dated paleoanthropological sites to test hypotheses of demographic response to climatic change among African hominin populations during the 150-30 ka interval. We argue that at a continental scale, population and climate changes were asynchronous and likely occurred under different regimes of climate forcing, creating alternating opportunities for migration into adjacent regions. Our results suggest little relation between large scale demographic and climate change in southern Africa during this time span, but strongly support the hypothesis of hominin occupation of the Sahara during discrete humid intervals ~135-115 ka and 105-75 ka. Hominin populations in equatorial and eastern Africa may have been buffered from the extremes of climate change by locally steep altitudinal and rainfall gradients and the complex and variable effects of increased aridity on human habitat suitability in the tropics. Our data are consistent with hominin migrations out of Africa through varying exit points from ~140-80 ka.

Link

July 24, 2012

Volcanic ash didn't kill Neandertals, modern humans did

Related story by Michael Balter:
The team collected samples containing CI cryptotephra from four central European caves where stone tools and other artifacts typical of Neandertals and modern humans have been found. They also gathered the particles from a modern human site in Libya and from marshland and marine sites in Greece and the Aegean Sea. The results, the team argues in a paper published online this week in the Proceedings of the National Academy of Sciences, are incompatible with the hypothesis that the CI was responsible for Neandertal extinction, at least in central Europe. The CI cryptotephra lie above, and so postdate, the transition from Neandertal to modern human stone tool types at all four central European sites, indicating that modern humans had replaced Neandertals before the catastrophic events of 40,000 years ago.
It's a little strange that modern humans arrive in Europe by the late 40,000s cal BP, replace the Neandertals, and shortly -in geological terms- thereafter, a massive volcano goes off on them. Perhaps, a little nemesis?

PNAS doi: 10.1073/pnas.1204579109

Volcanic ash layers illuminate the resilience of Neanderthals and early modern humans to natural hazards

John Lowe et al.

Marked changes in human dispersal and development during the Middle to Upper Paleolithic transition have been attributed to massive volcanic eruption and/or severe climatic deterioration. We test this concept using records of volcanic ash layers of the Campanian Ignimbrite eruption dated to ca. 40,000 y ago (40 ka B.P.). The distribution of the Campanian Ignimbrite has been enhanced by the discovery of cryptotephra deposits (volcanic ash layers that are not visible to the naked eye) in archaeological cave sequences. They enable us to synchronize archaeological and paleoclimatic records through the period of transition from Neanderthal to the earliest anatomically modern human populations in Europe. Our results confirm that the combined effects of a major volcanic eruption and severe climatic cooling failed to have lasting impacts on Neanderthals or early modern humans in Europe. We infer that modern humans proved a greater competitive threat to indigenous populations than natural disasters.

Link

July 10, 2012

Extraterrestrial impact caused Younger Dryas 12,900 years ago

PNAS doi: 10.1073/pnas.1204453109

Very high-temperature impact melt products as evidence for cosmic airbursts and impacts 12,900 years ago

Ted E. Bunch et al.

It has been proposed that fragments of an asteroid or comet impacted Earth, deposited silica-and iron-rich microspherules and other proxies across several continents, and triggered the Younger Dryas cooling episode 12,900 years ago. Although many independent groups have confirmed the impact evidence, the hypothesis remains controversial because some groups have failed to do so. We examined sediment sequences from 18 dated Younger Dryas boundary (YDB) sites across three continents (North America, Europe, and Asia), spanning 12,000 km around nearly one-third of the planet. All sites display abundant microspherules in the YDB with none or few above and below. In addition, three sites (Abu Hureyra, Syria; Melrose, Pennsylvania; and Blackville, South Carolina) display vesicular, high-temperature, siliceous scoria-like objects, or SLOs, that match the spherules geochemically. We compared YDB objects with melt products from a known cosmic impact (Meteor Crater, Arizona) and from the 1945 Trinity nuclear airburst in Socorro, New Mexico, and found that all of these high-energy events produced material that is geochemically and morphologically comparable, including: (i) high-temperature, rapidly quenched microspherules and SLOs; (ii) corundum, mullite, and suessite (Fe3Si), a rare meteoritic mineral that forms under high temperatures; (iii) melted SiO2 glass, or lechatelierite, with flow textures (or schlieren) that form at > 2,200 °C; and (iv) particles with features indicative of high-energy interparticle collisions. These results are inconsistent with anthropogenic, volcanic, authigenic, and cosmic materials, yet consistent with cosmic ejecta, supporting the hypothesis of extraterrestrial airbursts/impacts 12,900 years ago. The wide geographic distribution of SLOs is consistent with multiple impactors.

Link

May 29, 2012

RIP matrilocal egalitarian early European farmers

It seems that Marija Gimbutas' feminist Old Europe fantasy is collapsing like a house of cards.

Michael Balter covers this in Science:
The results of the study, published online today in the Proceedings of the National Academy of Sciences, suggest that men who were buried with adzes—thought to be an indication of higher social status—were more likely to have grown up on loess soils than men who were buried without adzes.
...
A similarly striking pattern was seen when the team looked at the female skeletons, which made up 153 of the total 311 individuals analyzed. The variation in strontium ratios for females was significantly greater than for males, suggesting that a greater number of females than males had grown up in non-fertile areas.
...
The team came to two main conclusions: First, some males had greater access to fertile soils than others, probably because they were the sons of farmers who had inherited access to the best land. And second, LBK societies were "patrilocal," meaning that males tended to stay put in one place while females moved in from other areas to mate with them.
From the press release:

Professor Bentley said: "Our results, along with archaeobotanical studies that indicate the earliest farmers of Neolithic Germany had a system of land tenure, suggest that the origins of differential access to land can be traced back to an early part of the Neolithic era, rather than only to later prehistory when inequality and intergenerational wealth transfers are more clearly evidenced in burials and material culture. 
"It seems the Neolithic era introduced heritable property (land and livestock) into Europe and that wealth inequality got underway when this happened. After that, of course, there was no looking back: through the Bronze Age, Iron Age and Industrial era wealth inequality increased but the 'seeds' of inequality were sown way back in the Neolithic."
PNAS doi: 10.1073/pnas.1113710109

Community differentiation and kinship among Europe’s first farmers

R. Alexander Bentley et al.

Community differentiation is a fundamental topic of the social sciences, and its prehistoric origins in Europe are typically assumed to lie among the complex, densely populated societies that developed millennia after their Neolithic predecessors. Here we present the earliest, statistically significant evidence for such differentiation among the first farmers of Neolithic Europe. By using strontium isotopic data from more than 300 early Neolithic human skeletons, we find significantly less variance in geographic signatures among males than we find among females, and less variance among burials with ground stone adzes than burials without such adzes. From this, in context with other available evidence, we infer differential land use in early Neolithic central Europe within a patrilocal kinship system.

Link

May 08, 2012

Late glacial recolonization of Europe from Near Eastern refugia

A couple of quick comments on this important new paper:

  • It is important to confirm the hypotheses put forward with ancient DNA data. For example, haplogroup V is said to be traced to Paleolithic SW Europe, and yet it is lacking in ancient DNA data. Looking at Jean Manco's ancient Eurasian DNA compendium, I only find a very late Neolithic hunter-gatherer sample from Pitted Ware in Sweden (2,800-2,000BC); if J/T subclades had entered Europe prior to the Neolithic, their almost complete absence in ancient DNA data is puzzling.
  • Both this and the recent "Copernican" paper provide age estimates for the same nodes of the tree using the mutation rate of Soares et al. (2009). The estimaets of Pala et al. (2012) appear to be older by several thousand years than those of Behar et al. (2012) for different nodes. I don't know whether this is due to a different methodology or different dataset, but, in any case, it is a warning to avoid very close correlations between archaeological-geological events and age estimates.
UPDATE: A press release on the article.

The American Journal of Human Genetics, Volume 90, Issue 5, 915-924, 4 May 2012 doi:10.1016/j.ajhg.2012.04.003

Mitochondrial DNA Signals of Late Glacial Recolonization of Europe from Near Eastern Refugia

Maria Pala et al.

Human populations, along with those of many other species, are thought to have contracted into a number of refuge areas at the height of the last Ice Age. European populations are believed to be, to a large extent, the descendants of the inhabitants of these refugia, and some extant mtDNA lineages can be traced to refugia in Franco-Cantabria (haplogroups H1, H3, V, and U5b1), the Italian Peninsula (U5b3), and the East European Plain (U4 and U5a). Parts of the Near East, such as the Levant, were also continuously inhabited throughout the Last Glacial Maximum, but unlike western and eastern Europe, no archaeological or genetic evidence for Late Glacial expansions into Europe from the Near East has hitherto been discovered. Here we report, on the basis of an enlarged whole-genome mitochondrial database, that a substantial, perhaps predominant, signal from mitochondrial haplogroups J and T, previously thought to have spread primarily from the Near East into Europe with the Neolithic population, may in fact reflect dispersals during the Late Glacial period, ∼19–12 thousand years (ka) ago.

Link

April 05, 2012

Meltwater Pulse 1A (MWP-1A)

Nature 483, 559–564 (29 March 2012) doi:10.1038/nature10902

Ice-sheet collapse and sea-level rise at the Bølling warming 14,600 years ago

Pierre Deschamps et al.

Past sea-level records provide invaluable information about the response of ice sheets to climate forcing. Some such records suggest that the last deglaciation was punctuated by a dramatic period of sea-level rise, of about 20 metres, in less than 500 years. Controversy about the amplitude and timing of this meltwater pulse (MWP-1A) has, however, led to uncertainty about the source of the melt water and its temporal and causal relationships with the abrupt climate changes of the deglaciation. Here we show that MWP-1A started no earlier than 14,650 years ago and ended before 14,310 years ago, making it coeval with the Bølling warming. Our results, based on corals drilled offshore from Tahiti during Integrated Ocean Drilling Project Expedition 310, reveal that the increase in sea level at Tahiti was between 12 and 22 metres, with a most probable value between 14 and 18 metres, establishing a significant meltwater contribution from the Southern Hemisphere. This implies that the rate of eustatic sea-level rise exceeded 40 millimetres per year during MWP-1A.

Link

November 29, 2011

Aurignacian in Greece >40 thousand years ago

Related:
Antiquity Volume: 85 Number: 330 Page: 1131–1150

Franchthi Cave revisited: the age of the Aurignacian in south-eastern Europe

K. Douka1 et al.

The Aurignacian, traditionally regarded as marking the beginnings of Sapiens in Europe, is notoriously hard to date, being almost out of reach of radiocarbon. Here the authors return to the stratified sequence in the Franchthi Cave, chronicle its lithic and shell ornament industries and, by dating humanly-modified material, show that Franchthi was occupied either side of the Campagnian Ignimbrite super-eruption around 40000 years ago. Along with other results, this means that groups of Early Upper Palaeolithic people were active outside the Danube corridor and Western Europe, and probably in contact with each other over long distances.Along with other results, this means that groups of Early Upper Palaeolithic people were active outside the Danube corridor and Western Europe, and probably in contact with each other over long distances.

Link