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August 31, 2013

Poverty: a peculiar type of stress that dramatically reduces cognitive function

An average of 13 IQ points. It's not being poor what causes it but the stress of scarcity of resources, which simply copes the brain.

I reproduce the press release in full (with just some emphasis of my own) because of it's great interest:

Poor concentration: Poverty reduces brainpower needed for navigating other areas of life

Poverty and all its related concerns require so much mental energy that the poor have less remaining brainpower to devote to other areas of life, according to research based at Princeton University. As a result, people of limited means are more likely to make mistakes and bad decisions that may be amplified by — and perpetuate — their financial woes.

Published in the journal Science, the study presents a unique perspective regarding the causes of persistent poverty. The researchers suggest that being poor may keep a person from concentrating on the very avenues that would lead them out of poverty. A person's cognitive function is diminished by the constant and all-consuming effort of coping with the immediate effects of having little money, such as scrounging to pay bills and cut costs. Thusly, a person is left with fewer "mental resources" to focus on complicated, indirectly related matters such as education, job training and even managing their time.
In a series of experiments, the researchers found that pressing financial concerns had an immediate impact on the ability of low-income individuals to perform on common cognitive and logic tests. On average, a person preoccupied with money problems exhibited a drop in cognitive function similar to a 13-point dip in IQ, or the loss of an entire night's sleep.



Sugarcane Farmer
Research based at Princeton University found that poverty and all its related concerns require so much mental energy that the poor have less remaining brainpower to devote to other areas of life.

Experiments showed that the impact of financial concerns on the cognitive function of low-income individuals was similar to a 13-point dip in IQ, or the loss of an entire night's sleep. To gauge the influence of poverty in natural contexts, the researchers tested 464 sugarcane farmers in India who rely on the annual harvest for at least 60 percent of their income. Each farmer performed better on common fluid-intelligence and cognition tests post-harvest compared to pre-harvest.
But when their concerns were benign, low-income individuals performed competently, at a similar level to people who were well off, said corresponding author Jiaying Zhao, who conducted the study as a doctoral student in the lab of co-author Eldar Shafir, Princeton's William Stewart Tod Professor of Psychology and Public Affairs. Zhao and Shafir worked with Anandi Mani, an associate professor of economics at the University of Warwick in Britain, and Sendhil Mullainathan, a Harvard University economics professor.

"These pressures create a salient concern in the mind and draw mental resources to the problem itself. That means we are unable to focus on other things in life that need our attention," said Zhao, who is now an assistant professor of psychology at the University of British Columbia.

"Previous views of poverty have blamed poverty on personal failings, or an environment that is not conducive to success," she said. "We're arguing that the lack of financial resources itself can lead to impaired cognitive function. The very condition of not having enough can actually be a cause of poverty."
The mental tax that poverty can put on the brain is distinct from stress, Shafir explained. Stress is a person's response to various outside pressures that — according to studies of arousal and performance — can actually enhance a person's functioning, he said. In the Science study, Shafir and his colleagues instead describe an immediate rather than chronic preoccupation with limited resources that can be a detriment to unrelated yet still important tasks.

"Stress itself doesn't predict that people can't perform well — they may do better up to a point," Shafir said. "A person in poverty might be at the high part of the performance curve when it comes to a specific task and, in fact, we show that they do well on the problem at hand. But they don't have leftover bandwidth to devote to other tasks. The poor are often highly effective at focusing on and dealing with pressing problems. It's the other tasks where they perform poorly."

The fallout of neglecting other areas of life may loom larger for a person just scraping by, Shafir said. Late fees tacked on to a forgotten rent payment, a job lost because of poor time-management — these make a tight money situation worse. And as people get poorer, they tend to make difficult and often costly decisions that further perpetuate their hardship, Shafir said. He and Mullainathan were co-authors on a 2012 Science paper that reported a higher likelihood of poor people to engage in behaviors that reinforce the conditions of poverty, such as excessive borrowing.

"They can make the same mistakes, but the outcomes of errors are more dear," Shafir said. "So, if you live in poverty, you're more error prone and errors cost you more dearly — it's hard to find a way out."

The first set of experiments took place in a New Jersey mall between 2010 and 2011 with roughly 400 subjects chosen at random. Their median annual income was around $70,000 and the lowest income was around $20,000. The researchers created scenarios wherein subjects had to ponder how they would solve financial problems, for example, whether they would handle a sudden car repair by paying in full, borrowing money or putting the repairs off.

Participants were assigned either an "easy" or "hard" scenario in which the cost was low or high — such as $150 or $1,500 for the car repair. While participants pondered these scenarios, they performed common fluid-intelligence and cognition tests.

Subjects were divided into a "poor" group and a "rich" group based on their income. The study showed that when the scenarios were easy — the financial problems not too severe — the poor and rich performed equally well on the cognitive tests. But when they thought about the hard scenarios, people at the lower end of the income scale performed significantly worse on both cognitive tests, while the rich participants were unfazed.

To better gauge the influence of poverty in natural contexts, between 2010 and 2011 the researchers also tested 464 sugarcane farmers in India who rely on the annual harvest for at least 60 percent of their income. Because sugarcane harvests occur once a year, these are farmers who find themselves rich after harvest and poor before it. Each farmer was given the same tests before and after the harvest, and performed better on both tests post-harvest compared to pre-harvest.

The cognitive effect of poverty the researchers found relates to the more general influence of "scarcity" on cognition, which is the larger focus of Shafir's research group. Scarcity in this case relates to any deficit — be it in money, time, social ties or even calories — that people experience in trying to meet their needs. Scarcity consumes "mental bandwidth" that would otherwise go to other concerns in life, Zhao said.

"These findings fit in with our story of how scarcity captures attention. It consumes your mental bandwidth," Zhao said. "Just asking a poor person to think about hypothetical financial problems reduces mental bandwidth. This is an acute, immediate impact, and has implications for scarcity of resources of any kind."

"We documented similar effects among people who are not otherwise poor, but on whom we imposed scarce resources," Shafir added. "It’s not about being a poor person — it's about living in poverty."

Many types of scarcity are temporary and often discretionary, said Shafir, who is co-author with Mullainathan of the book, "Scarcity: Why Having Too Little Means So Much," to be published in September. For instance, a person pressed for time can reschedule appointments, cancel something or even decide to take on less.

"When you're poor you can't say, 'I've had enough, I'm not going to be poor anymore.' Or, 'Forget it, I just won't give my kids dinner, or pay rent this month.' Poverty imposes a much stronger load that's not optional and in very many cases is long lasting," Shafir said. "It's not a choice you're making — you're just reduced to few options. This is not something you see with many other types of scarcity."

The researchers suggest that services for the poor should accommodate the dominance that poverty has on a person's time and thinking. Such steps would include simpler aid forms and more guidance in receiving assistance, or training and educational programs structured to be more forgiving of unexpected absences, so that a person who has stumbled can more easily try again.

"You want to design a context that is more scarcity proof," said Shafir, noting that better-off people have access to regular support in their daily lives, be it a computer reminder, a personal assistant, a housecleaner or a babysitter.
"There's very little you can do with time to get more money, but a lot you can do with money to get more time," Shafir said. "The poor, who our research suggests are bound to make more mistakes and pay more dearly for errors, inhabit contexts often not designed to help."



Ref. Anandi Madi et al., Poverty Impedes Cognitive Function. Science 2013. Pay per viewLINK [doi:10.1126/science.1238041]

I must say that I find extremely sad that a study so important for people of scarce resources is pay per view.

August 28, 2013

Echoes from the past (August-28-2013)

Oh, yeah, I admit it: I have been procrastinating a lot. Result: an extremely long "to do" list. Naturally, I can't make up for all the past laziness, so here goes a synthesis of what would otherwise be left unattended, take your time, please. 

Middle Paleolithic:

Atapuerca holds "uninterrupted" sequence of European humans since 1.2 million years ago. Soon-to-be-published theory of continuity from H. erectus to Neanderthals in the Castilian site → Paleorama[es], EFE Futuro[es].

More Neanderthal evidence for symbolism found in Fumane cave (Veneto, Italy): polished and ochre-painted shells (pictured) → PLoS ONE (open access), El neandertal tonto ¡qué timo![es].



Upper Paleolithic:

Epigravettian burial, dated to ~14,000 BP, found in Cuges-les-Pins (Provence). The Epigravettian (and not the more widespread Magdalenian) culture of this site indicates a direct link to Italy → INRAP[fr], La Provence[fr], Los Andes[es].

Oldest modern human remain of Galicia found at Valdavara cave (Becerreá, Lugo province). The milk tooth is 17,000 years old, 7000 years older than any other such finding in the NW Iberian country → Pileta[es], IPHES[cat].


Epipaleolithic:

Thousands of engravings, dated to c. 6000 years ago, found in Coahuila (Mexico) → RTVE[es].



"World's oldest calendar" found in Scotland → BBC.

Female burial found at Poças de São Bento (Sado basin, Portugal) → Paleorama[es].


Neolithic:

First farmers were inbred (at least in Southern Jordan) → Science Magazine.

Qatar Neolithic dig shows the peninsula was in contact with early Sumerian civilization (Eridu or Ubaid period, the first empire ever) → The Archaeology News Network.

Manure was already used by Europe's first farmers → Science.


Chalcolithic:

Haryana (India) town is oldest large IVC settlement → Business Standard.

East China engravings show first Oriental writing (~5000 years' old, just slightly younger aged as Sumerian cuneiform writing but much more recent than the controversial Tărtăria tablets of Bulgaria) → The Guardian, English People.

North American natives caused lead pollution in Lake Michigan (oldest recorded) → PPV paper (ER&T)University of Pittsburg.

Perdigões enclosure and collective burial was pilgrimage center. Antonio Valera (often so scholarly cryptic at his blog) loosens up when interviewed by a Portuguese publication, giving meaning to the archeology he's working with → Super Interesante[por].


Bronze Age:

Cypriot harbor city dug: Hala Sultan Tekke, near modern Larnaka, had 25-50 Ha. and was active between the 16th and 12th centuries BCE → The Archaeology News Network.

Also from Cyprus: large settlement dug out near Nicosia (Cyprus), dated to 2000-1500 BCE → The Archaeology News Network.


Human evolution:

Modern human shoulder much more efficient than chimpanzees' at throwing... but also than H. erectus' → BBC.

Neanderthals did speak (of course) → Science Daily, open access paper (Frontiers in Psychology).
Note: their unfounded insistence on most unlikely H. heidelbergensis shared origins of Neanderthals and us casts some doubt on elements of their reasoning however.

Genetics:

Record ancient DNA: ~700,000 years' old horse sequenced → Nature Communications (PPV).


Experimental archaeology:

How to carve your own stone tools and weapons out of modern materials: very interesting videos (in English) at Paleorama[es] (scroll down). 


More tomorrow (nope my "to do" list is not at all finished with this entry).

Central European farmers, but also Danish "hunter-gatherers" had domestic pigs

It's often difficult to discern in the archaeological record wild boar remains from those of domestic pigs. Luckily archaeogenetics can solve the problem, sometimes producing striking results.

Ben Krause-Kyora et al., Use of domesticated pigs by Mesolithic hunter-gatherers in northwestern Europe. Nature Communications 2013. Open accessLINK [doi:10.1038/ncomms3348]
Abstract

Mesolithic populations throughout Europe used diverse resource exploitation strategies that focused heavily on collecting and hunting wild prey. Between 5500 and 4200 cal BC, agriculturalists migrated into northwestern Europe bringing a suite of Neolithic technologies including domesticated animals. Here we investigate to what extent Mesolithic Ertebølle communities in northern Germany had access to domestic pigs, possibly through contact with neighbouring Neolithic agricultural groups. We employ a multidisciplinary approach, applying sequencing of ancient mitochondrial and nuclear DNA (coat colour-coding gene MC1R) as well as traditional and geometric morphometric (molar size and shape) analyses in Sus specimens from 17 Neolithic and Ertebølle sites. Our data from 63 ancient pig specimens show that Ertebølle hunter-gatherers acquired domestic pigs of varying size and coat colour that had both Near Eastern and European mitochondrial DNA ancestry. Our results also reveal that domestic pigs were present in the region ~500 years earlier than previously demonstrated.

The most striking result is surely not the demonstration of pigs being in Central Europe a few centuries than previously confirmed but that Ertebølle hunter-gatherers of Denmark had them as well, quite radically casting doubt on their status as hunter-gatherers and placing them fully in the Neolithic context, even still rather marginal and peripheral. 


Figure 1: Map depicting the location of the archaeological Sus samples from which mtDNA haplotypes were obtained.
Samples were recovered from Neolithic LBK, post-LBK and Mesolithic Ertebølle sites dated between 5500 and 4000 cal BC. Each symbol corresponds to a single sample (triangle, square and circle). Domestic (triangle) and wild (square) pigs discussed in the text are labelled; circles represent Sus specimens of unknown domestication status. The red colour indicates the European haplotypes C and A, and yellow the Near Eastern haplotypes Y1 and Y2.

"Modern human behavior" is out, generic human potential is in

There is a hypothetical model in Prehistory on something vague and ethereal which has been called "Modern human behavior" (MHB). It's not about nuclear weapons, Internet addiction nor commuting to work; it's not either about the printing machine, the Industrial Revolution and the ideals of Human Rights; it's not even about farming, living in cities and through sailing the seas... it's about something extremely vague and ill-defined but which, by definition would set apart "modern humans" (H. sapiens) from "archaic humans" (other Homo species, particularly Neanderthals).

While it is almost intangible and every day more dubious, a large number of prehistorians, some as notorious as Mellars, Stringer or Bar-Yosef, strikingly influenced by religious ideas setting an arbitrarily absolutist line between "humans" (i.e. Homo sapiens) and the rest (including other humans), have insisted for decades on the validity of such notion. Now three researchers challenge the model radically:

Christopher J. H. James, Julien Riel-Salvatore & Benjamin R. Collins, Why We Need an Alternative Approach to the Study of Modern Human Behaviour. Canadian Journal of Archaeology Volume 37, Issue 1 (2013). Pay per viewLINK


They essentially argue that: that the model (of which there are several, often contradictory variants) is extremely useless and confusing, that there are "archaic humans" with many or even all traits of MHB and there are "modern humans" without many or even most of them.

They tentatively argue for a throughout revision of the model but then they seem to lean rather for the whole abandonment of the idea suggesting instead a mosaic and punctuated evolution pattern that is socio-cultural rather than merely genetic or essentialist:

(...) the rapidly accumulating evidence for a mosaic pattern of behavioural change (...) and the evidence of behavioural advances appearing and rapidly disappearing in the MSA, make the harsh dichotomy model untenable. What it does suggest is a punctuated or saltation model that led to widespread adoption of more complex behavioural patterns once the demographic circumstances were appropriate (...).

Somehow this made me recall one of my all-time favorite bands: Suicidal Tendencies and their 1990 hit "Disco's out, murder's in" (surely not apt for pop, techno and folk music lovers):

August 11, 2013

Belarusian uniparental ancestry

A new study on Belarusian haploid genetics provides some interesting insights for the wider European and West Eurasian picture.

Alena Kushniarevich et al., Uniparental Genetic Heritage of Belarusians: Encounter of Rare Middle Eastern Matrilineages with a Central European Mitochondrial DNA Pool. PLoS ONE 2013. Open accessLINK [doi:10.1371/journal.pone.0066499]

Abstract

Ethnic Belarusians make up more than 80% of the nine and half million people inhabiting the Republic of Belarus. Belarusians together with Ukrainians and Russians represent the East Slavic linguistic group, largest both in numbers and territory, inhabiting East Europe alongside Baltic-, Finno-Permic- and Turkic-speaking people. Till date, only a limited number of low resolution genetic studies have been performed on this population. Therefore, with the phylogeographic analysis of 565 Y-chromosomes and 267 mitochondrial DNAs from six well covered geographic sub-regions of Belarus we strove to complement the existing genetic profile of eastern Europeans. Our results reveal that around 80% of the paternal Belarusian gene pool is composed of R1a, I2a and N1c Y-chromosome haplogroups – a profile which is very similar to the two other eastern European populations – Ukrainians and Russians. The maternal Belarusian gene pool encompasses a full range of West Eurasian haplogroups and agrees well with the genetic structure of central-east European populations. Our data attest that latitudinal gradients characterize the variation of the uniparentally transmitted gene pools of modern Belarusians. In particular, the Y-chromosome reflects movements of people in central-east Europe, starting probably as early as the beginning of the Holocene. Furthermore, the matrilineal legacy of Belarusians retains two rare mitochondrial DNA haplogroups, N1a3 and N3, whose phylogeographies were explored in detail after de novo sequencing of 20 and 13 complete mitogenomes, respectively, from all over Eurasia. Our phylogeographic analyses reveal that two mitochondrial DNA lineages, N3 and N1a3, both of Middle Eastern origin, might mark distinct events of matrilineal gene flow to Europe: during the mid-Holocene period and around the Pleistocene-Holocene transition, respectively.

Mitochondrial DNA

Belarusians have typical Central-Eastern European mtDNA pools, with some 37% H (of which: c. 11% H1 and 15% unclassified H*), c. 12% U5 (roughly half for each major subclade: U5a and U5b) and a diversity of other lineages:

Figure 2. Phylogeny of mtDNA haplogroups and their relative frequencies in Belarusians.
The tree is rooted relative to the RSRS according to [51]. Belarusian sub-populations are designated as BeE – East, BeWP – West Polesie, BeEP – East Polesie, BeN – North, BeC – Centre, BeW – West. Sample sizes and absolute frequencies are also given.

From the paper:
Frequencies of Belarusian mtDNA haplogroups do not differ considerably from other eastern European and Balkan populations, at least when major clades such as H1, H2, V, U5a and U5b, K, T and J are considered (Table S3). However, populations from the easternmost fringe of the eastern European region, the Volga-Uralic, have a decreased share of overall H mtDNAs and a noticeably increased frequency of haplogroup U4 as well as M-lineages compared to Belarusians (Table S3).

Of interest is the rare lineage N3, also found in around the Eastern Mediterranean (from Albania to Egypt) and in Iran, where it probably originated (highest diversity), spreading to Europe possibly in the Neolithic.

Another rare lineage, N1a3, is most frequent among Peninsular Arabs (but with low HVS-I diversity), being also found in the Eastern Mediterranean (from Sicily to Palestine) and the Caucasus. It is very rare in Central and Eastern Europe, excepted Mordvins (but again low diversity). It's precise origins remain unclear (either West Asia or the European SE, included Italy, where it seems quite diverse). Based on their own age estimates, the authors suggest a rather old diversification of this lineage still in Paleolithic times.


Y chromosome DNA

Belarusian paternal ancestry is dominated by R1a (51%), I2a1 ("I2a": 17%) and N1c (10%). Other notable lineages are R1b (6%) and I1 (5%). All them are within expectations.

Figure 6. Phylogeny of NRY haplogroups and their relative frequencies in Belarusians.
Haplogroup-defining biallelic markers are in parentheses. Belarusian sub-populations are designated as BeN – North, BeC – Centre, BeE – East, BeW – West, BeWP – West Polesie, BeEP – East Polesie. Sample sizes and absolute frequencies are also given.

I2a1 ("I2a" in the paper) is more common towards the South or SE. Instead N1c shows the opposite distribution, being more common in the North and West. This distribution is concordant with the wider East European picture.

Both lineages show star-like STR structures. Based on them, the authors suggest that, only for Belarusian lineages, N1c (fig. 7)may have spread from the Baltic area (Lithuania, Latvia NW Belarus), while I2a1 (fig. 8) would have spread from the Balcans and maybe Belarus itself. We should not read beyond Belarus here because of the sampling bias of the study (notably regarding N1c, with very few Uralic samples).

August 1, 2013

Pre-pottery Neolithic in North-Central Arabia

And yet another Cressard study, this time on the Neolithic of North-Central Arabia Peninsula.

Rémy Cressard et al., Beyond the Levant: First Evidence of a Pre-Pottery Neolithic Incursion into the Nefud Desert, Saudi Arabia. PLoS ONE 2013. Open access → LINK [doi:10.1371/journal.pone.0068061]

Abstract

Pre-Pottery Neolithic assemblages are best known from the fertile areas of the Mediterranean Levant. The archaeological site of Jebel Qattar 101 (JQ-101), at Jubbah in the southern part of the Nefud Desert of northern Saudi Arabia, contains a large collection of stone tools, adjacent to an Early Holocene palaeolake. The stone tool assemblage contains lithic types, including El-Khiam and Helwan projectile points, which are similar to those recorded in Pre-Pottery Neolithic A and Pre-Pottery Neolithic B assemblages in the Fertile Crescent. Jebel Qattar lies ~500 kilometres outside the previously identified geographic range of Pre-Pottery Neolithic cultures. Technological analysis of the typologically diagnostic Jebel Qattar 101 projectile points indicates a unique strategy to manufacture the final forms, thereby raising the possibility of either direct migration of Levantine groups or the acculturation of mobile communities in Arabia. The discovery of the Early Holocene site of Jebel Qattar suggests that our view of the geographic distribution and character of Pre-Pottery Neolithic cultures may be in need of revision.


Figure 1. Map of the Neolithic Near East with the different geo-cultural zones of the core area (or Fertile Crescent), in green; after Aurenche and Kozlowski [82].
The JQ-101 site is located in the southern part of the Nefud Desert in Saudi Arabia.

Critically the Jebel Qattar site includes characteristic fossils: the El Khiam and Heluwan points, that link it clearly to the Southern Levant (i.e. Palestine and Jordan). This may relate this colonization with proto-Semitic or very early Semitic peoples, which are often suspected to be related to these cultures. In particular I wonder if these peoples may have been already carrying the seed of the Southern Semitic languages which once extended through Southern Arabia and parts of The Horn of Africa (now restricted mostly to Eritrea and Ethiopia, although still surviving among the Mehri and Socotran).

South Arabian paleolake Mundafan was inhabited in the Middle Paleolithic and later in the Neolithic

Another study also by Cressard researches two greatly different periods of occupation of what was once a lake in Southern Saudi Arabia, not far from Yemen.

Rémy Cressard et al., Middle Palaeolithic and Neolithic Occupations around Mundafan Palaeolake, Saudi Arabia: Implications for Climate Change and Human Dispersals. PLoS ONE 2013. Open accessLINK [doi:10.1371/journal.pone.0069665]

Abstract

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.

Figure 5. General views of the Mundafan palaeolake.
Again the content is rich in details of great interest for the archaeologist and prehistorian but surely a bit harder to digest for the casual aficionado.

Of interest anyhow is that no Nubian Complex affinities have been observed in the Middle Paleolithic tools and cores, suggesting again that the colonization of Arabia and Palestine from Africa was multifaceted, with different and sometimes ill-defined cultural sources.

As for the Neolithic a problem is that in this and other sites, all findings are located on the surface, being therefore impossible to date stratigraphically. The kind of tanged arrowheads suggests, by comparison with other sites, that these findings belong to the oldest Neolithic phase, c. 8000-6000 calBP. There are no findings that could be attributed to later periods, probably because the area became just too dry. Interestingly:
The Mundafan Neolithic sites do not appear to be sedentary locations on the basis of the absence of architectural features, grindstones, domesticated faunal remains, and relatively low artifact densities. The prevalence of projectiles and other weaponry is probable evidence of hunting activities. Mundafan would have been a favorable setting for short-term hunting along the lakeshore. The presence of rare obsidian artifacts demonstrates Mundafan’s participation in long-distance mobility systems that included relations with the obsidian-rich mountainous zones of Yemen, some 400–500 km away from the site.

While the term "Neolithic" is used in the paper, the kind of economy that the people living there had seems to have been hunter-gatherer.

Nubian Complex in Central Arabia

The Nubian Complex MSA techno-culture arrived to Central Arabia, just south of Riyadh seemingly via the South

Rémy Cressard & Yamandú H. Hilbert, A Nubian Complex Site from Central Arabia: Implications for Levallois Taxonomy and Human Dispersals during the Upper Pleistocene. PLoS ONE 2013. Open accessLINK [doi:10.1371/journal.pone.0069221]

Abstract

Archaeological survey undertaken in central Saudi Arabia has revealed 29 surface sites attributed to the Arabian Middle Paleolithic based on the presence of Levallois blank production methods. Technological analyses on cores retrieved from Al-Kharj 22 have revealed specific reduction modalities used to produce flakes with predetermined shapes. The identified modalities, which are anchored within the greater Levallois concept of core convexity preparation and exploitation, correspond with those utilized during the Middle Stone Age Nubian Complex of northeast Africa and southern Arabia. The discovery of Nubian technology at the Al-Kharj 22 site represents the first appearance of this blank production method in central Arabia. Here we demonstrate how a rigorous use of technological and taxonomic analysis may enable intra-regional comparisons across the Arabian Peninsula. The discovery of Al-Kharj 22 increases the complexity of the Arabian Middle Paleolithic archaeological record and suggests new dynamics of population movements between the southern and central regions of the Peninsula. This study also addresses the dichotomy within Nubian core typology (Types 1 and 2), which was originally defined for African assemblages.


Figure 3. Levallois methods schemata: figuration of product and core shapes for each method.
A: Preferential Levallois flake production with centripetal preparation; B: Preferential Levallois point production with unidirectional convergent preparation; C: Nubian Levallois type 1 with distal divergent preparation; D: Nubian Levallois type 2 with double lateral preparation; E: Nubian Levallois type 1/2 with mixed type 1 and type 2 preparation.
Figure 10. Schematic representation depicting the three main dorsal preparation types, preparation type 1, 2 and 1/2, and the proposed reduction succession discussed in the text.
In order to facilitate comprehension cores, end-products and preparation by-products have been color-coded; blue equals type 1 preparation, green type 2 and yellow type 1/2.

Many more images of interest for experts or qualified amateurs are available in this high quality study. For the less specialized reader it is probably more interesting to ponder the overall extension of the Nubian Complex:

Figure 11. Distribution of main sites with Nubian cores in Eastern Africa and Arabia.
Illustrated cores do not represent actual size. 1. Al-Kharj 22 (this study); 2. Aybut Al Auwal [12]; 3. Shabwa [30]; 4. Hadramawt [5], [6], [27]; 5. Aduma [112]; 6. Gademotta [113]; 7. Asfet [114]; 8. Nazlet Khater 1 [115]; 9. Abydos [66].

The authors argue that Southern and Central Arabia are the Easternmost reaches of this complex, however we cannot forget that the recent discovery of Indian sites with a complex industry, dated to c. 96 Ka ago, of Nubian, Aterian and other MSA affinities challenges this notion.

See also in this blog: