Anthropology.net

Back in August of this year, two words I frequently encountered when trying to visit sites of interest in Andalucía, southern Spain, were“Cerrado” (closed) and “No”, which as a tourist you take in your stride, leg it to the nearest hostelry and reconsider the rest of the day from the perspective of its slightly less interesting alternatives. As an eminent archaeologist working on what is potentially one of the more important sites in Spanish archaeology, with the prospect of confirming the latest known Neanderthals to have lived anywhere in the world, you might hope for more positive words from those tasked with permitting your work to go ahead unhindered. But as we see from the sorry tale unfolding below, this is not always the case, especially where the cave of La Carihuela is concerned.

Martin Cagliani at Mundo Neandertal points us towards this story, in which Spanish archaeologists are complaining that the local Junta (legislative assembly) of Andalucía will not allow the re-excavation of the Mousterian layers in the cave which it closed in 1996, (although work seems to have been conducted at least as late as 1998 by Carrión, linked PDF, Fig.2) where it is claimed there are Neanderthal remains dating to around 21,500 years bp, located within the cave of La Carihuela, about 45 km from Granada. If confirmed, this would make these Neanderthals far younger even than those whose artefactual traces have been found at Gorham’s Cave on Gibraltar dating to around 24,500 bp, at the same time perhaps taking the species’ existence right up to the Last Glacial Maximum.

The news article referred to is in Spanish, and is reported at Público.es, from which I’ll roughly translate some of the more pertinent points, while there’s also a freely accessible paper (PDF) on the subject of pollen sequences in the cave, as well as a description of its layout, the stratigraphic sequences within the galleries,  published in 2006, to which I’ll briefly refer throughout.

The report begins by describing how the cave might be the site of the very last Neanderthals tthat once walked this planet, because following the discovery of a male (Neanderthal) skull back in the 1950s, in the vicinity of Mousterian stone tools, it was realised shortly thereafter that according to pollen analyses, the layer from which the fossil had been retrieved might date to as late as 21,500 years bp.

Excavations began in earnest during the late 1970s, and by the early 1990s, a team of 30 researchers were working there, putting it on a par with Atapuerca, near Burgos in the north,  for the amount of effort invested in the site. But in 1996, following what is described as an arbitrary decision by local authorities, this work came to a sudden halt, and despite repeated requests from the archaeological community to reopen the cave, the Junta has remained obstinately silent on the case, allegedly not even picking up the phone to engage in the debate, according to D. Gerardo Vega Toscano. Profesor Titular, Dpto. de Prehistoria. UCM, Madrid.

He remarks that the scientists in this case are effectively at the mercy of the politicians, who basically don’t give two hoots whether the cave is the last refuge of the Neanderthals, or simply a hole in the ground.

One wonders from reading this whether the Junta is a fit and appropriate body to hold sway over such affairs, and moreover where the Spanish Ministry of Culture stands in this – surely it should be they who decide the scientific importance and appropriate funding levels required by such sites, and I find it hard to believe that no-one from the Ministry has seen fit to intervene.

Vega Toscano is for his part unconvinced of the very late date of 21,500 bp proposed for the remains, which he cites as absurd, opining instead that a date of 28,000 years bp is a more realistic proposition – it should be noted here that the estimate based on the pollen samples uses 28,440 bp and 21,430 bp as its parameters, with the real date presumably falling somewhere in between the two. The oldest known actual remains of Neanderthals are from Zafarraya, occupied between 31,000-27,000 bp, and the remains at La Carihuela should provide secure dates assuming that the specimens are in good enough condition.

Gorham’s Cave on Gibraltar is also known as a late Neanderthal refuge, with a most recent date of 24,500 bp ascribed there to Mousterian artefacts, while in Portugal at Lagar Velho, what appear to be the remains of a hybrid Neanderthal child are also put at 24,500 bp, so there seems no reason why a similar date shouldn’t apply at La Carihuela, and maybe 21,500 years bp, or a millennium or two beforehand, in the overall context isn’t completely out of the question. The fact that Mousterian technologies appear to have continued to be employed right up to the very end is interesting in itself, suggesting a lack of contact between archaic and anatomically modern populations – whether further investigations within Carihuela will reveal late-surviving Neanderthals were using bone or antler implements in addition to their own Mousterian tool-kits remains to be seen, but seems doubtful.

Contrary to the opinions of Vega Toscano, there is however support for the much later Neanderthal survival dates, as the article goes on to report the opinions of José Carrión, Professor of Botany at the University of Murcia, who remarks that 21,000 years bp marks the start of the Glacial Maximum, when temperatures plunged ever deeper for the following 3,000 years, a situation he believes could have tipped Neanderthals over the edge, coinciding with the extinction of fauna such as the mastodon and sabre-toothed tiger. (Although Neanderthals had previously survived through at least 2 previous ice ages, they had done so in the absence of competition from AMH, and as far as I’m aware, no major faunal extinctions had taken place in the earlier glaciations either, or at least not to the extent that Neanderthal prey animals disappeared from the menu).

Carrión further makes the point that apart from pollen dating, the bones from La Carihuela can be dated, and so might yet reveal themselves to be younger than the Gorham’s Cave presence – whether the fossil skull mentioned earlier has been dated isn’t stated here, and whether it continues to languish unexamined in a Granada museum, isn’t clear. Other researchers have dismissed the idea that climate alone could have accounted for the demise of the Neanderthals, preferring instead to cite a multitude of inter-related factors.

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As this paper is freely accessible for the next 7 days, I’m posting it here in the hope that as many readers as possible will have time to read it through. Molly Fox et al turn their thoughts to the question of why women are able to live for many years after they able to conceive offspring, a phenomenon seemingly at odds with the idea that members of a species tend to die off once their reproductive days are over.

The ‘Grandmother Hypothesis’ is described and expanded upon thus in the linked paper:

With menopause occurring around age 50, women survive several decades longer than their gametes (Dorland et al. 1998; Hawkes 2003). Why should women have such conservative life histories that they save up enough energy for 25 years of reproductive retirement? Human females represent a particular conundrum in evolutionary studies: after menopause they are unable to reproduce and have no obvious way to increase their genetic contribution to future generations. As this is the basis for natural selection, many researchers have sought to explain how post-menopausal longevity is adaptive in women.

Among evolutionary biologists, the ‘grandmother hypothesis’ is the most widely recognized explanation for human female post-reproductive longevity. It suggests that vigorous, skilled, elderly women are able to contribute to their grandchildren’s survivorship through nutritional provisioning (Hawkes et al. 1998; Hawkes 2003). According to Hamilton’s relatedness coefficients (Hamilton 1966), grandmothers share a quarter of their DNA with grandchildren, and so a woman can increase her genetic contribution to subsequent generations by keeping her grandchildren alive and healthy. Supporters of this model often refer to the Hadza, a modern foraging society in Tanzania, where grandmothers are more effective than children at extracting tubers from the dry ground. While a mother is breastfeeding an infant, and thus unable to forage enough to provide for weaned children, the grandmother provides food for the older siblings (Hawkes 2003; Hawkes & Jones 2005).

The authors further suggest that this may be a behavioural and survival trait that can trace its roots back to the early Pleistocene, 1.7m-1.9m years bp (described in the paper as the Plio-Pleistocence boundary, recently re-dated to 2.6m years bp), when global cooling caused the expansion of African tuber-friendly grasslands, prompting ancient hominids to include a great many more tubers in their diet. From these origins, where grandmothers are suggested to have been important contributors of nutrition to two generations of descendants, researchers such as Soffer and Adovasio have taken the theory further, suggesting that grandmothers contributed a much greater role in child-rearing than simply providing nutritional foodstuffs.

The interesting aspect of this paper is how the authors suggest simply having a grandmother isn’t equally beneficial to grandchildren of either gender, with clear differences suggesting that in some instances having a maternal grandmother can be better for boys than a paternal grandmother, whilst a grand-daughter with a maternal grandmother appears to benefit most of all, as indicated here:

Tests of the grandmother hypothesis have been carried out on modern and historical populations. Most of the data correlate grandchild survivorship with grandmother survival and/or proximity, and it is often reported that only maternal grandmothers (MGMs) are found to have a positive effect on grandchild survivorship (Sear et al. 2002; Voland & Beise 2002). Studies that have not distinguished between MGMs and paternal grandmothers (PGMs) have found no correlation between grandmother’s presence and grandchild survivorship (Hill & Hurtado 1991; Lahdenperä et al. 2004). To date, only two previous studies known to the authors have distinguished between boys and girls when investigating the effect of both grandmothers.

A study of a Japanese population found that the presence of a PGM had a negative effect on boys and a positive effect on girls, while the presence of an MGM had a positive effect on children of both sexes, especially on boys (Jamison et al. 2002). They point to cultural features of the society as a possible mechanism for these findings. A study of an Ethiopian population reported the sex-specific information, but it was not analysed in the paper (Gibson & Mace 2005). More tests of the grandmother hypothesis are summarized in Sear & Mace (2007).

The authors continue by proposing the following:

The grandmother hypothesis is based on the fact that women are genetically related to their grandchildren, and we should not overlook the nature of that genetic relatedness. Grandsons and granddaughters differ in the proportion of their X-chromosomes shared with MGMs and PGMs (figure 1). According to our proposed X-linked grandmother hypothesis, if grandmothers invest in grandchildren because of their genetic relatedness with them, then their adaptive incentive to invest may vary in a way that mirrors this variation in genetic relatedness. As a consequence, grandmothers’ differential investment in grandchildren could cause differential survivorship of those grandchildren…

…Although the X-chromosome contains only about 4.4 per cent of our DNA, with its estimated 1529 genes, it contains perhaps approximately 8 per cent of all human genes (Pennisi 2003; NIH 2007; Parang et al. 2008; NCBI 2009a). The dramatic differences in X-relatedness between grandmothers and grandchildren confound the Hamiltonian concept that grandchildren are 25 per cent genetically related to each grandparent. If approximately 92 per cent of our genes are autosomes, then a grandmother shares one-quarter of that, or approximately 23 per cent of her total genes with a grandchild, plus X-relatedness.¹

If a grandmother shares no X-chromosome with a grandchild, then their overall genetic relatedness is approximately 23 per cent, and if they share an entire X-chromosome, then it would be approximately 31 per cent. Therefore, MGMs and grandchildren are likely to share 25 per cent of their genomes, while PGM and granddaughter may share a total of approximately 31 per cent of their genes, with a likelihood of 27 per cent inheritance, while a PGM and grandson may share only approximately 23 per cent.

We can only wonder whether these conclusions were borne out in ancient communities and whether it was realised that there was closer bonding and greater survival amongst children with certain alloparental configurations, or whether child-care was undertaken on a more ad hoc basis, whereby other surrogate mothers who were still of reproductive age were also co-opted into rearing off-spring when the need arose. Moreover, infant mortality was probably high and seemingly arbitrary, especially where actions of predators, illness and infections were concerned, in which case the grandmother effect would have been diminished, except in those cases where an older person such as a grandmother would have had greater experience in recognising symptoms and knowing of potential remedies, something which presumably could also have applied also to grandfathers.

I’m not sure at what age humans living in the early and later stages of the Pleistocene would have become grandparents, but my guess would be quite young, possibly by age 30-35, though whether females would also have become unable to conceive by that age I don’t know; but it seems there could have been some overlap, during which time a grandmother could herself have still given birth to children, unless a menopausal clock kicked in soon after their own off-spring had given birth, which seems unlikely. If we still assume an age of 50 for menopause however, by the time she reached 50, a Pleistocene woman could easily find herself in the role of great-grandmother, though whether humans in significant numbers reached that ripe old age back then, again seems unlikely.

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Today marks the half-way point between the most recent edition of Four Stone Hearth and the next, so here’s a quick recap on the 78th edition, as hosted by Paddy K – if by some chance you haven’t been able to read the various entries, please be sure to do so, as there is a very good range of posts covering stuff like the contested origins of Neanderthals in Europe, who as we learn in a presentation from TED probably had fair skins, and on to thick-skinned Creationists who appear not only to have entirely missed the gist of the Ardipithecus implications, but as far as I can tell, apparently show not the slightest interest in the other animals and plant-life, or the landscapes they inhabited 4.4 million years ago, let alone how the sites under investigation came into existence and were preserved in the first place.

One destination almost certainly not on the must-see wish-lists of said Creationists would likely be the seedier side of the British Museum’s less known rooms, where a goodly collection of controversial art and artefacts have accumulated over the years, including an intriguing 11,000 year-old carving in calcite of a couple locked in embrace, from the desert of Judaea, as I recall. Zahi Hawass is heard darkly muttering beneath the brim of his slightly odd hat, whilst elsewhere we see a vision of the future that was old hat before we even got there. There’s plenty more in this issue to make it worth setting aside about an hour to read the lot, so many thanks to Paddy K for continuing what has been a very good series of 4SH blog carnivals, despite the hazardous nature of his cycling activities around the streets of Stockholm.

The next edition, the 79th no less, will be held here at Anthropology.net on Wednesday November 4th – I think my email address for submissions should be somewhere onsite, or if in doubt, maybe get them to me via Martin R; details here at Four Stone Hearth.

There’s been some coverage of a recent announcement by Svante Pääbo of the Max Planck Institute, who opines that Neanderthals and anatomically modern humans had sexual encounters as they co-habited in Upper Palaeolithic Eurasia from around 42,000 bp to 24,500 bp. The main article is over at the London Times, from which this is an excerpt:

Paabo recently told a conference at the Cold Spring Harbor Laboratory near New York that he was now sure the two species had had sex — but a question remained about how “productive” it had been.  “What I’m really interested in is, did we have children back then and did those children contribute to our variation today?” he said.

“I’m sure that they had sex, but did it give offspring that contributed to us? We will be able to answer quite rigorously with the new [Neanderthal genome] sequence.”  Such an answer might ease the controversy over recent contradictory discoveries regarding Neanderthals. Some fossils seem to have both modern human and Neanderthal features, suggesting that the two species interbred. Yet DNA scans have shown that Neanderthal genes were very different from those of modern man.

Pääbo is reported to be at the point of publishing his analysis of the Neanderthal genome, and it seems clear that he has gleaned something from the data that has prompted this latest assertion; previous research has been interpreted as indicating that if the two species did interbreed it was at a very low level, apparently evidenced by the almost complete lack of a Neanderthal presence in our own genome today.

Gene Expression comments thus:

The way Paabo is couching it, what he has found then seems likely to be evidence that humans who had just expanded Out of Africa contributed to the genomes of Neandertals. In other words, modern human introgression into Neandertals. Of course if the gene flow was from modern human to Neandertals exclusively, then it would be an evolutionary dead end since that lineage went extinct.

In any case, for several decades some fossil-based paleoanthropologists have been claiming that there are “intermediate” individuals in the record which indicate modern human-Neandertal hybridization. Most prominently Erik Trinkaus. If Paabo’s finding becomes more solid, then it seems time to update the probabilities on these sorts of claims based purely on morphology.

The story is taken up at Ad Hominin, where the following opinion is expressed:

Today, most researchers acknowledge that some sexual encounters could have occurred between Neandertals and modern humans. The more interesting question is how common were these encounters and did they leave their mark on the modern gene pool. Undoubtedly, modern humans and Neandertals would have recognised each other as fellow humans but this does not mean that they would have acted humanely to each another.

Countless social and psychological studies have shown humans to have a very strong “us versus them” mentality, that no doubt also existed in our ancestors. It is unlikely that modern humans and Neandertals had an easy relationship. Most sexual encounters that took place between the two were likely opportunistic and probably involved enslavement and rape.

Of course we have absolutely no evidence regarding the circumstances under which these liaisons may have taken place, and I imagine the last sentence of the quote above is obliquely referring to the way in which the indigenous Indian populations of the Americas were almost wiped from the face of the Earth by the tide of white Europeans, who staged one of the most brutal and violent land-grabs in recorded history, as they claimed other peoples’ territories for their own, killing thousands in the process.

However, Upper Palaeolithic Europe was a very different place to the Americas of a few centuries ago, with no centralised governments, mobilised armies, or even slavery, as suggested above. I’m not even sure what the duties of a putative slave in the UP would actually be, or how such a state of affairs could even be enforced. The sheer numbers of humans involved in the theft of native peoples’ lands far eclipsed the populations of Ice Age Europe, so although there might have been competition for land and resources, it would have been on a far smaller scale than in modern times.

Moreover, the technological and cultural gap between Neanderthals and incoming moderns was comparatively narrow, as opined by Professor Chris Stringer of the Natural History Museum in London:

“It’s possible that Neanderthals and humans were genetically incompatible, so they could have interbred but their children would have been less fertile,” said Stringer.  This phenomenon is seen in many other species such as when lions breed with tigers and horses breed with zebras.  “I used to believe Neanderthals were primitive,” said Stringer, “but in the last 10,000-15,000 years before they died out, around 30,000 years ago, Neanderthals were giving their dead complex burials and making tools and jewellery, such as pierced beads, like modern humans.”

The popular notion of inter-species sex, as apparent in the previously quoted post, was that brutish Neanderthal men had their wicked way with anatomically modern women by dragging them behind the nearest bush, reinforcing the old stereotype of rapacious cavemen that has so blighted the way in which our archaic ancestors have been viewed for nigh on 150 years.

Because the population of Europe in the Upper Palaeolithic was probably very low in both modern and archaic communities, contact was likely to have been infrequent – indeed it seems quite possible that members of both species lived entire lifetimes without encountering one another – as Neanderthal numbers began to decline, any encounters would become increasingly rare.

And when moderns and Neanderthals did make primary contact, it could have been under any number of circumstances, some of which may have resulted in violence and death, whilst others might have developed into co-operation, friendship, up to and including, romance and kisses. Yet other encounters might have ended in polite ‘nice-to-meet-you’ handshakes, after which the two species quietly got on with minding their own business, without harbouring any particular feelings for or against their new acquaintances.

As a brief aside, I can’t help but speculate that it might have been easier for Neanderthal women to give birth to inter-species offspring than their AMH counterparts – bearing in mind that Neanderthal babies were more robust, the shape and size of their skulls, even when hybridised, would have made it more difficult for AMH mothers to give birth. A Neanderthal woman who had conceived a child fathered by an AMH male would maybe have found it easier to give birth to the hybridised and possibly smaller baby she was carrying – so should we expect to find that hybridised children conceived by Neanderthal women survived in greater numbers than those conceived by AMH mothers? And how would we then consider the evolutionary social factors that led to relationships between the two species that caused AMH men to bond and breed with Neanderthal women? Such a question may be answered in part from this further quote from Ad Hominin:

The recent announcement by Svante Pääbo that he is sure that Neandertals and modern humans had sex is quite a bold pronouncement coming from a scientist. It raises the question of whether this ascertain is based on some hard evidence they found while sequencing the Neandertal genome. It is possible that if there was some Neandertal genes passed on to the first moderns in Europe, they could have got eliminated from the subsequent gene pool as population sizes fluctuated during the more severe climatic episodes. A more likely scenario is that Pääbo’s team found evidence of modern introgression in the Neandertal genome. In all likelihood the incoming modern humans were more numerous than the Neandertals, thereby absorbing the endemic populations through genetic swamping.

This would seem to reinforce the point that any enforced sex is more likely to have been instigated by incoming AMH males on the female Neanderthal population, if we are to take modern history of human conquest and genocide into account and apply the same mind-set to life 30,000 to 40,000 years ago. But the fact that the both modern and archaic populations may have co-existed in Europe for 10,000-15,000 years at least hints that there was no large-scale or organised species cleansing undertaken by AMH, and it’s quite possible that both they and the Neanderthals behaved a great deal better towards each other than has often been the case in our own recorded histories.

It remains to be seen whether this latest research is able to resolve this question of interbreeding, or whether instead tentative clues will emerge that raise more questions than answers.

See also: Video – Svante Pääbo discussing the Neanderthal Genome Project on YouTube.

Science Daily report on a paper published back in June which I appear to have missed, and as it’s freely accessible at PNAS, I’m pleased to be able to link to it here. This is the abstract:

Food storage is a vital component in the economic and social package that comprises the Neolithic, contributing to plant domestication, increasingly sedentary lifestyles, and new social organizations. Recent excavations at Dhra’ near the Dead Sea in Jordan provide strong evidence for sophisticated, purpose-built granaries in a predomestication context
11,300–11,175 cal B.P., which support recent arguments for the deliberate cultivation of wild cereals at this time. Designed with suspended floors for air circulation and protection from rodents, they are located between residential structures that contain plant-processing instillations. The granaries represent a critical evolutionary shift in the relationship between people and plant foods, which precedes the emergence of domestication and large-scale sedentary communities by at least 1,000 years.

One of the authors is Ian Kuijt, who in the current edition of Current Anthropology authored a paper addressing the same subject, namely ‘What Do We Really Know about Food Storage, Surplus, and Feasting in Preagricultural Communities?’ which is behind a subscription paywall, so here’s a brief extract from that:

Food production, social inequality, and storage are interrelated. Despite the general acceptance of this proposition, the roles of storage in emerging social inequality and the development of food production remain poorly understood. Food storage is an awkward topic for researchers as it is not always manifested in ways that are visible or material (see Forbes and Foxhall 1995; Ingold 1983; Stopp 2002; Testart 1982). The reconstruction and definition of what is storage is highly complex, and centers on practices and materials that are not always well preserved.

The identification of storage features, as well as the scale of storage, is undermined by several constraints. First, due to differential preservation, not all food storage can be identified in the archaeological record. While not random, direct preservation of foods through burning or other agents of conservation is inconsistent and unlikely to be representative of the entire range of foods used and stored in a prehistoric economy.

Second, ethnographic accounts of hunter‐gatherers and farmers provide evidence for a wide range of storage practices, some of which occur off site (Stopp 2002). Third, while we can use ethnography to help us understand the past use of architectural features, it is possible that Neolithic storage practices differed from our comparative cases. The archaeological understanding of past storage practices is based largely on preserved features and structures that are empty, and burned paleobotantical remains are rarely recovered. Researchers are often left with no alternative but to develop circumstantial arguments that specific features were used for food storage.

Some researchers (e.g., Hayden 2009, in this issue) argue that the pre‐agricultural Near Eastern Early (14,500–12,800 cal BP) and Late Natufian periods (12,800–11,500 cal BP) were characterized by sufficient food storage and surplus to allow for individuals to gain social power over others. The Natufian periods, which are distinctly different from each other, were characterized by significant seasonal residential sedentism and the extensive harvesting of wild plants (Bar‐Yosef 1998). As with earlier peoples, the Early and Late Natufians were focused on intensive and extensive harvesting of wild cereals (Bar‐Yosef 1998). Natufian people utilized a remarkably wide range of wild plants and animals and probably had a detailed knowledge of the seasonality and availability of these resources. Certainly the increased degree of sedentism in the Early Natufian period suggests that people were able to reduce seasonal food risks to the point where they could live in the same areas for one or more season of the year.

References: Evidence for food storage and predomestication granaries 11,000 years ago in the Jordan Valley, by Ian Kuijt and Bill Finlayson, Published online before print June 22, 2009, doi: 10.1073/pnas.0812764106

Rethinking the Origins of Agriculture: What Do We Really Know about Food Storage, Surplus, and Feasting in Preagricultural Communities? by Ian Kuijt, Current Anthropology Volume 50, Number 5, October 2009 © 2009 by The Wenner‐Gren Foundation for Anthropological Research. All rights reserved. 0011-3204/2009/5005-0009$10.00 DOI: 10.1086/605082

Interesting paper by Dr. Stephen Lycett, of the University of Kent, UK, from which the following extract is taken:

In recent years it has been increasingly recognized that the manufacture of artefacts such as handaxes results from the process of social transmission of knowledge between individuals and across generations [18]–[21]. It is also been increasingly recognized that social transmission may be modeled as a mechanism of inheritance broadly analogous to that of genetic transmission [22]–[27]. This is not to say that these two inheritance mechanisms are identical in all respects.

One obvious difference is that in the case of social transmission the ability to acquire information is not limited solely to copying biological parents; there is also the opportunity to copy more distantly related kin and unrelated individuals. Nevertheless, attention has increasingly been drawn to the fact that the evolution of cultural traditions involves a process of social inheritance, variation in the details of practice, and differential representation of given variants in subsequent generations (i.e. sorting due to various selection processes and cultural drift) (e.g.[28], [29]). One outcome resulting from recognition of this analogous process has been an increase in the application of population genetic and phylogenetic methods drawn from biology in order to understand the evolution of cultural phenomena, including artefacts (e.g.[10], [30]–[43]).

The gist of the author’s proposals is that dispersals from Africa dating from the early Pleistocene are thought to have taken place, but there is very little in the way of preserved human fossil remains to confirm this – instead, he suggests that stone hand-axes can to some extent be relied upon as evidence for these dispersals. For a long-term tradition of making hand-axes to exist, some kind of social transmission is assumed, whereby information about how to source material and modify it in order to make stone hand-axes (and other tools/artefacts) would likely be passed on down the generations through time, (as well as across contemporary communities), and this knowledge would gradually spread over geographical space as migrating populations left their homelands and spread from Africa into Europe, the Near East and much of Asia. And although the raw materials often differed across sites, this factor doesn’t appear to have placed a significant constraint on the spread of  Acheulean lithic industry.

However, it is noted that in some locations such as Elveden in England (+Guba video link) and South Asia, the data don’t always conform to the underlying hypothesis, implying that not all tool-makers far from Africa derived their knowledge from ancestral sources, but in some cases invented ostensibly identical technologies themselves. For example the discovery of Acheulean technologies appearing in India where no contemporary human fossils have been found makes it unclear whether this represents a colonisation event, or if instead there was an independent and localised innovation on the part of the unidentified individuals residing there in the Early Pleistocene.

As with all PLoS ONE papers featured here, readers have free and unlimited access to the text and supplementary materials. Comments and ratings of the numerous papers at the PLoS site are encouraged.

Reference: Lycett SJ (2009) Understanding Ancient Hominin Dispersals Using Artefactual Data: A Phylogeographic Analysis of Acheulean Handaxes. PLoS ONE 4(10): e7404. doi:10.1371/journal.pone.0007404

Two interesting articles that went into my inbox today: Modern man a wimp says anthropologist and Darwin Lives! Modern Humans Are Still Evolving.

Modern man a wimp says anthropologist from Reuters, summarizes Peter McAllister’s book Manthropology: The Science of the Inadequate Modern Male. Using various data from Neanderthals and ancient aboriginal populations, McAllister concludes that modern men are inferior than their predecessor in running, jumping, and even sheer brute. “Any Neanderthal woman could have beaten former bodybuilder and current California governor Arnold Schwarzenegger in an arm wrestle”, McAllister said. John Hawks from John Hawks Weblog has a lot to say about this in his post Is modern man a “wimp”? I think Hawks is spot on with his post.

The Time article, Darwin Lives! Modern Humans Are Still Evolving, is about a study in a contemporary Massachusetts population led by Stephen Stearns and his team of scientists from Yale University. Using correlations between women’s physical characteristics such as height, weight, blood pressure, and cholesterol levels with the numbers of offspring produced, they found that “stout, slightly plump, but not obese” women tend to have more offspring as oppose to women with very low body fat count, as well as women with lower blood pressure and lower cholesterol levels.

Stearns explains that women with very low body fat count, low blood pressure and low cholesterol levels do not ovulate. Ovulation is, of course, when the matured ovarian follicle ruptures and discharge an ovum (or the egg). While human females ovulate about once a month, female chickens ovulate once a day. Of course, we refer to chicken ovum as chicken eggs.

Stearns and his team thinks that the characteristics for producing maximum offspring (stout, slightly plump, higher blood pressure and cholesterol levels) were passed down from mothers to daughters. Separating social and cultural factors using statistical analysis, Stearns and his team were able to conclude that these characteristics were passed down genetically. “Variations in reproductive success still exist among humans, and therefore some traits related to fertility continue to be shaped by natural selection” Stearns says. So women who have more children are more likely to pass down these traits to their offspring.

It explains the notion that modern humans are still evolving because variation in reproductive success means that there are selective pressure that favor certain traits. Interesting to note that while fertility is being shaped by natural selection (as per Stearn and his team’s study), artificial selection is also shaping the width of female pelvis and the average brain size of infants being born. Mothers with a narrow birth canal (smaller pelvis size) puts both her and her infant in jeopardy during childbirth. The infant will be stuck in the birth canal due to restricted space. An infant with a larger than average brain size will also get stuck in the birth canal. Both scenarios will likely kill the infant and mother. However the advent of Caesarean section negates the restriction of a narrow birth canal and allows infant with larger brain size to be born.

So, we can see that modern humans are evolving through variation in reproductive success, female pelvis size and average infant brain size is also evolving through artificial selection though it is too early to say which direction the selection is favoring.

Originally posted on The Prancing Papio.

Brief details of research from Israel which has led authors Mary Stiner et al to ruminate upon the possibility that differing cut-marks from ancient kills may offer insights into how meat-sharing behaviours amongst archaic humans may have evolved through the various stages of the Palaeolithic.

Abstract:

Zooarchaeological research at Qesem Cave, Israel demonstrates that large-game hunting was a regular practice by the late Lower Paleolithic period. The 400- to 200,000-year-old fallow deer assemblages from this cave provide early examples of prime-age-focused ungulate hunting, a human predator–prey relationship that has persisted into recent times. The meat diet at Qesem centered on large game and was supplemented with tortoises.

These hominins hunted cooperatively, and consumption of the highest quality parts of large prey was delayed until the food could be moved to the cave and processed with the aid of blade cutting tools and fire. Delayed consumption of high-quality body parts implies that the meat was shared with other members of the group.

The types of cut marks on upper limb bones indicate simple flesh removal activities only. The Qesem cut marks are both more abundant and more randomly oriented than those observed in Middle and Upper Paleolithic cases in the Levant, suggesting that more (skilled and unskilled) individuals were directly involved in cutting meat from the bones at Qesem Cave. Among recent humans, butchering of large animals normally involves a chain of focused tasks performed by one or just a few persons, and butchering guides many of the formalities of meat distribution and sharing that follow. The results from Qesem Cave raise new hypotheses about possible differences in the mechanics of meat sharing between the late Lower Paleolithic and Middle Paleolithic.

The paper is behind a relatively low pay-wall, (i.e. you’ll still be able to afford food later in the week) but before coughing up the readies, check Physorg.com, who carry a discussion of the research, which includes comment from one of the paper’s authors, Professor Avi Gopher, as shown here:

“The cut marks we are finding are both more abundant and more randomly oriented than those observed in later times, such as the Middle and Upper Paleolithic periods,” says Prof. Avi Gopher of TAU’s Department of Archaeology. “What this could mean is that either one person from the clan butchered the group’s meat in a few episodes over time, or multiple persons hacked away at it in tandem,” he interprets. This finding provides clues as to social organization and structures in these early groups of hunters and gatherers, he adds.

Among human hunters in the past 200,000 years, from southern Africa to upstate New York or sub-arctic Canada, “there are distinctive patterns of how people hunt, who owns the products of the hunt, how carcasses are butchered and shared,” Prof. Gopher says. “The rules of sharing are one of the basic organizing principles of hunter-gatherer cultures. From 200,000 years ago to the present day, the patterns of meat-sharing and butchering run in a long clear line. But in the Qesem Cave, something different was happening. There was a distinct shift about 200,000 years ago, and archaeologists and anthropologists may have to reinterpret hunting and meat-sharing rituals.”

Qesem Cave, the site in question, is described in this abstract from Frumkin et al, 2009:

Résumé / Abstract

The Qesem karst system may serve as an example for aging chamber caves. It includes two caves which have undergone several stages of natural and human-induced deposition, as well as subsidence and collapse. Natural deposits include calcite speleothems, bedrock collapse debris, and clay fill. Karst dissolution and associated sagging and decomposition have operated since the initial cave formation. Inclined sediments are attributed to several processes, mostly dominated by gravitational sagging into underlying dissolution voids, affecting cave deposits and sometimes the host-rock. U-Th dating shows that speleothem deposition has been common during the mid-late Quaternary, but deposition sites shifted according to local conditions. The aging of caves occurs when they become totally filled by sediments and ultimately consumed by surface denudation, as documented in Qesem Cave.

See also: Qesem Cave Project, from where image at top, ‘Fallow deer jaw from Qesem cave’ was sourced.

References:

Cooperative hunting and meat sharing 400–200 kya at Qesem Cave, Israel, 1. Mary C. Stiner, 2. Ran Barkai and 3. Avi Gopher  Published online before print July 28, 2009, doi: 10.1073/pnas.0900564106    PNAS  August 11, 2009   vol. 106  no. 32  13207-13212

Gravitational Deformations and Fillings of Aging Caves : The Example of Qesem Karst System, Israel, FRUMKIN Amos (1) ; KARKANAS Panagiotis (2) ; BAR-MATTHEWS Miryam (3) ; BARKAI Ran (4) ; GOPHER Avi (4) ; SHAHACK-GROSS Ruth (5) ; VAKS Anton  Revue / Journal Title Geomorphology   ISSN 0169-555X  Source / Source 2009, vol. 106, no 1-2 (166 p.)  [Document : 11 p.] (3/4 p.), pp. 154-164 [11 page(s) (article)]

The subject of bottlenecks in ancient human populations is visited once again, as Amos and Hoffman propose to have found evidence for two such events, one as humans migrated out of Africa and later when a migration event into Pleistocene America occurred across the Bering Strait.

Here’s the abstract of the paper which is freely accessible:

There is a strong consensus that modern humans originated in Africa and moved out to colonize the world approximately 50 000 years ago. During the process of expansion, variability was lost, creating a linear gradient of decreasing diversity with increasing distance from Africa. However, the exact way in which this loss occurred remains somewhat unclear: did it involve one, a few or a continuous series of population bottlenecks? We addressed this by analysing a large published dataset of 783 microsatellite loci genotyped in 53 worldwide populations, using the program ‘Bottleneck’.

Immediately following a sharp population decline, rare alleles are lost faster than heterozygosity, creating a transient excess of heterozygosity relative to allele number, a feature that is used by Bottleneck to infer historical events. We find evidence of two primary events, one ‘out of Africa’ and one placed around the Bering Strait, where an ancient land bridge allowed passage into the Americas. These findings agree well with the regions of the world where the largest founder events might have been expected, but contrast with the apparently smooth gradient of variability that is revealed when current heterozygosity is plotted against distance from Africa.

The researchers suggest that their more detailed approach to investigating the data allows for a more complex picture to emerge, which in the process threw up some unexpected findings, as revealed towards the end of the paper:

Despite these complications, a rather consistent pattern emerges, with evidence of a bottleneck being strongest in the Middle East and in the easternmost East Asian/northernmost American populations. These two locations are as one might expect, but there are two additional features that are less obvious. First, the African populations, although at most loci having low t-values, do provide quite strong and consistent evidence of a bottleneck at the lowest variability loci. As discussed, this may reflect an observation bias in which loci with very low variability in Africa are unusual for some reason other than demography.

An alternative explanation is that these loci still retain the signal of an even more ancient, within-Africa event. This would be consistent with the notion that locus variability is inversely related to the antiquity of the bottleneck signal that is best retained and offers an intriguing hypothesis for future studies. The second feature is the pronounced dip in t-value between Europe/central southern Asia and East Asia. This may simply reflect a null signal between two bottlenecks, but might alternatively indicate some other demographic event such as a period of stasis and population expansion. Again, further work is desirable.

Reference:

Evidence that two main bottleneck events shaped modern human genetic diversity by  W. Amos and  J. I. Hoffman, 2009 – Published online before print October 7, 2009, doi: 10.1098/rspb.2009.1473

Just a quick note to point readers in the direction of the latest edition of the anthropology blog carnival which is hosted for the first time over at A Place Odyssey, a team of bloggers who describe themselves thus:

Known locally as the ‘landscape detectives’, we are a group of Masters students at Sheffield University studying Landscape Archaeology. This blog will show the results of our informal discussions, fieldtrips, more general landscape news,  and other things that are landscapey and/or archaeology.

Pete Cox has compiled this latest assemblage of artefacts in the guise of archaeology and anthropology posts that have appeared in the recent past, culled from some of the usual 4SH suspects as well as one or two from sites which may be unfamiliar to some, but are well worth checking out in their own right. Not only do these latest contributions cover a broad scope of stuff that should be of interest to all, but as ever, they’re all very nicely written, offering as they do, plenty of food for thought.

The next edition is due out on October 21st, for which the hosting slot is still open, so if you’d like to add your blog to the long list of those who have hosted in the past, all you need to do is drop Martin R a line via here and take it from there.