11,000 Year Old Lagoa Santa Brazil Paleoamerican Skull

While we know from a couple genetic studies there are at least two, if not 3 or more waves of colonizers, the morphological evidence is now beginning to make a lot more sense along with the genetic evidence. There’s some concern why the authors didn’t have more North American and Asian samples for comparison, but that’s almost always a critique in any anatomical study.

Two comments in the Science Now news article are particularly entertaining regarding this topic:

“Very interesting–don’t tell some of the tribes in california–they won’t be able to handle real information like this.”

“Exactly. It sounds like the Amerindians stole the land from the Paleoindians? I guess they should pay restitution, right?”

Hubbe, M., Neves, W., & Harvati, K. (2010). Testing Evolutionary and Dispersion Scenarios for the Settlement of the New World PLoS ONE, 5 (6) DOI: 10.1371/journal.pone.0011105

Highland Tibet

Little discussion, beyond correlating ecology and physical observation, is given to these. Actually I lie, the physiology of the barrel chested high altitude occupants is given a couple of sentences as well as an elevated oxygen binding capacity without concentrating their blood.

A paper published in Science several days ago tackles this latter issue. A group of scientists looked for unique alleles among Tibet highlanders and discovered 10 unique oxygen-processing alleles. I don’t have full access to the publication, so can’t tell if these genes encode for completely different functioning proteins or are differentially regulated at high altitudes.

All I can derive is that these genes seem to prevent polycythemia, edematous swelling of the lungs and brain, and hypertension of the pulmonary vasculature, which are all complications of high altitude living.  Two of these genes are EGLN1 and PPARA. PPARA is a peroxisome proliferation proteins that also is a leukotriene antagonist. That is interesting because in obstructive conditions like asthama, leukotrienes induce vasospasm and bronchconstriction. EGLN1 is also has an interesting role,

“it is a protein encoded by this gene catalyzes the post-translational formation of 4-hydroxyproline in hypoxia-inducible factor (HIF) alpha proteins. HIF is a transcriptional complex that plays a central role in mammalian oxygen homeostasis.”

These two genes were significantly associated with the decreased hemoglobin phenotype that is unique to this highland population.

Simonson TS, Yang Y, Huff CD, Yun H, Qin G, Witherspoon DJ, Bai Z, Lorenzo FR, Xing J, Jorde LB, Prchal JT, & Ge R (2010). Genetic Evidence for High-Altitude Adaptation in Tibet. Science (New York, N.Y.) PMID: 20466884

Currently, Science has put up a special section of their website dedicated to this. The news agencies are having issues with embargoes and what not, they put up articles and then take them down. But the word is out, Green and Pääbo’s project to sequence the Neandertal genome is out and there are some interesting findings:

• The comparison of 3 Neandertal samples to 5 modern human genomes showed that Neandertal genome is closer to some populations of modern humans than others
• About 10 loci had distinctly non-African hallmarks
• There’s an attributable 1-4% Neandertal ancestry to non-African modern human populations

There’s a lot more behind this all than I really have time for, unfortunately. So be sure to check out Razib, John Hawks, etc. for all the goodies.

Aside from being medically relevant, interesting on a population genetics level, and involved an Iranian family, it also caught my eye because about 3 weeks ago we covered the implications of DCC (deleted in colon cancer gene, I know — very clever!) mutations in my pathology course. DCC mutations are found in the sequence of events that lead up to a special type of familial adenomatous polyposis (FAP), known as Gardner syndromes.  These colon cancers occurs primarily on the left or descending colon. The morphology of FAP cancers lead to a napkin ring like constriction of the colon that present as alternating bouts of diarrhea and constipation. What makes them unique from other FAPs is that they have present with extracolonic manifestation, like bone cancers.

The DCC gene is on the long arm of chromosome 18. I know that it is a cell surface protein responsible for cell-to-cell and cell-to-matrix adhesion. Normally when cells proliferate, they squeeze up on each other and DCC works via contact inhibition to signal a stop in proliferation because conditions are getting too cramped. Therefore, if DCC is deleted, contact inhibition is lost and cell loses ability to proliferate, yielding a dysplastic growth.

Genbank classifies this gene as one that encodes for a netrin 1 receptor, which I did not know before I read this post. I find this really interesting in the relevance of DCC to Mirror Movements. Dr. John Nicholls,of SISSA in Trieste, Italy,  the dude for neurodevelopment, guest lectured my neuroscience course during my second term of medical school last year. I remember him describing netrins as a class of axon guiding proteins that functioned during growth and development. The hallmark experiment I remember him citing was the Oster, et al., 2004, where ganglion cell axon pathfinding in the retina and optic nerve was guided by netrin signals.

It seems that in Mirror Movements, the mutation in DCC prevents it from helping,

“nerve cells on one side of the spinal cord to stay on that side as they extend processes up and down the developing spine…. Because the protein is malformed, the body develops neural connections that route one-sided connections to both sides, producing the mirrored activity.”

I don’t have access to Science unfortunately to research the demographics of the particular SNP they discovered… So I can’t tell you of the gene frequencies… But if anyone does have access to the paper, and doesn’t emailing me, I’ll be very grateful. I love these sorts of discoveries where I learn something new and integrate what I’ve learned the past year and half of medical school!

Srour M, Rivière JB, Pham JM, Dubé MP, Girard S, Morin S, Dion PA, Asselin G, Rochefort D, Hince P, Diab S, Sharafaddinzadeh N, Chouinard S, Théoret H, Charron F, & Rouleau GA (2010). Mutations in DCC cause congenital mirror movements. Science (New York, N.Y.), 328 (5978) PMID: 20431009

Australopithecus sediba on the cover of Science

Today’s paleoanthropology new is what was eluded to by a commenter last month. I talked to some colleagues about what the commenter could have been referring to back then, and they told me Berger’s gonna be releasing his findings on UW88-50. I didn’t report on it then because of several reasons, one of which was time constraints but also because I really didn’t have much information on the fossils. There’s a lot more press out today about it and while, I don’t have much time to digest it all, I figured I’ll at least share it with you in case you’ve been living under a rock.

The remains have been given a new species classification, Australopithecus sediba and are probably descendants of Australopithecus africanus. Like every other new fossil hominin species, there’s an array of archaic and modern features. The small teeth, projecting nose, very advanced pelvis, along with the long legs are the more modern features. The archaic features are the long arms and small brain case. What is special about Australopithecus sediba is that the hominin fossil record is pretty sparse around 1.9 million years ago and this fossil helps fill that gap.

Check out the news coverage, BBC, ABC News…

Berger, L., de Ruiter, D., Churchill, S., Schmid, P., Carlson, K., Dirks, P., & Kibii, J. (2010). Australopithecus sediba: A New Species of Homo-Like Australopith from South Africa Science, 328 (5975), 195-204 DOI: 10.1126/science.1184944

Dirks, P., Kibii, J., Kuhn, B., Steininger, C., Churchill, S., Kramers, J., Pickering, R., Farber, D., Meriaux, A., Herries, A., King, G., & Berger, L. (2010). Geological Setting and Age of Australopithecus sediba from Southern Africa Science, 328 (5975), 205-208 DOI: 10.1126/science.1184950

But his documentary is still floating around. It recently aired on Australia’s public broadcaster channel ABC. ABC journalist and presenter Jonathan Holmes wasn’t too pleased his network aired this less than admirable documentary. On his show, Media Watch, he explains why. Check out the entertaining excerpt or watch the scathing clip here.

For all you aspiring paleoanthropologists and scientists out there, take this tragic case into heart and don’t make the same mistakes. You’ll leave only behind a legacy of fail.

Aside from his brown eyes, brown skin and facial hair, there are similarities (that I don’t know of because I haven’t read the full paper) which most closely resemble those found in indigenous inhabitants of eastern Siberia… Possibly the Saqqaq. The findings support the implications of the team’s mitochondrial DNA analysis of the hair previously published in Science in 2008. We’ve covered that paper before, here and here. The previous study also showed patterns of Siberian origin, and a distinct break between the Dorset culture and the ancestors of modern Inuit people.

A new, detailed and freely accessible paper, Reconstructing the Ups and Downs of Primate Brain Evolution: Implications for Adaptive Hypotheses and Homo floresiensis (provisional PDF) has just come online at BMC Biology, in which Stephen H. Montgomery et al discuss the reduced brain-size of Homo floresiensis, and suggest she is unlikely to have descended from Homo erectus, for which this is the abstract:

Background

Brain size is a key adaptive trait. It is often assumed that increasing brain size was a general evolutionary trend in primates, yet recent fossil discoveries have documented brain size decreases in some lineages, raising the question of how general a trend there was for brains to increase in mass over evolutionary time. We present the first systematic phylogenetic analysis designed to answer this question.

Results

We performed ancestral state reconstructions of three traits (absolute brain mass, absolute body mass, relative brain mass) using 37 extant and 23 extinct primate species and three approaches to ancestral state reconstruction: parsimony, maximum likelihood and Bayesian Markov-chain Monte Carlo. Both absolute and relative brain mass generally increased over evolutionary time, but body mass did not. Nevertheless both absolute and relative brain mass decreased along several branches. Applying these results to the contentious case of Homo floresiensis, we find a number of scenarios under which the proposed evolution of the Homo floresiensis brain appears to be plausible, dependent on body mass and phylogenetic position.

Conclusions

Our results confirm that brain expansion began early in primate evolution and show that increases occurred in all major clades. Only in terms of an increase in absolute mass does the human lineage appear particularly striking, with both the rate of proportional change in mass and relative brain size having episodes of greater expansion elsewhere on the primate phylogeny. However, decreases in brain mass also occurred along branches in all major clades, and we conclude that, while selection has acted to enlarge primate brains, in some lineages this trend has been reversed.

Further analyses of the phylogenetic position of Homo floresiensis and better body mass estimates are required to confirm the plausibility of the evolution of its small brain mass. We find that for our dataset the Bayesian analysis for ancestral state reconstruction is least affected by inclusion of fossil data suggesting that this approach might be preferable for future studies on other taxa with a poor fossil record.

There’s a pretty good write-up over at A Primate of Modern Aspect, from which this is excerpted:

It’s extremely important for most of your organs to increase with body size.  For example, a bigger animal needs to pump more blood, so it needs a bigger heart.  A bigger animal eats more food and needs a bigger liver.  There are certain areas of the brain that increase allometrically with body size- usually areas that are in charge of motor skills.  If you’ve got bigger legs, you’ve got bigger muscles, and you need more neural projections in order to control them.  But does a larger animal need to think more?  Will it benefit from an extra few cubic centimeters of neocortex?  Probably not, so it’s not worth the extra time and energy it takes to develop that neocortex.

And that sort of brings us to an important question in evolutionary neurobiology: Does absolute brain size matter, or is it solely brain size relative to body size?  Brains that are absolutely larger have more neurons, which could have important cognitive implications.  But how many of those extra neurons are just being used to control the physiological functions of the body?

Does size even tell us anything at all?  Any way you look at it, brain size is a crude measurement of cognitive ability.  In an ideal world, we would know the proportion of each of the different regions of the brain in each species and go from there.  But, those kinds of measurements are hard to obtain in living species, and impossible in fossils.  Ralph Holloway has been saying since 1967 that there has got to be a better way than just plain ol’ cranial capacity… but other than noting the relative position of different sulci and gyri on endocasts, there isn’t too much else to be done.

The diminished brain size of LB1 has been remarked upon ever since the initial discovery, at is generally supposed that the stone tools found in context would have required a hominid with a larger brain in order to deploy the cognitive capacity needed for such behaviours, leading some to suggest that they were copies of others made by unknown AMH others present on the island of Flores. This in turn raised the question of from what or whom Liang Bua 1 had descended – according to the interpretation by zinjanthropus, if LB1 is descended from either H.georgicus found at Dmanisi, or H.habilis, the size of her brain is much more in accordance than had the descent been from the H.erectus from Ngangdong. Here’s a related note from the paper, which I’m sure will be the subject of extended discussion in the near future:

From our analyses  of evolution of H. floresiensis brain size under different phylogenetic  hypotheses, we conclude that the evolution of H. floresiensis is consistent with  our results across the primate phylogeny if it either evolved from populations  of H. habilis or Dmanisi hominin by insular dwarfism, or under Argue et al.’s  [43] proposed phylogenetic scenarios, and if H. floresiensis had a body mass  towards the lower end of the range of estimates obtained from skeletal  remains. In this respect we note that Brown et al. [26] suggested the lower  body mass estimates are probably most appropriate, assuming H. floresiensis  shared the lean body shape typical of Old World tropical modern humans.

If  this were true we estimate the evolution of H. floresiensis involved a  reasonable decrease in absolute brain mass, but an increase in relative brain  size.  Our analysis, together with studies of brain size in island populations of living primates[41, 42], therefore suggests we should perhaps not be  surprised by the evolution of a small brained, small bodied hominin, although  further clarification of the relationships between H. floresiensis and other  hominins are required to confirm this observation. Finally, our analyses add to  the growing number of studies that conclude that the evolution of the human  brain size has not been anomalous when compared to general primate brain  evolution [59, 61 91-94].

Reference:

Reconstructing the Ups and Downs of Primate Brain Evolution: Implications for Adaptive Hypotheses and Homo floresiensis

Abstract – Provisional PDF

Stephen H Montgomery , Isabella Capellini , Robert A Barton and Nicholas I Mundy

BMC Biology 2010, 8:9doi:10.1186/1741-7007-8-9

The gist of his latest paper, as reported at Science Daily and Physorg is that Neanderthals in west and southern Iberia survived no later that 37,000 calendar years ago, (as opposed to much later estimates indicating they could have survived up until the Last Glacial Maximum), which in the opinion of the authors means that AMH and Neanderthals co-existed in Europe for no more than 5,000 years, and furthermore, that the case for Lagar Velho I being an AMH/Neanderthal artefacts of admixture, is thus strengthened. Moreover, the authors conclude that climate change caused disruption to interactive networks, and brought AMH and Neanderthals into direct contact south of the so-called Ebro Frontier system, ultimately causing the demise of the latter.

Here’s the abstract from the paper itself:

Background

Neandertals and the Middle Paleolithic persisted in the Iberian Peninsula south of the Ebro drainage system for several millennia beyond their assimilation/replacement elsewhere in Europe. As only modern humans are associated with the later stages of the Aurignacian, the duration of this persistence pattern can be assessed via the dating of diagnostic occurrences of such stages.

Methodology/Principal Findings

Using AMS radiocarbon and advanced pretreatment techniques, we dated a set of stratigraphically associated faunal samples from an Aurignacian III–IV context excavated at the Portuguese cave site of Pego do Diabo. Our results establish a secure terminus ante quem of ca.34,500 calendar years ago for the assimilation/replacement process in westernmost Eurasia. Combined with the chronology of the regional Late Mousterian and with less precise dating evidence for the Aurignacian II, they place the denouement of that process in the 37th millennium before present.

Conclusions/Significance

These findings have implications for the understanding of the emergence of anatomical modernity in the Old World as a whole, support explanations of the archaic features of the Lagar Velho child’s anatomy that invoke evolutionarily significant Neandertal/modern admixture at the time of contact, and counter suggestions that Neandertals could have survived in southwest Iberia until as late as the Last Glacial Maximum.

The Ebro Frontier is mentioned at Physorg:

Although the reality of this ‘Ebro Frontier’ pattern has gained wide acceptance since it was first proposed by Professor Zilhão some twenty years ago, two important aspects of the model have remained the object of unresolved controversy: the exact duration of the frontier; and the causes underlying the eventual disappearance of those refugial Neanderthal populations (ecology and climate, or competition with modern human immigrants)…

…Professor Zilhão said: “I believe the ‘Ebro frontier’ pattern was generated by both climatic and demographic factors, as it coincides with a period of globally milder climate during which oak and pine woodlands expanded significantly along the west façade of Iberia.

“Population decrease and a break-up of interaction networks probably occurred as a result of the expansion of such tree-covered landscapes, favouring the creation and persistence of population refugia.

“Then, as environments opened up again for large herbivore herds and their hunters as a result of the return to colder conditions, interaction and movement across the previous boundary must have ensued, and the last of the Neanderthals underwent the same processes of assimilation or replacement that underpin their demise elsewhere in Europe five millennia earlier.”

Clearly this will come as disconcerting news to those who contend that in fact Neanderthals survived a good few millennia later than 37 cal kya, and might well argue that a single cave – or data point – can’t be construed to represent the latest appearance date of Neanderthals across the entire Iberian peninsular, and it remains to be seen whether other sites in southern and northern Iberia, such as Carihuela and Esquilleu will refute the conclusions of this paper.

Much of content of the paper itself is given over to an exhaustive description of how the cave was re-examined and some of the contents re-dated, along with brief reference to an Aurignacian lithic assemblage, the Dufour bladelets, as described here:

Bearing in mind the palimpsest nature of cave deposits, the dating of layer 2 to the time range of the Aurignacian III–IV does not completely reject the possibility that the artifacts contained therein entered the site at some point in time during the hiatus between the deposition of layers 2 and 3, i.e., in the ca.35–43 ka cal BP interval. Confirmation that the Pego do Diabo Dufour bladelets are indeed Aurignacian III–IV therefore requires assessment of whether their metrical and formal attributes are consistent with alternative assignments to earlier stages of the technocomplex.

A persistent source of confusion in the study of the Aurignacian is the vague, catch-all original definition of the “Dufour bladelet” type: “bladelet with a curved profile, presenting a fine, marginal, semi-abrupt retouch, along one of the edges only (in which case it can be either ventral or dorsal) or along both edges (in which case it is always alternate)” [57]. As a result, over the years, practitioners have subsumed under this category an extremely varied range of microliths with very little in common in terms of blank technology, mode of retouch, and overall shape.

A case in point is the putative presence of Dufour bladelets in Châtelperronian level X of the Grotte du Renne, at Arcy-sur-Cure [77], which some have used to support the twin notions that the site is heavily disturbed and that the numerous ornaments found in level X originated in Aurignacian level VII, where Dufour bladelets are abundant [78]–[79]. In fact, the few level X items in question represent one end of the variation of the “retouched blade” tool type. They are not bladelets but blades (their average width is 13.5 mm), and they display a technology of blank production that is distinctively Châtelperronian [80].

The authors note that very little is known about the Aurigncian/Gravettian transition in Europe, and that this research tallies with other sites regarding the onset of the Gravettian in Europe:

The Aurignacian-to-Gravettian transition is one of the least known periods of European prehistory, explaining why the evidence from such a small site as Pego do Diabo can contribute to our understanding of this process. In particular, our results put the west European evidence in line with that from central Europe, where the earliest Gravettian is now dated to the ca.29–30 ka ¹⁴C BP interval [95].

This transition was therefore penecontemporaneous at the continental scale: the south German pattern is no instance of precocity, as in the Kulturpumpe model [95], nor is it necessarily a byproduct of post-depositional displacement of samples derived from underlying Aurignacian levels, as others have proposed [30]…

…Where the emergence of anatomical modernity is concerned, Pego do Diabo establishes a secure terminus ante quem of ca.34.5 ka cal BP for the process in central Portugal, where, on current evidence [19], [39], [41], the terminus ante quem for the demise of Neandertals is ca.35.5 ka cal BP (Table S7; Figure 12).

This has major implications for the interpretation of the archaic features in the anatomy of the Lagar Velho child. With the last of the region’s Neandertals dating to five millennia before the child was borne, crossbreeding between immediate ancestors (e.g., parents or grandparents) drawn from distinct “modern” and “Neandertal” gene pools is empirically untenable. Therefore, those features must represent evolutionarily significant admixture at the time of contact.

As ever, the paper bears worth reading in full, even if as remarked over at Gene Expression, some of the detail seems a little dense to those not fully apprised in archaeological research, lithic manufacture techniques, or a familiarity with industries thereof. I’m going to end this post though at Gorham’s Cave, Gibraltar a site previously proposed to have witnessed the last known Neanderthals:

Given that no secure evidence exists elsewhere for peninsular Neandertals to have persisted beyond the 37th millennium cal BP, and that available archeological proxies place the emergence of anatomical modernity across southwest Iberia no later than the beginning of the 36th, the younger dates obtained for the Middle Paleolithic of Gorham’s Cave must be considered anomalous [50].

These dates are part of a large set of results, mostly within the expected range but widely scattered and with no correlation between age and stratigraphic depth. Combined with the microscopic size of the charcoal samples used, this pattern means that incomplete decontamination and post-depositional intrusion from the overlying Upper Paleolithic are viable explanations for the outliers.

Moreover, the samples come from a trench in the back part of the site where find densities are very low (five artifacts per cubic meter) and a non-diagnostic Upper Paleolithic stone tool component may well exist alongside the few clearly Middle Paleolithic items. Finally, Upper Paleolithic deposits of later Aurignacian affinities exist in the porch area of the site and are well dated by numerous samples to ca.34 ka cal BP (Table S7; Figure 12). This dating is in line with the evidence from Pego do Diabo, and precludes the possibility that the back area of Gorham’s continued to be used by Middle Paleolithic Neandertals beyond that point in time.

Some might wonder whether the case for Pego do Diabo is being overstated here, or that other data from Gorham’s Cave are being re-interpreted to fit with the latest data presented – either way, I somehow doubt that this will be the final word in the debate, or that the Neanderthal/AMH transition was as neat and tidy as suggested.

No contemporary human fossils were found in direct association with the artifacts at either site – but can we safely attribute all post-Mousterian lithic industries to AMH alone?

However, this figure of 5,000 years as a co-existence spell is especially interesting as it closely resembles a similar proposed 5,000 year interlude in Australia, whereby another round of re-analysis has suggested that there was an extinction of large mammals there at 40 kya, some 5,000 years after the proposed date for the arrival of humans on the continent. The story is reported in Stuff, a New Zealand news site, the details of which were sent to me by Terry T.

Giant marsupials, reptiles and flightless birds that once roamed Australia became extinct about 40,000 years ago, later than had been thought and some 5,000 years after humans arrived, a new study suggests.  Controversy has long surrounded when such creatures became extinct in Australia. New equipment that can date teeth and bones has solved the puzzle, Australian researchers said in the latest issue of the journal Science.

“For a long time, we couldn’t measure bone and teeth, or how old they (animals) were when they died, that is, when they went extinct,” paleontologist Barry Brook at the University of Adelaide in southern Australia told Reuters by telephone.

One of the new techniques used in the latest research was uranium thorium dating, which can gauge when uranium was taken up into the animal’s teeth when it was still alive.

The question as to when the last of these creatures died in Australia surfaced when other researchers began finding fossils, along with stone tools, in Cuddie Springs in New South Wales about 100 years ago and again over the past 30 years.  They analysed surrounding sediments and found that they dated back to 30,000 years ago, contradicting evidence elsewhere in Australia which showed that the animals became extinct far earlier, or at least 40,000 years ago.

Faunal remains that had previously been dated to 30,000 years by the sediments in which they were found have now been re-dated, through the use of uranium/thorium, with the new age placing them at 40,000 years old – taken in conjunction with a suggested first-appearance date 0f 47 kya for humans, the extinction event now appears to have been lightning quick, geologically speaking, with the clear implication that it was the arrival of humans that caused a continent-wide extinction event.

It seems – to me at least – extraordinary that what was probably an initially small population of humans could have had such a widespread and devastating impact on such a grand scale, and it will be interesting to see the response of others who claim to have found no evidence that the remains of extinct Pleistocene mammals there met their fate at the hands of humans. Moreover, a human presence in Australia has been proposed for as early as 50-60 kya, which would make the extinction at 40 kya a more drawn-out affair.

We return to Iberia, from where Zilhão give his team’s version of the sequence of events that led to the final days of Iberian Neanderthals:

Why, south of the Ebro drainage system, the replacement/assimilation process occurred much later than elsewhere in Western Europe, remains a “big issue.” Our hypothesis is that climatic and demographic factors are involved [13], [21]–[22]. North of the Pyrenees, the impact of a severely cold iceberg event (Heinrich Event 4), aggravated, in central and eastern Europe, by the effects of the Phlegraean Fields caldera explosion, must have caused a population crash.

At the same time, to the south, and especially so along the Atlantic façade, oak and pine woodlands expanded significantly during the period of the “Ebro Frontier,” which, globally, was one of generally milder climate (GIS8; Greenland Interstadial 8); by comparison with what happened in Iberia at the time of the Tardiglacial/Early Holocene transition, population decrease and a break-up of interaction networks probably occurred as a result of the expansion of such tree-covered landscapes.

The net result may have been one where, for modern human groups settling the foothills of the Cantabro-Pyrenean mountains, southward expansion (or networking) may have become neither possible nor desirable. Then, as population numbers recovered and the long GIS8 interval came to an end, with southwest Iberian environments opening up for large herbivore herds and their hunters as a result of the return to stadial conditions, interaction and movement across the previous boundary must have ensued, with inevitable consequences for the Neandertal refugia of westernmost Eurasia.

It’s important to note that a range of simultaneous contributing factors are proposed, though whether some of those Neanderthal refugia persisted in more isolated locations is something yet to be determined.

Reference:

Zilhão J, Davis SJM, Duarte C, Soares AMM, Steier P, et al. (2010) Pego do Diabo (Loures, Portugal): Dating the Emergence of Anatomical Modernity in Westernmost Eurasia. PLoS ONE 5(1): e8880. doi:10.1371/journal.pone.0008880

Editor: John Hawks, University of Wisconsin, United States of America

First up is this post at Gene Expression, European man perhaps a Middle Eastern farmer, in which Razib Khan discusses the findings of a recent paper at PLoS Biology, A Predominantly Neolithic Origin for European Paternal Lineages – for which this is the abstract:

The relative contributions to modern European populations of Paleolithic hunter-gatherers and Neolithic farmers from the Near East have been intensely debated. Haplogroup R1b1b2 (R-M269) is the commonest European Y-chromosomal lineage, increasing in frequency from east to west, and carried by 110 million European men. Previous studies suggested a Paleolithic origin, but here we show that the geographical distribution of its microsatellite diversity is best explained by spread from a single source in the Near East via Anatolia during the Neolithic.

Taken with evidence on the origins of other haplogroups, this indicates that most European Y chromosomes originate in the Neolithic expansion. This reinterpretation makes Europe a prime example of how technological and cultural change is linked with the expansion of a Y-chromosomal lineage, and the contrast of this pattern with that shown by maternally inherited mitochondrial DNA suggests a unique role for males in the transition.

Razib offers some background to the ongoing debate…

For the past few decades there has been a long standing debate as to the origins of modern Europeans. The two alternative hypotheses are:

* Europeans are descended from Middle Eastern farmers, who brought their Neolithic cultural toolkit less than 10,000 years ago.

* Europeans are descended from Paleolithic hunter-gatherers, who acculturated to the farming way of life through diffusion of ideas.

…and further notes:

In this unsettled landscape comes a new paper which turns some assumptions about Y chromosomal variation in Europe on its head. The focus is on a subclade of the R1b haplogroup, which has its highest frequencies in Western Europe, in particular along the Atlantic fringe. The pattern of variation has led many to infer that this lineage, in particular the R1b1b2 haplgroup, is a marker of the Paleolithic populations of Western Europe. The high frequency of this marker among the Basques in particular is seen as evidence of this, because this group speaks a language which is a pre-Indo-European isolate (the Basques are used as a Paleolithic reference group in many papers). But perhaps not…

…One issue to note is that it seems likely that if the model presented here is true, that R1b1b2 is newcomer from the Middle East which rapidly expanded in frequency across Western Europe, it’s going to be hard to getting the clarity you need from molecular clock based methods because the demographic processes occurred rather rapidly. We know from archaeology that agricultural societies could sprout up almost instantaneously, as if they simply transplanted their culture to new locales. Some of this likely occurred via sea, using the Mediterranean and the Atlantic fringe…

…The authors point out that in places like Japan and India there is a great deal of circumstantial evidence for agriculture resulting in the expansion of particular lineages, so the preponderance of acculturation in Europe as the mode of transmission seems atypical…

…One analog might be the emergence of mestizos in the New World, who have predominantly European male lineages and native female lineages. Finally, one question a friend brought up: if the higher frequency of R1b1b2 is a function of the wave of advance, why is it the same haplogroup all along the wave front? Standard population genetic theory tells us that fragmented small groups will tend to lose genetic diversity and fix particular alleles, but those alleles are not going to be the same. It seems that it is more plausible that there were serial bottlenecks through coastal migrations, and eventually these expanded inland once they stumbled onto the northwest European plain. But that’s just speculation.

For further discussion, please see Dieneke’s whileYann Klimentidis mentions both this paper and another, namely Genetic discontinuity between local hunter-gatherers and central Europe’s first farmers.

Next it’s over to Gambler’s House, and an article titled The Supposed Linguistic Evidence for the Spread of Agriculture, whose introductory notes state the following:

The prehistoric peoples of the American Southwest were agriculturalists.  Different societies may have calibrated their mix of farming, hunting, and gathering differently, but they all seem to have done all three eventually, and for most it’s quite apparent in the archaeological record that farming was the predominant method of subsistence.  The crops they grew were corn, beans, and squash, the classic triad of North American agriculture.  These plants are not native to the Southwest, however, so they must have been introduced at some point from Mesoamerica, where they originated.  The introduction of corn, in particular, must have also involved the introduction of agricultural techniques, since it can’t grow without help from humans.  All this is pretty uncontroversial among Southwestern archaeologists.

The nature of the introduction of agriculture, however, has been a point of more dispute.  The main arguments have to do with how long it took after the introduction of maize for the societies growing it to become totally dependent on it and thus become primarily agriculturalists rather than hunter-gatherers.  One view, espoused by Chip Wills at UNM, sees the introduction of corn as being gradual, perhaps filtering up from one hunter-gatherer group to another, and increasing dependence on it as taking place in the context of hunter-gatherer subsistence decisions and environmental fluctuations, with the total switch to a fully agricultural lifestyle not taking place until maybe as late as the Pueblo II period.  The other view, associated most strongly with R. G. Matson of the University of British Columbia, sees the introduction of maize as having been rapid and involving a totally different lifestyle from Archaic hunter-gatherers from the get-go.

There follows an in-depth discussion of the theories of Australian Professor of Archaeology, Peter Bellwood, who contends that…

… the enormous geographical extent of some language families by associating them with the spread of particular agricultural traditions.  This has been somewhat controversial, particularly in regard to Indo-European, as it produces a very specific answer (given Bellwood’s specific assumptions) to the vexing question of where a given language family originated, often called its Urheimat.  Since Bellwood argues that hunter-gatherers are unlikely to adopt agriculture, whether on their own or when exposed to it by contact with farming groups, his model predicts that the Urheimat of a given language family must be somewhere in the region where its agricultural tradition originated.  For Indo-European this means the Fertile Crescent rather than the Eurasian Steppe, which has been the preferred answer for many Indo-Europeanists on various grounds.  This has led to much controversy.

And continuing the language thread, we return to Gene Expression, where another article, Complex societies = simple languages, goes on to discuss a paper at PLoS ONE, Language Structure Is Partly Determined by Social Structure, for which this is the introduction:

Although the largest languages are spoken by millions of people spread over vast geographic areas, most languages are spoken by relatively few individuals over comparatively small areas. The median number of speakers for the 6,912 languages catalogued by the Ethnologue is only 7,000, compared to the mean of over 828,000 [1]. Similarly, for the 2,236 languages in our sample (Figure 1), the median area over which a language is spoken is about the size of Luxembourg or San Diego, California (948 km²). The mean area is about the size of Austria or the US state of Maryland (33,795 km²).

Languages also differ dramatically in the proportion of individuals who speak the language natively (L1 speakers) to those who learned it later in life (L2 speakers) (Table S1). Although there are numerous counter-examples (Text S1), languages spoken by millions of people have a greater likelihood of coming into contact with other languages and of having numerous nonnative speakers compared to languages spoken by only a few thousand people.

This is not surprising: a language spoken by more people is more likely to encompass a larger and more diverse area and include speakers from varying ethnic and linguistic backgrounds. Conversely, languages spoken by a thousand or even fewer individuals tend to be spoken in highly circumscribed locales (Text S2). Overall, languages with smaller speaker populations are more likely to be spoken by more socially cohesive groups [2] than languages that have millions of speakers.

And by a curious coincidence, news comes to today of the Evolang 2010 Conference due to take place in Utrecht, Netherlands, between this coming April, 14-17th.

To finish up, there’s a nice post over at PaleoFuture, The Victory of Chemistry over Agriculture, which begins by noting:

To many people of the year 2010 the 1953 book, The Road to Abundance, is a heretical, nightmarish vision of the future. Chemicals and factory farming are seen as the logical next step in the evolution of food production for mankind.  Jacob Rosin, co-writing with Max Eastman, describes the eventual “victory of chemistry over agriculture,” and mankind’s “bondage to the planet.”

The ultimate goal of Rosin’s ambition was to be “more efficient than nature.” In his advocacy of a completely synthetic diet Rosin called into question both the definition and the benefit of “natural foods.”

See also: Telegraph – Giant Cattle to be Bred back from Extinction – via John Hawks

This post in turn links to another, “Factory” Farms of the Future (1961) from which the image at top is taken.

References:

Balaresque P, Bowden GR, Adams SM, Leung H-Y, King TE, et al. (2010) A Predominantly Neolithic Origin for European Paternal Lineages. PLoS Biol 8(1): e1000285. doi:10.1371/journal.pbio.1000285

Genetic discontinuity between local hunter-gatherers and central Europe’s first farmers.
Bramanti B, Thomas MG, Haak W, Unterlaender M, Jores P, Tambets K, Antanaitis-Jacobs I, Haidle MN, Jankauskas R, Kind CJ, Lueth F, Terberger T, Hiller J, Matsumura S, Forster P, Burger J.
Science 2009 Oct 2;326(5949):137-40.

Lupyan G, Dale R (2010) Language Structure Is Partly Determined by Social Structure. PLoS ONE 5(1): e8559. doi:10.1371/journal.pone.0008559