January 9, 2017

Extensive ancient Iberian mtDNA analysis

A very interesting thesis on Iberian ancient mitochondrial DNA is available (found via Bell Beaker Blogger):

Christina Roth, Once upon a time in the West : paleogenetic analyses on Mesolithic to Early Bronze Age individuals from the Iberian Peninsula. University of Mainz (thesis), 2016. Freely availableLINK

As all theses, it is very extensive, and I can only make some comments here (space and time are always too limited, you know), hoping to grasp the most interesting aspects of it.

First of all Roth finds that Iberian hunter-gatherers (HGW in the paper) were not quite like Central European ones (HGC), at least not in the mtDNA. Instead, in this aspect the Central European hunter-gatherers were closer to Eastern European ones (HGE), as well as to the Pitted Ware late subneolithic population of Gotland.



Iberia-only mtDNA analysis


This will be a recurrent issue along the analysis she makes. But let's focus on Iberia by the moment. Notice that she does not just use her own data but also from many other sources, including some unpublished materials, this makes a bit difficult to follow all the details, so I feel I can only focus on the statistical analysis she makes and which is the core of the thesis.

Annotated by me, because I found the abbreviations quite hard to follow

The general overview is confirmed, with minor variations, in the cluster analysis (which I also took the liberty of annotating, but take my notes for what they are: mere scribbling on the margin in an attempt to better understand the data, nothing else):



Particular care not to take the arrows of my notes too seriously: they are just conceptual, a very loose sequencing of the available data for a very tentative visualization of it. If it helps you, cool, else ignore please.

In any case, it seems clear cluster 2 is more influenced by hunter-gatherer genetics and that, with the data available in this study, we reach the end of the timeline within it in the following regions: Upper Ebro and Basque Country (data up to Late Neolithic but see my own 2013 compilation for a longer period), Southern Iberia (up to Chalcolithic) Southeast and Northeast, this one after originally being in the "more Neolithic" cluster 1 (in fact the author does argue for Catalonia as main "gate" for Neolithic genetics into Iberia on light of the available data, which does not include another important "gate", the SE one, for lack of data for the early period).

Inversely, cluster 1 is more influenced by "farmer" genetics, first detected in the Northeast (Catalonia and nearby areas of Aragon) but then also affecting the Northern Plateau and the West (Central Portugal). This last is very important because it is here where a key civilizational hub, the oldest known civilization of the Atlantic shores, emerged in the Chalcolithic, playing a key role in the wider Megalithic and Bell Beaker phenomena. I have at times speculated that it might be the origin of "modernity" in Western European genetic pools but on light of this data I have to recant, the origin should be elsewhere, probably in/around what is now France (and therefore it's not likely to be directly related to Bell Beaker, except maybe in the islands, but rather to Michelsberg/SOM, Artenacian and such -- always in wait of more data, just a cautious hypothesis). 

Finally the farmer-leaning cluster reaches the Southern Plateau, near Madrid, what suggests a N→S move of the then-forming Cogotas I herder culture, rather than the opposite. 

What we do see is not inconsistent with modern Iberian genetics anyhow: while Central Europe seem to have seen an increase of "hunter-gatherer" genetics along time, in Iberia the main tendency is the opposite: an increase of "farmer" genetics and further dilution of the aboriginal genetic pool. There is however at least one clear exception in the Northeast and that is also consistent with modern Iberian genetics. Some regions (south, southeast and the totally unknown northwest) have only fragmentary sequences here, so unclear, although the final tendency, up to the Bronze Age, is to cluster 2b (i.e. mixed but rather tending to "hunter-gatherer" genetics).

To finish with the Iberia-only bloc, notice that these are the lineages found among early Iberian farmers by region (in color those haplogroups associated to the arrival of Neolithic per the available data):



Notice how the pool in the Northern region is quite modern-like, not yet exactly as it is locally today but it would pass quite unnoticed in a map of Europe.


Iberia and the rest of Europe


What about the pan-European context (with the usual huge blanks in France, Britain, etc.)? Quite interesting as well:

Annotated by Maju on fig. 23 (click to enlarge)



As mentioned before, the Iberian hunter gatherers (HGW) appear clearly distinct from their Central and Eastern cousins in the mtDNA analysis. And with all this Iberian dataset it becomes apparent that there seem to be two "zones of admixture": one for Iberians and another for Central Europeans, the difference being on which aborigines they mix with. 

Notice that it is not possible to differentiate here between local Central European and intrusive Eastern European admixture, as both aboriginal hunter-gatherer populations appear closely related in all analyses (maybe an artifact of the sampling strategy or maybe actually relevant, can't say). 

It also caught my eye that a German site (Blätterhöhle, Westfalia, famed because farmer and hunter-gatherers living side by side were located there some years ago), clusters intensely with Iberian hunter-gatherers and related populations. I have to research more on this matter (which I had ignored so far) but I suspect it may be very relevant, because we could get an even longer chain of early "modern" mtDNA pools, adding this site to Paternabidea (Navarre) and Gurgy (Burgundy), spanning a long stretch of Western Europe, an area quite neglected by archaeogenetics so far, it must be said.

It is also worth mentioning that UC (which I believe stands for Unetice Culture) pulls the "Central European zone of admixture" in the PCA downwards, with a polarity of its own, a polarity that should probably be considered as specifically Indoeuropean. 

The cluster analysis confirms much of what I just said above, not annotated for a change:



We see very clearly here a larger cluster more influenced by "farmer" genetics and a smaller one that includes all pre-Neolithic aborigines, plus two populations already post-Neolithic but clearly identifiable as at least largely aboriginal (PWC and BLA), plus a subcluster of Neolithic Iberians, from the North (NSE and EVN) and the West (CPE). 

The author notices that: Bernburg (BEC) and Funnel Beaker (FBC) samples (...) show almost no significant differences to any Iberian group, except to the Early Neolithic of Northern Spain (NSE) and Chalcolithic of East Spain (ESC). Hard to interpret but worth noticing, no doubt.

And there is a lot more in the thesis but I can only review so much, so take a look and tell me and the World if I'm missing something of relevance or you feel I'm misinterpreting something or whatever.

January 1, 2017

Chad's Eurasian genetic input similar to that in Ethiopia

Quickies

Marc Haber et al. Chad Genetic Diversity Reveals an African History Marked by Multiple Holocene Eurasian Migrations. AJHG 2016. Open accessLINK [doi:10.1016/j.ajhg.2016.10.012]

Summary

Understanding human genetic diversity in Africa is important for interpreting the evolution of all humans, yet vast regions in Africa, such as Chad, remain genetically poorly investigated. Here, we use genotype data from 480 samples from Chad, the Near East, and southern Europe, as well as whole-genome sequencing from 19 of them, to show that many populations today derive their genomes from ancient African-Eurasian admixtures. We found evidence of early Eurasian backflow to Africa in people speaking the unclassified isolate Laal language in southern Chad and estimate from linkage-disequilibrium decay that this occurred 4,750–7,200 years ago. It brought to Africa a Y chromosome lineage (R1b-V88) whose closest relatives are widespread in present-day Eurasia; we estimate from sequence data that the Chad R1b-V88 Y chromosomes coalesced 5,700–7,300 years ago. This migration could thus have originated among Near Eastern farmers during the African Humid Period. We also found that the previously documented Eurasian backflow into Africa, which occurred ∼3,000 years ago and was thought to be mostly limited to East Africa, had a more westward impact affecting populations in northern Chad, such as the Toubou, who have 20%–30% Eurasian ancestry today. We observed a decline in heterozygosity in admixed Africans and found that the Eurasian admixture can bias inferences on their coalescent history and confound genetic signals from adaptation and archaic introgression.

Worth a read no doubt but careful, careful, careful with their chronological guesstimates. Their starting point is the assumption (once and again demonstrated all kinds of WRONG) of:

Eurasians and Africans diverged around 60,000–80,000 ya and subsequently had different patterns of population-size changes: in particular, compared with Africans, the Eurasian population experienced a sharp decrease in size ∼60,000 ya.

So add around 65-70% (x1.7) to all dates, else you are bound to fall in the pit of molecular-clock-o-logical self-complacent pseudoscience. So where it reads c. 6-7 Ka for the first migration (R1b-related), it should be 10,000 years ago (which is the actual dating of Afroasiatic expansion by most accounts, with origin not exactly in "Eurasia" but rather in or near Sudan, where those Eurasian lineages, R1b and J1, had since long before most likely), and when they say 3 Ka ago, it's probably 5000 years ago, within the context of Neolithic inflows possibly: 3000 years ago was already well into Ancient Egypt and peoples just did not cross it without proper paperwork anymore, actually 3000 years ago is the Bronze Age collapse and Egypt, Lower Egypt specifically, fell to Africans, to Libyans and other Berbers known as Meshwesh (Amazigh, probably from modern Tunisia) to be precise.

Dr. Haber: time to update your clock, it just doesn't work, and you are confusing people to no avail.

Forests burnt in Ice Age Europe

Quickies


Jed O. Kaplan et al., Large Scale Anthropogenic Reduction of Forest Cover in Last Glacial Maximum Europe. PLoS ONE 2016. Open accessLINK [doi:10.1371/journal.pone.0166726]

Abstract

Reconstructions of the vegetation of Europe during the Last Glacial Maximum (LGM) are an enigma. Pollen-based analyses have suggested that Europe was largely covered by steppe and tundra, and forests persisted only in small refugia. Climate-vegetation model simulations on the other hand have consistently suggested that broad areas of Europe would have been suitable for forest, even in the depths of the last glaciation. Here we reconcile models with data by demonstrating that the highly mobile groups of hunter-gatherers that inhabited Europe at the LGM could have substantially reduced forest cover through the ignition of wildfires. Similar to hunter-gatherers of the more recent past, Upper Paleolithic humans were masters of the use of fire, and preferred inhabiting semi-open landscapes to facilitate foraging, hunting and travel. Incorporating human agency into a dynamic vegetation-fire model and simulating forest cover shows that even small increases in wildfire frequency over natural background levels resulted in large changes in the forested area of Europe, in part because trees were already stressed by low atmospheric CO2 concentrations and the cold, dry, and highly variable climate. Our results suggest that the impact of humans on the glacial landscape of Europe may be one of the earliest large-scale anthropogenic modifications of the earth system.



Not sure what to think, really. In any case the data they manage and share with us is very much worth taking a look at.


Reconstructing Sardinian population history

A very interesting pre-pub study, dealing with Sardinian genetics in great sub-national detail but also within the wider European and Mediterranean context, became available in the last weeks. I won't probably be able to make justice to it here, so please take a look yourselves.

Charleston W.K. Chiang et al., Population history of the Sardinian people inferred from whole-genome sequencing. BioRXiv 2016. Open access pre-pubLINK [doi:10.1101/092148]

Abstract

The population of the Mediterranean island of Sardinia has made important contributions to genome-wide association studies of traits and diseases. The history of the Sardinian population has also been the focus of much research, and in recent ancient DNA (aDNA) studies, Sardinia has provided unique insight into the peopling of Europe and the spread of agriculture. In this study, we analyze whole-genome sequences of 3,514 Sardinians to address hypotheses regarding the founding of Sardinia and its relation to the peopling of Europe, including examining fine-scale substructure, population size history, and signals of admixture. We find the population of the mountainous Gennargentu region shows elevated genetic isolation with higher levels of ancestry associated with mainland Neolithic farmers and depleted ancestry associated with more recent Bronze Age Steppe migrations on the mainland. Notably, the Gennargentu region also has elevated levels of pre-Neolithic hunter-gatherer ancestry and increased affinity to Basque populations. Further, allele sharing with pre-Neolithic and Neolithic mainland populations is larger on the X chromosome compared to the autosome, providing evidence for a sex-biased demographic history in Sardinia. These results give new insight to the demography of ancestral Sardinians and help further the understanding of sharing of disease risk alleles between Sardinia and mainland populations.

The authors call to some question the extreme simplicity of the three populations model of Lazaridis and subsequent studies. They do not flatly reject it but it seems that the lack of nuance bothers them a lot, as it does to me. This is quite clear when they find once and again Sardinian-Basque lines of relationship without going through Italian, Spaniard or French intermediaries, also when they face the issue of the largest Y-DNA haplogroups in the island, I2a1a (M26, almost exclusively a Sardinian and Pyrenean haplogroup) and R1b1a2 (M269), which are not typically associated with Neolithic farmers, suggesting that there is more to Neolithic settlement than meets the eye in the too simplistic three populations' model. They even seem to consider if Paleolithic peoples from Sardinia itself or maybe some other locations contributed heavily to what they feel is a sex-biased genetic pool.

They do confirm that Sardinians have both strong "Neolithic" (Stuttgart) and "Paleolithic" (Lochsbour) ancestry and no (negative even) "Steppe" (Yamnaya) one, although this last is truer for the most isolated sub-populations than for the more cosmopolitan ones. 

They also estimate that Sardinians have been generally isolated from the rest of Europeans for some 330 generations, what reads as approx. 9900 years, i.e. since the very early Neolithic settlement of the island. We would actually have to reduce that time span a bit but within reason, else it becomes Epipaleolithic in fact, what is most unlikely. Alternatively, as the main comparison is Northern Europe, this date could refer to the branching out of Painted-Linear (continental) and Impressed-Cardium (maritime) Neolithic cultures in the Aegean or the Balcans.

Oldest evidence for cooking in pots comes from Libya

Quickies

Kambiz Karami at Anthropology.net (a most interesting blog to follow) mentioned this week that Libyan pottery remains, maybe as old as 10,000 years ago, have provided the oldest evidence of vegetable cooking of we know of, at least in pots (see below for the disclaimer). The remains indicate cooking of vegetables and meat and are associated to pictures of people gathering plants, as well as grinding stones (hand mills) with remains of such provisions.


Ref. Nature Plants.


Oddly enough, just two days later, he contradicted himself, mentioning that the charred remains of nuts and seeds from Palestine, dated from 780,000 years ago, actually provide the oldest evidence of vegetable cooking, even if it's clearly a more primitive way of cuisine and not yet at all the "refined" stew of ancient Libyans, which won them three stars in the Paleo-Michelin Guide for Nomads and five pitchforks in Popular Mesolithic Cuisine

Ref. PNAS.



Update (Jan 4): origin of Libyan and West Asian pottery could be Sudan

Jm8 mentions it in the comments, referencing to Anthromadness. I would need more data to judge (the ref. paper is behind paywall) but  it does sounds as probably correct to me, being Sudan/Nubia one of the earliest Mesolithic areas in the Western half of the Old World, one that is way too often and unfairly neglected but that definitely influenced the Levant prior to the development of Neolithic proper (what should explain a lot of things both linguistic and genetic).

Ancient aboriginal DNA from El Hierro (Canary Islands)

The island of El Hierro (lit. The Iron) is one of the westernmost of the Canary Islands. I have never visited but it seems to be very beautiful, far enough from the Sahara to enjoy a warm yet humid climate. It wasn't far enough to remain uninhabited however and now we get to know something more about its original dwellers, generally known as Guanches (although technically this name only applied to the inhabitants of La Palma originally).

Alejandra C. Ordóñez et al., Genetic studies on the prehispanic population buried in Punta Azul cave (El Hierro, Canary Islands). Journal of Archaeological Science 2016. Pay per viewLINK [doi:10.1016/j.jas.2016.11.004]

Abstract

The aim of this study was to establish the genetic studies of the population from one of the most important known aboriginal funerary spaces of the island of El Hierro (Canary Islands), the Punta Azul cave, which harbors remains of 127 individuals. Sixty-one adult tibiae were examined, 32 left and 29 right. Radiocarbon dating yields an antiquity of 1015–1210 AD. We have obtained an overall success rate of 88.5% for the molecular sexing, and of 90.16% for the uniparental markers. Short tandem repeats (STR) profiles were also possible for 45.9% of the samples. This performance is a consequence of the good conservation of the bones in their archaeological context. The mtDNA composition of the sample is characterized by the complete fixation of the H1-16260 lineage. These results can be explained by a mixture of consecutive founding events, a bottleneck episode at the beginning of the colonization and/or as a consequence of genetic drift. Paternal lineages were also affected by these processes but in a less acute way. These differences lead us to propose social behaviors as an explanation for this difference. The maternal transmission of the lineages, mentioned in ethnohistorical sources of the Archipelago, could be an explanation. These results could be in agreement with endogamous practices, but the autosomal STR results indicate a relative high diversity. These results have allowed us to characterize the Punta Azul cave population and see the way in which geographical isolation, the process of adaptation and specific social behaviors affected the aboriginal population of the Island.

And now the interesting stuff, the findings:



As should be expected, the remote and rather small western island, which is the most direct threat to the security of the USA and the Western World in general because of the danger its volcano may slide into the Ocean and cause a huge tsunami of devastating consequences, something that no nuclear arsenal can do anything against, shows clear indication of very strong genetic drift relative to its relatives of the larger islands, caused either by founder effects and/or endogamous drift. Otherwise it is within the general patterns for the pre-colonial islanders. 

We see a lot of likely mtDNA H and certain Y-DNA R1b1a2. The Canary Islands were settled c. 1000 BCE (11,000 HE) by people arrived from what is now Morocco and the Western Sahara. They seem to retain a somewhat archaic genetic pool, relatively rich in Europe-related genetic elements, not so abundant at all today in Northwest Africa anymore, and by this I mean of course very especially Y-DNA haplogroups I and R1b. While we can still find some R1b in NW Africa, haplogroup I is almost impossible to find nowadays, yet it was present in the Canary Islands prior to European conquest and nearly disappeared afterwards (so it's definitely not a colonial input, accidentally misidentified, not at all). 

See also: Leherensuge: Ancient Guanche Y-DNA.

Iberomaurusian ancient mtDNA

This is an issue that has lingered for a long time in the online anthropology circles. Once upon a time (2005) there was online a presentation in which a good deal of mitochondrial DNA (HVS-I) sequences from the key Iberomaurusian (or Oranian) culture site of Taforalt (North Morocco) were (not too formally) published. Eventually this presentation became almost impossible to find... however now Rym Kefi (the original author if I remember correctly) and colleagues have got back to resurrect that important data set from oblivion, plus sequences from Afalou cave as well.

Rym Kefi et al., On the origin of Iberomaurusians: new data based on ancient mitochondrial DNA and phylogenetic analysis of Afalou and Taforalt populations. Forsenic Sciences Research 2016. Freely available at the time & space of writing thisLINK [doi:10.1080/24701394.2016.1258406]

Abstract

The Western North African population was characterized by the presence of Iberomaurusian civilization at the Epiplaeolithic period (around 20,000 years before present (YBP) to 10,000 YBP). The origin of this population is still not clear: they may come from Europe, Near East, sub-Saharan Africa or they could have evolved in situ in North Africa. With the aim to contribute to a better knowledge of the settlement of North Africa we analysed the mitochondrial DNA extracted from Iberomaurusian skeletons exhumed from the archaeological site of Afalou (AFA) (15,000–11,000 YBP) in Algeria and from the archaeological site of Taforalt (TAF) (23,000–10,800 YBP) in Morocco. Then, we carried out a phylogenetic analysis relating these Iberomaurusians to 61 current Mediterranean populations.

The genetic structure of TAF and AFA specimens contains only North African and Eurasian maternal lineages. These finding demonstrate the presence of these haplotypes in North Africa from at least 20,000 YBP. The very low contribution of a Sub-Saharan African haplotype in the Iberomaurusian samples is confirmed. We also highlighted the existence of genetic flows between Southern and Northern coast of the Mediterranean.

The bulk of the data is this (tables 1 and 2):



Notice that all sequences are "old style", i.e. HVS-I only, and that's why haplogroup assessment is not always 100% certain, with particular emphasis on the "CRS" sequences, which have been proven in some ancient cases to belong not to the modern normal (H1, rarely H2 o other H) but to a very rare modern haplotype within U*, AFAIK only preserved in Asturias but somewhat common in the Magdalenian of South Germany. 

In any case, that they produce 100% safe H1, H6, H14, etc. and, even more surprisingly, J and T2 variants, should make people think about the hidden Paleolithic mtDNA diversity in the wider Mediterranean area. And by this I do not just mean North Africa but also all Southern Europe, including many areas that can't be considered part of the Mediterranean basin, such as most of the crucial Franco-Cantabrian Region, the most densely populated province, by far, of post-LGM Upper Paleolithic Europe, source of several cultural waves (including the Solutrean one, almost certainly at the origin of Iberomaurusian), yet outrageously neglected by research.

Table 5 and other materials in the paper also deal with which modern populations appear closest to the Iberomaurusian ancient mtDNA pool and these are:
  1. Tuscans (0.00090)
  2. Catalans (0.00134)
  3. Galicians (0.00223)
  4. Sicilians (0.00377)
  5. El Alia (0.00699)
  6. Valencian (0.00787)
  7. Matmata (0.00788)
  8. Slougia (0.00831)
  9. Jerba Berbers (0.00934)
Figures in brackets are FST distances, the smaller the closer the match, statistically speaking. Populations in cursive are from Northwest Africa.

That is I'd say quite surprising because we tend to think of those near matches as quite impacted by Neolithic and post-Neolithic inflows, at least judging on other recent research. It seems that the debate on the origin of modern Europeans and North Africans refuses to come to a close, as different aspects of the evidence available may be somewhat contradictory. What do you make up of all this?

See also:


UPDATE: single marker inferred lineages (not always the haplogroup is reported correctly):

Down in the comments' section, Capra questions with good sense the certainty of inferred haplogroups. The most clear one is TafV27, claimed to be H6a1a8, which cannot actually be that (would need another HVS-I marker defining H6, which is missing), however this means that it must be HV0 and possibly V, a lineage that appears (per the aDNA literature) in the European Neolithic, already quite towards the West, out of nowhere, and that "nowhere" should not be West Asia, where it has never been sequenced, unlike K. 

I'm therefore reviewing here all the single-marker inferred haplogroups as carefully as possible, please double-check them and report if I seem to be committing any error:
  • AF22B - 16126C (reported as JT or H14b1) - JT(xJ,xT) or H14b1 indeed, notice that JT* was probably also one of the lineages described (also by the HVS-I method) for Nerja cave (Solutrean, same time frame), just across Alboran Sea (cf. Fernández-Domínguez 2005). Whether is one or the other or even something else, it's almost certain that the lineage was shared across the sea between Europe and Africa, what just makes total sense for this culture.
  • Taf55-IB - 16239T (reported as H1) - I actually get specific H1 variants (H1bf'bg'bh'ch specifically) or H17c. H sublineages in any case, unless it is an extinct or unreported R* lineage, most unlikely.
  • TafV27 - 16298C (reported as H6a1a8) - must be HV0, possibly even V, a distributed Euro-African lineage with three hotspots: Kabylia, Catalonia and Lappland. Per Caramelli 2003 and successor studies, this lineage was already present in Italy (Pagilicci cave) in the Gravettian era.
  • TafVIII - 16223T (reported as U4a2b) - It cannot be U4 at all because it lacks the HVS-I mutation 16356C. In fact the reverse 16223C mutation defines macro-haplogroup R, and I can't find any other matches within R, so it must be L3(xR), maybe N(xR) but maybe M or other L3. The possibilities are many, for example: N1, N2, N9, N11, etc. within N, a lot of possibilities within M, and also several within L3e'i'k'x(xL3x). The only thing we should be certain here is that it is not R and also not upstream of L3 (that's how good as it gets with HVS-I methodology, really). 
  • TafXXV3 - 16126C (reported as H14b1) - as with AF22B, it can be JT(xJ,xT) or H14b1 and again I must emphasize that there is an extremely good chance that this matrilineage had relatives in Iberia (Nerja) within the Solutrean culture.

In case you want to re-check, the best resource is of course PhyloTree.



IMPORTANT CAVEAT: the above update was done assuming they had fully sequenced the HVS-I, which is not that long, but it seems that in many cases (second column of the tables above) they have only sequenced up to the 16317 locus, what makes prediction of haplogroup even harder. That would explain their H6a1a8 prediction, although there's no way they can exclude the much more common HV0 (H6 is unheard of in North Africa). Thanks again to Capra for pointing that out.

Happy 12,017

Yeah, 12,017. Why not? And I do mean the year that begins today per the Gregorian Calendar.

This is a surprisingly well thought idea that some prehistorianists (i.e. those who like Prehistory, regardless of wage-earning profession) have proposed: to get rid of the clearly uncomfortable Christian Era, alias Roman Era, alias Common or Conventional Era (CE) by adding 10,000 years to it and roughly starting counting at Göbekli Tepe (approx. date, because it's impossible to pinpoint an exact date, but the same happens with the alleged birth of baby Jesus anyhow), without doubt the first "civilizational" type of monument ever built, incidentally getting rid of negative counting for at least the whole Holocene (a most convenient feature indeed). 

They propose to call it the "Human Era" (HE), although I'd rather think that the Human Era begins with humans and that would be c. 200,000 years ago for Homo sapiens and two million years ago for the overall Homo genus, Humankind generally speaking. So maybe it's better to call it the Monumental Era, the Megalithic (big stone) Era or just the Mega-Era, for short. It'd be ME in any case.

The proposal, as far as I can tell, was made by Kurzgesagt, one of the YouTube channels that provide a good mix of entertainment and information for people interested in history and prehistory, young and elderly alike:




And I like it quite a bit, of course. So maybe worth spreading around, don't you think? 

In any case, I wish you all a happy and productive new year, one in which things may hopefully change for the better and not for the worse, for a change. 

And, like in every New Year Day, the holiday where most work is made, because of that floating notion that you are supposed to made up for all the laziness and procrastination of the past year, I will now proceed to assault my quite fatty "to do" list, and tell you about things that you may or not know already but that I think are worth taking note of.

November 2, 2016

Main Neanderthal admixture episode was c. 100,000 years ago.


This is really nice to read, considering that the archaeological data strongly favors a single out-of-Africa migration around that date (c. 125 Ka to Arabia and Palestine, see this, this and this among others, c. 100 Ka to South and East Asia) and that my own genetic modeling on mitochondrial DNA also fits that chronology (unlike most "molecular clock" scholastic rantings that are sold as "scientific truth" with no substantive backing whatsoever).

Admittedly the paper is not new (was published in February) but you know I have been missing important stuff with my information-overload stress crisis, so I'm making up now. Thanks to Ryan for bringing this up.

Martin Kuhlwilm et al., Ancient gene flow from early modern humans into Eastern Neanderthals. Nature 2016. Pay per viewLINK [doi:10.1038/nature16544]

Abstract

It has been shown that Neanderthals contributed genetically to modern humans outside Africa 47,000–65,000 years ago. Here we analyse the genomes of a Neanderthal and a Denisovan from the Altai Mountains in Siberia together with the sequences of chromosome 21 of two Neanderthals from Spain and Croatia. We find that a population that diverged early from other modern humans in Africa contributed genetically to the ancestors of Neanderthals from the Altai Mountains roughly 100,000 years ago. By contrast, we do not detect such a genetic contribution in the Denisovan or the two European Neanderthals. We conclude that in addition to later interbreeding events, the ancestors of Neanderthals from the Altai Mountains and early modern humans met and interbred, possibly in the Near East, many thousands of years earlier than previously thought.

As the title and the abstract say, Homo sapiens migrants out of Africa (i.e. into Asia and only later into its periphery) genetically influenced the branch of Neanderthals represented by the Altai specimen, what we can consider "Asian Neanderthals" but not the branch represented by El Sidrón and Vindija ("European Neanderthals"). This happened some 100 Ka ago, coincident with the archaeologically demonstrated dates for the out-of-Africa migration for our species and also likely Neanderthal-Sapiens hybrid fossils like Skhul-5 (right -- notice its lack of chin, a key and universal trait of H. sapiens, which allows us to give up with heavy browridges and other facial armature and still retain a strong bite, among other Neanderthaloid features, however it has a rounded and elevated skullcap with a high, almost vertical, forehead, a clear Sapiens trait). 

The flow was in both directions. I do not have access to the paper itself but it is clear in the supplemental material (EDF-1). This hybridization event was distributed quite evenly among all "Greater Asians" or "non-Africans" in our species. The slightly lower score in French is surely caused by Neolithic admixture later on, bringing African-like genetics to Europe, which are absent in most of Asia, as well as in aboriginal Australasia and America. 

Another apparent highlight in this paper (EDF-7) is that a second Neanderthal population, belonging to what I called above "European Neanderthals" (but related only to El Sidrón and not to Vindija) seems to have starred a second hybridization event affecting mostly Eastern populations (Han Chinese and Papuans in this paper's dataset). This, if confirmed, is quite unexpected and would require some explanation of the kind: there was a "European Neanderthal" population somewhere in Asia in the early times of Homo sapiens colonization and they got again admixed but this time affecting the derived populations in an irregular way. These irregularities would eventually be "flattened", I guess, at regional levels but for then the West Eurasian founders were out of the way. 

A somewhat related recent paper, also mentioned by Ryan, is S. Sankararaman et al., The Combined Landscape of Denisovan and Neanderthal Ancestry in Present-Day Humans (Current Biology 2016), also pay-per-view, so judging on supplemental materials only. I must say I don't like this one that much but at least table S2 offers a summary of the state of the art of estimates of Neanderthal and "Denisovan" (H. heidelbergensis) admixture in a lot of populations (and not just three). It is apparent there that there is more Neanderthal admixture towards the East of Asia or "Greater Asia", what is very much counterintuitive and demands that a Neanderthal population (a "European Neanderthal" one per Kuhlwilm's data) existed somewhere towards the East of Asia, enabling for this secondary Neanderthal admixture event. 

Perplexing maybe but that's what the data says. I wish we could find and sequence some of those Eastern Neanderthals which are so far just a genetic ghost, with the only possible known paleontological evidence being the Narmada skullcap, which is admittedly very much Neanderthal-like but is not associated in any way to Neanderthals' typical industry: the Mousterian, which has never been found east of Iran nor south of Mongolia. 

Some have argued that the Zhirendong jaw, one of the key evidences for c. 100 Ka H. sapiens settlement of much of Asia, is a hybrid one, with clear H. sapiens traits (among others it has a chin) but also maybe "archaic" traits (among others its chin is rather small). If so, then we may be at the same time in this case before evidence of both the early migration of our species, Homo sapiens, to East Asia (or SE Asia, as it's quite to the south of China) and the second admixture event with Neanderthals, with those ghostly Oriental Neanderthals, related to El Sidrón ones in the Far West, quite paradoxically, that we have yet to properly identify.

October 28, 2016

The destiny of a cave lion: to serve as decoration

Quickies

Spanish researchers have concluded that a carpet or other comparable fur ornament (a tapestry?, a cape?) is why a late cave lion remains, the latest ones known in Iberia, were found in an otherwise human (Magdalenian) context in the cave of La Garma (Asturias, Spain): it was a fur, claws included, used as decoration of some sort.

Marian Cueto et al., Under the Skin of a Lion: Unique Evidence of Upper Paleolithic Exploitation and Use of Cave Lion (Panthera spelaea) from the Lower Gallery of La Garma (Spain). PLoS ONE, 2016. Open accessLINK [doi:10.1371/journal.pone.0163591]

Abstract

Pleistocene skinning and exploitation of carnivore furs have been previously inferred from archaeological evidence. Nevertheless, the evidence of skinning and fur processing tends to be weak and the interpretations are not strongly sustained by the archaeological record. In the present paper, we analyze unique evidence of patterned anthropic modification and skeletal representation of fossil remains of cave lion (Panthera spelaea) from the Lower Gallery of La Garma (Cantabria, Spain). This site is one of the few that provides Pleistocene examples of lion exploitation by humans. Our archaeozoological study suggests that lion-specialized pelt exploitation and use might have been related to ritual activities during the Middle Magdalenian period (ca. 14800 cal BC). Moreover, the specimens also represent the southernmost European and the latest evidence of cave lion exploitation in Iberia. Therefore, the study seeks to provide alternative explanations for lion extinction in Eurasia and argues for a role of hunting as a factor to take into account.

Fig 4. Cave lion distal phalanxes from the Lower Gallery of La Garma.
Note that only eight of nine specimens are depicted in the figure.

Above: the claws that are the only remnants found of said lion, whose cut marks are fully coincident with skinning techniques used in more recent times with similar decorative purpose. They are believed to be all anterior claws and that one is missing therefore. That is why they imagine the fur to have been cut with an aesthetic interest, because the hind claws would not be visible if the fur was, for example, hang on the wall, so they were probably cut off.

Whether hunting of lions by humans was a decisive, contributing or negligible factor in cave lion extinction remains unclear.

October 27, 2016

Mitochondrial DNA from post-Neolithic Santimamiñe (Basque Country)

Four human remains dated to the Bronze Age were sequenced for mitochondrial DNA in Santimamiñe cave (Kortezubi, Biscay, Basque Country), along with single instances from the Neolithic, Chalcolithic and Roman period.

J.C. López Quintana et al., NUEVOS DATOS SOBRE LA SECUENCIA DE USO SEPULCRAL DE LA CUEVA DE SANTIMAMIÑE (KORTEZUBI, BIZKAIA). Arqueología y Prehistoria del Interior Peninsular (ARPI), 2016. Freely accessible (PDF) → LINK [no DOI]


The mtDNA study is not "brand new" but a synthesis of a previous doctoral thesis and advance publications:

Un primer avance de este estudio fue publicado en la monografía de las campañas de 2004 a 2006 de Santimamiñe (Cardoso et al. 2011), incluyendo el conjunto completo en la Tesis Doctoral de L. Palencia Madrid (Palencia 2015).

So we are talking of relatively old data, that has partly remained within the (sometimes absurdly greedy and anti-social) academic circles until now. The relative antiquity of the DNA study is important when assessing it, because genetic analysis is evolving very fast and, in most cases in the rather closed and under-budgeted Spanish universitary circles, they tend to do things "the old way", so we are almost certainly dealing here with HVS-I sequencing, something that is not explicit in the paper (I'm searching for Leire Palencia's thesis to make sure but no luck until now). 

If I am correct in this (and I should be), then we must understand that it is impossible in many cases to determine the exact haplogroup in the crucial R0 upper tier haplogroup, which includes HV and the extremely common H. Lacking the original HVS-I sequences by the moment, I can't but take the authors labels at face value but I must warn here that where it reads "R0" it is almost certainly H (HV0 or V are easy to recognize with this method, as is R0a) and where it reads "H1" it is probably H1 but not 100% certain. 

For more details see the relevant PhyloTree page, where the HVS-I markers are the last bloc in blue, beginning always with the sequence "16" (the other markers in blue of lower numerical value are HVS-II, more rarely used, and the ones in black are the coding region markers, which are in this case fundamental for proper assignment).


The mtDNA haplogroups (as reported) are:

  • Neolithic:
    • U5a2a (S2011-M2, c. 5100 BCE)
  • Chalcolithic:
    •  T2b (S-1, c. 2000 BCE)
  • Bronze Age:
    • U5b (S2011-M1 c. 1700 BCE) 
    • H1 (S2011-M4, c. 1700 BCE)
    • R0 (S2011-M6, c. 1500 BCE)
    • U3a (S2011-M3 c. 1300 BCE)
  • Roman period: 
    • R0 (S2011-M5, c. 300 CE)


Interpretation attempts


It's difficult to extract conclusions from them but they should be compared with other sequences from the area, for which I recommend my 2013 synthesis. In general, treat "R0" as meaning "H", even if I chose to use a different color (magenta instead of red) for exactitude. 

In order to aid that analysis, I reproduce here my 2013 graphic:


We cannot compare the single Neolithic and Roman Era individuals but we can compare the Satimamiñe Chalcolithic+Bronze group of five sequences with the peripheral Chalcolithic large dataset of De La Rúa:

  1. R*+H (very similar):
    1. Peripheral "Basque" Chalcolithic: ~40%
    2. Santimamiñe Chalcolithic+Bronze: 40% 
    3. Santimamiñe Bronze only: 50%
  2. U(xK) (very different):
    1. Peripheral "Basque" Chalcolithic: ~15%
    2. Santimamiñe Chalcolithic+Bronze: 40%
    3. Santimamiñe Bronze only: 50%
  3. Other lineages (all them of certain Neolithic immigrant origin, very different too):
    1. Peripheral "Basque" Chalcolithic: ~45%
    2. Santimamiñe Chalcolithic+Bronze: 20%
    3. Santimamiñe Bronze only: 0%

However one of the U(xK) lineages in Santimamiñe is U3, which is also quite certain to be of Neolithic immigrant origin, and one is an important figure when n=5 so we can also see it this way:
  1. Paleolithic lineages:
    1. Peripheral "Basque" Chalcolithic: ~55%
    2. Santimamiñe Chalcolithic+Bronze: 60%
    3. Santimamiñe Bronze only: 75%
  2. Neolithic lineages:
    1. Peripheral "Basque" Chalcolithic:  ~45%
    2. Santimamiñe Chalcolithic+Bronze: 40%
    3. Santimamiñe Bronze only: 25%

The comparison of #1 with #2 is much more similar. This could be important, because Santimamiñe is not anymore a "peripheral" site, as are those from De La Rúa's dataset, but a rather central one with a extremely long and uninterrupted Paleolithic sequence, dating to Neanderthal-made Chatelperronian culture. It is still a single site with a small number of samples but it does provide a counterpoint that, in one approach could produce similar results. 

But, surprisingly, when we consider a distinct Bronze Age category, comparing not anymore with #2 but with #3 everything changes, suggesting a totally different interpretation of the available dataset, in which, the "Chalcolithic interlude" (if real at all, more data is needed) would be reversed quickly with the onset of the Bronze Age. 

I am sorry but I cannot lean for either interpretation: the data is just not extensive enough to allow for conclusions. I am tempted to support the continuity hypothesis, allowing only for lesser changes to happen, and keep the Chalcolithic dataset under a big question mark, but the question mark is admittedly a bit smaller now: something in terms demographic may have happened in the Chalcolithic period and may have been reversed in the Bronze Age. But "may" is not "for sure", we need more data points.

Feel free to discuss in good mood, as always.

Thanks for the heads up to Jean Lohizun (again).

October 22, 2016

The 300 (improved) genomes project

I must make mention here of this study, which seems an attempt to improve the available datasets of global human genetics, particularly the widely used 1000 Genomes Project. It has some less striking but still interesting highlights.

Swapan Mallick et al., The Simons Genome Diversity Project: 300 genomes from 142 diverse populations. Nature, 2016. Pay per viewLINK [doi:10.1038/nature18964]

Abstract

Here we report the Simons Genome Diversity Project data set: high quality genomes from 300 individuals from 142 diverse populations. These genomes include at least 5.8 million base pairs that are not present in the human reference genome. Our analysis reveals key features of the landscape of human genome variation, including that the rate of accumulation of mutations has accelerated by about 5% in non-Africans compared to Africans since divergence. We show that the ancestors of some pairs of present-day human populations were substantially separated by 100,000 years ago, well before the archaeologically attested onset of behavioural modernity. We also demonstrate that indigenous Australians, New Guineans and Andamanese do not derive substantial ancestry from an early dispersal of modern humans; instead, their modern human ancestry is consistent with coming from the same source as that of other non-Africans.

The genomes and some other information seem to be available in their dedicated webpage.

One of the highlights is explicit in the abstract: the single African origin of Homo sapiens and the single out-of-Africa migration episode are confirmed. I didn't have any doubt but there have been occasional speculations, based on nothing worth considering, on the conjecture of more than one migration out of Africa before the Holocene, maybe affecting Australasian peoples. Not at all: it's all based on mere misunderstanding on how "racial" traits evolved, those remote isolated peoples basically allow us for a glimpse on the plausible phenotypes of the early Eurasian migrants, which were probably quite dark in skin pigmentation and most often had thinly curled hair like that of most Africans. In fact, I have argued on occasion that it is very possible that straight hair and its less extreme variants, wavy and widely curly hair, are Neanderthal genetic and phenotype influences, positively selected for some unclear reason, and not part of our African Homo sapiens heritage. 

The other highlight that I appreciate is that they find some errors in the 1000 Genomes Project, particularly affecting Australasians, Andamanese and some Africans (quite extreme among the Khoisan particularly). This is very apparent in this map and might explain some misleading and often puzzling conclusions made by some researchers, academic or amateur alike:


Otherwise I do not find their reconstructions of the paleo-history of Humankind, based only on autosomal DNA (not the best tool for such deep incursions, really), too helpful. But the most important thing is the existence and availability of a new, allegedly improved, global dataset.

October 21, 2016

Wisent co-existed with true bison already in the Paleolithic

A fascinating story this one indeed: the European bison or wisent has some ancestry related to the cow, evident in its mitochondrial DNA. This was already known but what wasn't known is that this distinct "hybrid" species of bison dated to the Upper Paleolithic. Thanks to the excellent records of anonymous prehistorical biologists who recorded them in Southwestern European rock art with great detail and naturalism, modern researchers have realized that the wisent, with its bovid heritage, existed already in the Upper Paleolithic. Ancient DNA recovery has now confirmed the artist's impression.

Julien Soubrier et al. Early cave art and ancient DNA record the origin of European bison. Nature communications, 2016. Open access → LINK [doi:10.1038/ncomms13158]

Abstract

The two living species of bison (European and American) are among the few terrestrial megafauna to have survived the late Pleistocene extinctions. Despite the extensive bovid fossil record in Eurasia, the evolutionary history of the European bison (or wisent, Bison bonasus) before the Holocene (< 11.7 thousand years ago (kya)) remains a mystery. We use complete ancient mitochondrial genomes and genome-wide nuclear DNA surveys to reveal that the wisent is the product of hybridization between the extinct steppe bison (Bison priscus) and ancestors of modern cattle (aurochs, Bos primigenius) before 120 kya, and contains up to 10% aurochs genomic ancestry. Although undetected within the fossil record, ancestors of the wisent have alternated ecological dominance with steppe bison in association with major environmental shifts since at least 55 kya. Early cave artists recorded distinct morphological forms consistent with these replacement events, around the Last Glacial Maximum (LGM, ∼21–18 kya).


The depictions of both types of bison are rather distinct but it seems nobody had noticed the difference until now, as the researchers explain in this article.

Fig. 1 - (a) Reproduction from Lascaux cave (France), from the Solutrean or early Magdalenian period (20,000 kya—picture adapted from ref. 53). (b) Reproduction from the Pergouset cave (France), from the Magdalenian period (<17,000 kya—picture adapted from ref. 54).

The ancient wisents sequenced now carry a distinct mtDNA haplogroup, called "clade X", which is sister to that of modern wisents (all descending from just 12 survivors). This wisent macro-haplogroup forms a clade with that of bovine cattle (cows of all sorts, both taurine and indicine) but they are joined only at the root, suggesting that the hybridization event that created the wisents as distinct species is very old, just a bit more recent than the divergence of cow and bison.

Fig. 2 - (a) Phylogenetic tree inferred from bovine mitochondrial control region sequences, showing the new clade of bison individuals. The positions of the newly sequenced individuals are marked in red for CladeX. (b) Bovine phylogeny estimated from whole-mitochondrial genome sequences, showing strong support for the grouping of wisent and CladeX with cattle (cow) and zebu. For both trees (a,b) numbers above branches represent the posterior probabilities from Bayesian inference, numbers below branches represent approximate likelihood ratio test support values from maximum-likelihood analysis and scale bars represent nucleotide substitutions per site from the Bayesian analysis. (c) Maximum-clade-credibility tree of CladeX and wisent estimated using Bayesian analysis and calibrated with radiocarbon dates associated with the sequenced bones. Dates of samples older than 50 kyr were estimated in the phylogenetic reconstruction. (d) Map showing all sampling locations, using the same colour code (red for CladeX, orange for wisent and blue for steppe bison).

So it is not random auroch hybridization but a very specific and very ancient episode of admixture between the ancestors of bisons and cows.

The two species appear to have distinct ecological niches:

The detailed records of the southern Ural sites allow the timing of the population replacements between steppe bison and wisent to be correlated with major palaeoenvironmental shifts, revealing that the wisent was associated with colder, more tundra-like landscapes and absence of a warm summer.

This pattern seems to correspond with the periods in which the two species are portrayed in rock art, as two of the researchers explain in this video (third part):




Post-statement: I must say that, on second thought, I'm not really convinced by the claim of wisent corresponding to colder periods. In fig. 1 above it is apparent that it is the steppe bison which corresponds to the last glacial maximum (LGM) in Southwestern Europe and not the wisent, which only shows up after the end of this coldest period. 

I wonder if the researchers are explaining themselves well enough on this aspect or if it is a case of wishful thinking, maybe caused by different conditions in SW Europe (where the rock art is) and the Southern Urals (where most of the archaeogenetic and paleontological data comes from). 

At the very least, judging on fig. 1, it would be the steppe bison the one corresponding with the coldest spell and the wisent the one corresponding to more temperate conditions. Can someone explain me what is going on here?

Armintxe: new rock art site discovered in the Basque Country

A week ago a new rock art site was revealed to exist right in the town of Lekeitio (Biscay). The art, estimated to be from some 14,000 years ago (Magdalenian culture), is made up of several groups of engraved animals: bisons, horses, goats and deers. The cave is not far from other known sites like Lumentxa, Atxurra and Santa Catalina.

Video of the cave and art[es]:




More information:
Arkeobasque
Pileta de Prehistoria[es] (has several videos and news from several sources, quite extensive)