Finally some improved knowledge of haplogroup R1a1 (Y-DNA)

Haplogroup R1a, most of which is R1a1, dominant in Northern South Asia and Eastern Europe, as well as in much of Central Asia, has been giving headaches to population geneticists, academic and amateur alike, because key markers were not identified, making most of the haplogroup look like an amorphous goo, the same in India as in Europe. It seems that this may change now:

Horolma Pamjav et al., Brief communication: New Y-chromosome binary markers improve phylogenetic resolution within haplogroup R1a1. AJPA 2012. Pay per view ··> LINK [10.1002/ajpa.22167]

Abstract

Haplogroup R1a1-M198 is a major clade of Y chromosomal haplogroups which is distributed all across Eurasia. To this date, many efforts have been made to identify large SNP-based subgroups and migration patterns of this haplogroup. The origin and spread of R1a1 chromosomes in Eurasia has, however, remained unknown due to the lack of downstream SNPs within the R1a1 haplogroup. Since the discovery of R1a1-M458, this is the first scientific attempt to divide haplogroup R1a1-M198 into multiple SNP-based sub-haplogroups. We have genotyped 217 R1a1-M198 samples from seven different population groups at M458, as well as the Z280 and Z93 SNPs recently identified from the “1000 Genomes Project”.

The two additional binary markers present an effective tool because now more than 98% of the samples analyzed assign to one of the three sub-haplogroups. R1a1-M458 and R1a1-Z280 were typical for the Hungarian population groups, whereas R1a1-Z93 was typical for Malaysian Indians and the Hungarian Roma. Inner and Central Asia is an overlap zone for the R1a1-Z280 and R1a1-Z93 lineages. This pattern implies that an early differentiation zone of R1a1-M198 conceivably occurred somewhere within the Eurasian Steppes or the Middle East and Caucasus region as they lie between South Asia and Eastern Europe. The detection of the Z93 paternal genetic imprint in the Hungarian Roma gene pool is consistent with South Asian ancestry and amends the view that H1a-M82 is their only discernible paternal lineage of Indian heritage.

Not having access to the paper right now, I can't say much more but I believe that the abstract alone is very informative already.

Distribution of R1a per Underhill 2010

 

Update:

Fig. 1 - MJ trees
(click to expand)

A reader already sent me a copy of the paper and I think that it has two aspects:

On one side the paper effectively detects these markers and study them, as well as R-M458 in Hungarians and related ethnic groups (Csangos, Szeklers, Hungarian Roma), as well as in Malaysian Indians, Uzbeks and Mongols. This part is informative, even if the selected Asian populations may not be the best choice (Mongols are low in R1a and so are Tamils who make up the bulk of Malaysian Indians).

On the other side, the authors attempt to read too much, not just on these haplogroups but specially on molecular-clock-o-logic estimates, (based on the Zhivotovsky mutation rate, now considered obsolete even by molecular clock enthusiasts). A corrected age estimate would be roughly doubly old[ref 1, ref 2] and that means that neither the Kurgan expansion nor the Neolithic one could account for its arrival to Europe.

Even using Underhill age estimates, they'd imply at least LGM dates for the arrival to Europe after the due correction. Their own dates, after due x2 correction, give Late Upper Paleolithic dates for the haplogroups researched here. 

Also the authors insist on arguing against a South Asian origin of R1a1 (Underhill 2010) on what sound like weak and fallacious arguments:

Previous publications have pointed out that regions of highest haplogroup frequencies do not always indicate the territory of origin (Cinnioglu et al., 2004) and high STR diversity may not be exclusively an indicator of in-situ diversification but could also be the consequence of repeated gene flow from different sources (Zerjal et al., 2002; Sharma et al., 2009).

Basically they are nagging: "Underhill could hypothetically be wrong in his conclusions but we have no evidence whatsoever that he is - just saying". 

The real reason is that they seem to hope to find a more westerly origin for the lineage and attribute it again to Indoeuropean expansions, in line with classic speculations for which the high South Asian STR diversity levels are a big problem. However it is most unlikely that a bunch of horse-riding nomads could so radically alter the genetic landscape of the whole subcontinent, more so when its agriculture was already fully developed, sustaining no doubt high densities. 

But notwithstanding all those highly questionable opinions, the discovery of new haplogroups adding to our comprehension of this major lineage is a great advance.


Update: 

It seems that some of the data exposed in this paper was already floating around in some circles because ISOGG already includes the "new" haplogroups in its phylogenetic synthesis. Most interestingly the two "European" clades (along with a third one, whose geography I ignore so far) make up a larger haplogroup (R1a1a1b1a - S198/Z282), which is "brother" of the "Asian" one (R1a1a1b2 - S202/Z93).

As I was just commenting elsewhere the key to the origins of R1a is not so much in these low level haplogroups but in the higher "asterisk" paragroup, which (from memory) used to be concentrated in Pakistan and nearby areas of India, etc.

But once reached the level of R1a1a1b1 (S339/Z283), this lineage seems to have split in two: one which we can describe as "European" and another which we can describe as "Indian".

The European half is treated in this paper as two of its subclades only and separately, what may be confuse. Hence I am adding here a synthesis of the current ISOGG phylogeny of R1a, with some annotations, for easier reference:

• R1a* ··> Iran, Persian Gulf, Turkey
• R1a1  (L120/M516, L122/M448, M459, Page65.2/SRY1532.2/SRY10831.2)
• R1a1* ··> Iran, Caucasus, Greece, Scandinavia
• R1a1a (L168, L449, M17, M198, M512, M514, M515)
•  R1a1a* ··> where? (not clear)
  
•  R1a1a1 (M417, Page7)
• R1a1a1* ··> where?
  
• R1a1a1a (L664/S298)  ··> where?
• R1a1a1b (S224/Z645, S441/Z647)
• R1a1a1b* ··> where?
• R1a1a1b1 (S339/Z283)
• R1a1a1b1* ··> where?
• R1a1a1b1a (S198/Z282)
• R1a1a1b1a*
• R1a1a1b1a1 (M458) ··> Central & East Europe
• R1a1a1b1a2 (S204/Z91, S466/Z280) ··> Europe, Central Asia
• R1a1a1b1a3 (S221/Z284, S443/Z289) ··> where?
• R1a1a1b2  (S202/Z93) ··> India, Central Asia

All the data on the geography of top level "asterisk" paragroups is from Underhill 2010, already mentioned above. It suggest a West Asian origin for R1a overall and spread to West and East since the R1a1a level or lower.

I used colors to emphasize the clades discussed here (purple for the larger haplogroup, blue for the European-leaning clade and red for the Indian-leaning one).

Clades in cursive are "proposed", not yet consolidated.

Bonze Age city discovered in Northern China

Shimao was protected by a thick wall (source)

The site of Shimao in Northern Shaanxi was already known but new measures indicate it covers more than 4 km² being surrounded by a thick wall, what makes it a city without almost any possible debate.

I could only find so much information on the finding but the date provided (4000 years ago) would place it between the Late Neolithic culture of Longshan and the Early Bronze one of Erlitou, which is typically identified with the Xia dynasty. [But see update].

Sources in English: Mole, China.org. In Spanish: Spanish People.


Update: Va_Highlander has been looking up articles in Chinese (see comments) and it seems that the site is identified as having a long sequence from mid-Longshan to Erlitou (or Xia Dynasty).

The site is located on the Northern edge of the Loess Plateau, some 20 km away from the Yellow River. 

References in Chinese language: Guancha, Smwhys and Sina.com.

Bronze swords

Update (Feb 28 2014): "sacrificial altar" found in Shimao → People Daily.

Emotional care or neglect of young children decisive for brain size, intelligence

An image says more than a thousand words. And in this case the image is a brain scan... or rather two side by side:

Both brains belong to 3-years-old children

... the child with the shrunken brain was neglected and abused by its mother, and the child with the larger and more fully developed brain was raised in a loving, supportive home and was looked after by its mother...

This is not just about IQ or head size, which may vary at least largely because of this type of environmental causes, but about everything in life, including emotional and social intelligence and the general ability to carry on with a normal, well integrated life (or become human waste). 

The first years of life are critical for all our development and parental love, very specially that of our mothers, is probably more important than almost anything else.

Source: Medical Daily.

The genetic and phenotype complexity of the Oceanic language area

In this entry, rather than discussing Polynesians alone, which seem to be just the tip of the Eastern Austronesian iceberg, I'll try to understand here the complexity of speakers of Oceanic languages, the main native language family of Island Oceania. 

Oceanic is a branch of Austronesian but for the purposes of this entry we will only mention other Austronesian peoples/languages tangentially. The focus is Oceanic because we can't understand the parts without the whole here most probably. 

Linguistics

Oceanic languages are scattered as follows:

  Admiralties and Yapese

  St Matthias

  Western Oceanic and Meso-Melanesian (two distinct sub-families)

  Temotu

  Southeast Solomons

  Southern Oceanic

  Micronesian

  Fijian–Polynesian

Black enclosed zones are pockets of languages from other families.

(CC by kwami)

It is certainly interesting that Micronesian and Fijian-Polynesian seem to be particularly related among them. Instead the Western Oceanic and Admiralty subfamilies (both from the islands near Papua) seem to have separated early on or diverged farther for whatever other reasons (stronger substrate influence for example).

Prehistory

Lapita pot from Tonga (source)

As I cited recently, Polynesians seem to have spread from Society Islands in the 1190-1290 CE window. The genesis of the Micronesian family is not well understood... but the overall genesis of Oceanic languages seems to be at the Lapita culture, which spread through Island Melanesia (excluding Papua) and some nearby islands (notably Tonga and Samoa - also Marquesas c. 300 CE(ref)).

Early Lapita culture is dated to c. 1350-750 BCE, while a Late phase is dated to c. 250 BCE, spreading to the Solomon Islands, which show no indications of the earlier period (Ricaut 2010, fig. 2).

So a simplified chronology for Oceanic expansion would be

1. Lapita culture from near Melanesia to Vanuatu and Kanaky (New Caledonia), then to:
1. Fiji, Samoa and Tonga since c. 900 BCE
2. Solomon Is. c. 250 BCE
2. Arrival to Society Islands (Tahiti, etc.) c. 300-800 CE from maybe Samoa.
3. Main Polynesian expansion to the farthest islands (Hawaii, Rapa Nui, Aotearoa-NZ) c. 1200 CE from Society Is.

Phenotype ('race')

A classical and unavoidable element in the ethnographic division of the region is phenotype, appearance (i.e. 'race'). Since the first European arrival to the area the division between black Melanesians and white Polynesians (very relative as we will see now) has been part of all our conceptualizations of the region. 

Conscious of that and wanting to get a better impression I collected from the Internet what I estimate may be representative faces from the Oceanic linguistic zone and nearby areas (other Austronesians and Melanesians) and put them on a map:

Click to expand

A relatively homogeneous Polynesian phenotype can be identified and one can imagine that it stems from the area of Samoa-Tonga, considering the previous prehistorical review. But otherwise the diversity, gradations and abundance of local uniqueness seems quite impressive.

Based on other cases, one would imagine also that phenotype differences would be coincidental with genetic ones. However this is not too easy to discern, partly because Polynesians have strong founder effects that blur the matter, partly because there is no obvious strict dividing line between the various phenotypes and partly because of the insistence of some in considering Lapita as a Polynesian phenomenon, when it is obviously an Oceanic one, including and emphasizing the Melanesian side of the diverse Oceanic landscape, of which the Polynesian-Micronesian branch is just one element (famous and extended but not the core). 

Genetics

The main Y-DNA lineage among Polynesians is C2a1 (P33), not found outside Polynesia senso stricto but reaching there frequencies of 63-90% (excepted Tonga where it's only 33%). This is a clear founder effect in this population.

C subclades in SE Asia and Oceania
(from Karafet 2010, annotated with ISOGG nomenclature)

C2a1 is clearly derived from a Melanesian superset C2a (M208) still found as C2a(xC2a1) at low frequencies in Samoa (8%) and Tahiti (4%) but also in Vanuatu (2%) and coastal Papua (13%). C2a establishes a probably genetic link of Polynesians with Lapita culture and Melanesian peoples in general.

An earlier pylogenetic stage is C2 (M38), which is probably in the region since the very first colonization process some 50 thousand years ago (or maybe even earlier). C2(xC2a) is most common in Wallacea (East Indonesia, East Timor), where it reaches maybe figures of 33% on average. It is however also found in highland Papua (13%) and Vanuatu (20%) but as it is most doubtful that C2a evolved as recently as Lapita times, we should really focus on C2a as such rather than the wider C2, which only seems to confuse the matter.

The lack of C2(xC2a) in most of the Oceanic languages' area clearly indicates that the expansion (and subsequent founder effects) did not begin in Wallacea but in  Melanesia, at least in what regards to C sublineages.

The other major Polynesian haplogroup is O3a2 (P201), which would seem to have originated in Philippines and maybe arrived there via Micronesia:

O3 subclades in SE Asia and Oceania
(from Karafet 2010, annotated with ISOGG nomenclature)

Melanesian populations also sport some lineages that are not common among other Oceanic-speaker peoples, notably K, M and S. However they are irregularly shared with Wallacea (Eastern Indonesia, East Timor). Like C2 these lineages coalesced in the region soon after colonization by Homo sapiens.

In the motherly side of things genetic, the absolutely dominant mtDNA lineage among Polynesians (the so-called Polynesian motif) is B4a1a1, which ultimately stems from East or rather SE Asia. However it probably arrived to the region (again) via Melanesia, albeit maybe somewhat tangentially.

From Friedlander 2007 (fig. 4)

Spatial frequency distribution of haplogroup B4a* and B4a1a1 in Island Southeast Asia and the western Pacific, created using the Kriging algorithm of the Surfer package of haplogroups. Figure 4b presents the detailed distribution for Northern Island Melanesia. Data details are provided in table S3.

The matrilineal Polynesian motif does offer a possible pattern of settlement, maybe related specifically to Late Lapita, that could allow us to understand the possible origin of the phenotype differences between Melanesians and Polynesians, as could do the Y-DNA lineage O3a2. However there are lots of remnants of quite strictly Melanesian Early Lapita, as is evident by the (Y-DNA) C2a lineages retained so strongly among Polynesians within their own founder effects, whose importance we cannot afford to dismiss.

Other mtDNA lineages like Q1 or M27 are of relevance in Melanesian populations. Q1 did make its way into some Polynesian populations but as minority lineage only.


Update (Oct 31):

Terry in the comments sections grunts a lot but now and then provides useful complementary data, for example this Y-DNA map of the region from Kayser 2006:

Kayser 2006 - fig. 1
Frequency distribution of (A, B) NRY and (C, D) mtDNA haplogroups found in Polynesia with a genetic origin in (A, C) Asia or (B, D) Melanesia.

As is apparent since Kayser's publication (if not before), the Melanesian patrilineages are much more common (actually dominant) among Polynesians than the matrilineages from the same origin, what is attributable to a founder effect related to the Lapita culture.

Another interesting reference is this Y-DNA map of Papua (New Guinea) and some nearby islands (from Mona 2007):

Mona 2007 FIG. 2.—Y-chromosome haplogroups and their frequencies in populations from the Bird’s Head region and elsewhere in New Guinea. Data from other populations of New Guinea were used from previous studies (Kayser et al. 2003, 2006). Size of the pie charts is according to sample size of the groups. Abbreviations are as in supplementary table S1, Supplementary Material online.

Both maps and/or the data in the relevant papers provide key information on possible origins for the C2a-M208 patrilineal founder effect, so important in general in the Oceanic peoples and specially the Polynesian branch. The exact origin cannot be pinpointed without further research (or maybe not at all) but it's clear that C2a-M208 only exists from Papua (New Guinea) to the East, so it must have a Melanesian origin be it Papuan or from the nearby islands.

Bibliography

• François-Xavier Ricaut et al., Ancient Solomon Islands mtDNA: assessing Holocene settlement and the impact of European contact. Journal of Archaeological Science, 2010 ··> LINK (PDF).
• Jonathan S. Friedlaender et al., Melanesian mtDNA Complexity. PLoS ONE, 2007 ··> LINK (open access).
• Tatiana Karafet et al., Major East-West Division Underlies Y Chromosome Stratification Across Indonesia. MBE 2010 ··> LINK (free access).
• Michael Knapp et al., Complete mitochondrial DNA genome sequences from the first New Zealanders. PNAS 2012 ··> LINK (open access).
• Manfred Kayser et al., Melanesian and Asian Origins of Polynesians: mtDNA and Y Chromosome Gradients Across the Pacific. MBE 2006 ··> LINK (open access).
• Stephano Mona et al., Patterns of Y-Chromosome Diversity Intersect with the Trans-New Guinea Hypothesis. MBE 2007 ··> LINK (free access).

_________________________________________________________________________________
Note: updates after first posted version in maroon color.

IL-4 genetic combo protects Indian hunter-gatherers from Malaria

Or, more precisely, protects many of those who have it in diverse populations but it is most concentrated among hunter-gatherers of the so-called Ancestral Tribal Populations (ATP).

Aditya Nath Jha et al., IL-4 Haplotype -590T, -34T and Intron-3 VNTR R2 Is Associated with Reduced Malaria Risk among Ancestral Indian Tribal Populations. PLoS ONE 2012. Open access ··> LINK [doi:10.1371/journal.pone.0048136]

Abstract

Background

Interleukin 4 (IL-4) is an anti-inflammatory cytokine, which regulates balance between TH1 and TH2 immune response, immunoglobulin class switching and humoral immunity. Polymorphisms in this gene have been reported to affect the risk of infectious and autoimmune diseases.

Methods

We have analyzed three regulatory IL-4 polymorphisms; -590C>T, -34C>T and 70 bp intron-3 VNTR, in 4216 individuals; including: (1) 430 ethnically matched case-control groups (173 severe malaria, 101 mild malaria and 156 asymptomatic); (2) 3452 individuals from 76 linguistically and geographically distinct endogamous populations of India, and (3) 334 individuals with different ancestry from outside India (84 Brazilian, 104 Syrian, and 146 Vietnamese).

Results

The -590T, -34T and intron-3 VNTR R2 alleles were found to be associated with reduced malaria risk (P<0.001 for -590C>T and -34C>T, and P = 0.003 for VNTR). These three alleles were in strong LD (r²>0.75) and the TTR2 (-590T, -34T and intron-3 VNTR R2) haplotype appeared to be a susceptibility factor for malaria (P = 0.009, OR = 0.552, 95% CI = 0.356 –0.854). Allele and genotype frequencies differ significantly between caste, nomadic, tribe and ancestral tribal populations (ATP). The distribution of protective haplotype TTR2 was found to be significant (χ²₃ = 182.95, p-value <0.001), which is highest in ATP (40.5%); intermediate in tribes (33%); and lowest in caste (17.8%) and nomadic (21.6%).

Conclusions

Our study suggests that the IL-4 polymorphisms regulate host susceptibility to malaria and disease progression. TTR2 haplotype, which gives protection against malaria, is high among ATPs. Since they inhabited in isolation and mainly practice hunter-gatherer lifestyles and exposed to various parasites, IL-4 TTR2 haplotype might be under positive selection.

The protection is not absolute but it holds very strong statistical significance for the R2-R3 heterozygous combo, as shown in fig. 1:

Figure 1. Distribution of IL-4 intron-3 VNTR polymorphism.

A and B: genotype and allelic distribution between malaria case control groups, respectively; C and D: genotype and allelic distribution among caste, nomadic, tribe and ancestral tribe, respectively.

Combo that is most common (near-optimal distribution) among the ATPs. The correlation holds for the four linguistic families with variations being more a matter of individual ATP tribes: from 35% among the AoNaga (TB, Nagaland) to 67% among the Baiga (IE, Madhya Pradesh) or 63% among the Onge (Jarawa-Onge, Andaman Is.)

 

See also:

• The other red cell disease that protects against the other malaria
• Malaria and sickle cell anemia do not correlate well in Asia

Variation in human (modern and archaic) and chimpanzee lipoprotein APOE

This new study has some interest in understanding some details, of metabolic relevance, of the genetics of humans and our closest relatives:

Annick McIntosh et al., The Apolipoprotein E (APOE) Gene Appears Functionally Monomorphic in Chimpanzees (Pan troglodytes). PLoS ONE 2012. Open access ··> LINK [doi:10.1371/journal.pone.0047760]

Abstract

Background

The human apolipoprotein E (APOE) gene is polymorphic, with three primary alleles (E2, E3, E4) that differ at two key non-synonymous sites. These alleles are functionally different in how they bind to lipoproteins, and this genetic variation is associated with phenotypic variation for several medical traits, including cholesterol levels, cardiovascular health, Alzheimer’s disease risk, and longevity. The relative frequencies of these alleles vary across human populations, and the evolution and maintenance of this diversity is much debated. Previous studies comparing human and chimpanzee APOE sequences found that the chimpanzee sequence is most similar to the human E4 allele, although the resulting chimpanzee protein might function like the protein coded for by the human E3 allele. However, these studies have used sequence data from a single chimpanzee and do not consider whether chimpanzees, like humans, show intra-specific and subspecific variation at this locus.

Methodology and Principal Findings

To examine potential intraspecific variation, we sequenced the APOE gene of 32 chimpanzees. This sample included 20 captive individuals representing the western subspecies (P. troglodytes verus) and 12 wild individuals representing the eastern subspecies (P. t. schweinfurthii). Variation in our resulting sequences was limited to one non-coding, intronic SNP, which showed fixed differences between the two subspecies. We also compared APOE sequences for all available ape genera and fossil hominins. The bonobo APOE protein is identical to that of the chimpanzee, and the Denisovan APOE exhibits all four human-specific, non-synonymous changes and appears functionally similar to the human E4 allele.

Conclusions

We found no coding variation within and between chimpanzee populations, suggesting that the maintenance of functionally diverse APOE polymorphisms is a unique feature of human evolution.

The relevant details are all in table 1:

Table 1. Variation at key APOE functional sites in Homo and Pan.

There is uncertainty about the correctness of the only known Neanderthal triplet.

Even if E4 seems to be the ancestral type, E3 is the most common allele in our species, ranging from 50% in most populations to as much as 90% among some tribes.

East Asian oaks in the Ice Age

It may sound botanically erudite but it is also of great relevance in order to better understand the ecology and geography of people living in East Asia in the Upper Paleolithic. Hence worth mentioning here.

Dongmei Chen et al., Phylogeography of Quercus variabilis Based on Chloroplast DNA Sequence in East Asia: Multiple Glacial Refugia and Mainland-Migrated Island Populations. PLoS ONE 2012. Open access ··> LINK [doi:10.1371/journal.pone.0047268]

Abstract

The biogeographical relationships between far-separated populations, in particular, those in the mainland and islands, remain unclear for widespread species in eastern Asia where the current distribution of plants was greatly influenced by the Quaternary climate. Deciduous Oriental oak (Quercus variabilis) is one of the most widely distributed species in eastern Asia. In this study, leaf material of 528 Q. variabilis trees from 50 populations across the whole distribution (Mainland China, Korea Peninsular as well as Japan, Zhoushan and Taiwan Islands) was collected, and three cpDNA intergenic spacer fragments were sequenced using universal primers. A total of 26 haplotypes were detected, and it showed a weak phylogeographical structure in eastern Asia populations at species level, however, in the central-eastern region of Mainland China, the populations had more haplotypes than those in other regions, with a significant phylogeographical structure (NST = 0.751 > GST = 0.690, P < 0.05). Q. variabilis displayed high interpopulation and low intrapopulation genetic diversity across the distribution range. Both unimodal mismatch distribution and significant negative Fu’s F_S indicated a demographic expansion of Q. variabilis populations in East Asia. A fossil calibrated phylogenetic tree showed a rapid speciation during Pleistocene, with a population augment occurred in Middle Pleistocene. Both diversity patterns and ecological niche modelling indicated there could be multiple glacial refugia and possible bottleneck or founder effects occurred in the southern Japan. We dated major spatial expansion of Q. variabilis population in eastern Asia to the last glacial cycle(s), a period with sea-level fluctuations and land bridges in East China Sea as possible dispersal corridors. This study showed that geographical heterogeneity combined with climate and sea-level changes have shaped the genetic structure of this wide-ranging tree species in East Asia.

 
Maybe most interesting of all is this map: 

Figure 5. Ecological niche modelling.

Predicted distribution probability (in logistic value) is shown in each 2.5 arc-min pixel, based on the palaeodistribution modelling at present (0BP) (a) and at the last glacial maximum (LGM) (21KaBP) (b). The distribution of river systems on the exposed East China Sea during the LGM was drawn from Shota et al. (2012). Occurrence records of Q. variabilis at present are also plotted as black points in the maps.

Much more data for those interested in the genetic details can be found in the paper. 

Propose alternative model for Neanderthal admixture in non-Africans

I must say I am totally  skeptic but just for the record:

Armando G. M. Neves & Mauricio Serva, Extremely Rare Interbreeding Events Can Explain Neanderthal DNA in Living Humans. PLoS ONE. Open Access ··> LINK [doi:10.1371/journal.pone.0047076]

Abstract

Considering the recent experimental discovery of Green et al that present-day non-Africans have 1 to of their nuclear DNA of Neanderthal origin, we propose here a model which is able to quantify the genetic interbreeding between two subpopulations with equal fitness, living in the same geographic region. The model consists of a solvable system of deterministic ordinary differential equations containing as a stochastic ingredient a realization of the neutral Wright-Fisher process. By simulating the stochastic part of the model we are able to apply it to the interbreeding ofthe African ancestors of Eurasians and Middle Eastern Neanderthal subpopulations and estimate the only parameter of the model, which is the number of individuals per generation exchanged between subpopulations. Our results indicate that the amount of Neanderthal DNA in living non-Africans can be explained with maximum probability by the exchange of a single pair of individuals between the subpopulations at each 77 generations, but larger exchange frequencies are also allowed with sizeable probability. The results are compatible with a long coexistence time of 130,000 years, a total interbreeding population of order 10⁴ individuals, and with all living humans being descendants of Africans both for mitochondrial DNA and Y chromosome.

Not only the discourse of the authors is strangely ideological (strange insistence in resuscitating the dead horse of multirregionalism and denying the rather unquestionable out-of-Africa model at least in name) but also they come to admit that:

The decision of which model correctly describes the origin of Homo sapiens is obscured by the intricacies of the statistical methods proposed for evaluating the models themselves.

And so they proceed to create their own intricate model and even more intricate interpretation.

Sincerely, their model of continuous admixture would normally cause West Eurasians (at least) to have much more Neanderthal introgression than Papuans, whose ancestors have been far away from West Eurasia (the former Neanderlands) since c. 80 Ka most probably (archaeological evidence of African-related techno-cultures in India, Petraglia 2007), while West Eurasian ancestors would have been in intense contact with Neanderthals all or most of that time until the effective Neanderthal extinction of c. 35,000 years ago. 

There's no convoluted model nor mathematical fallacy that can circumvent that: anything but a single admixture episode or process early on in the colonization of Eurasia by Homo sapiens makes no sense.

Megalithic burial found in Minorca

The naveta (Binibèquer, Sant Lluís) is one of a few in all the island, belonging to the Bronze Age (Naviform I period: c. 1750-1000 BCE). This kind of tombs are exclusive of Minorca.

The new discovery is yet to be researched or even cleared

The famous and well preserved Naveta des Tudons (for comparison)
CC BY-ND 2.0

Source: Menorca Info[es] (via Pileta).

Ancient Maori mtDNA

Terry points me to this paper:

Michael Knapp et al., Complete mitochondrial DNA genome sequences from the first New Zealanders. PNAS 2012. Open access ··> LINK [doi:10.1073/pnas.1209896109 ]

Abstract

The dispersal of modern humans across the globe began ∼65,000 y ago when people first left Africa and culminated with the settlement of East Polynesia, which occurred in the last 1,000 y. With the arrival of Polynesian canoes only 750 y ago, Aotearoa/New Zealand became the last major landmass to be permanently settled by humans. We present here complete mitochondrial genome sequences of the likely founding population of Aotearoa/New Zealand recovered from the archaeological site of Wairau Bar. These data represent complete mitochondrial genome sequences from ancient Polynesian voyagers and provide insights into the genetic diversity of human populations in the Pacific at the time of the settlement of East Polynesia.

The authors sequenced ancient mtDNA from the pre-colonial period from a museum material being returned for proper reburial. The remains belong to a population from Wairau Bar from the 13th-14th centuries, which were looted by British museums in the mid 20th century. 

Of the 19 individuals researched, only four provided valid sequences. All four Three were within the so-called Polynesian motif or haplogroup B4a1a1a, the other was Q1, a lineage of Melanesian origin also found, albeit rarely, among other Polynesians. All modern studied Maoris are B4a1a1a but Q1 is known to exist among Cook Islanders, for example. (Corrected: Q1 is mentioned but in the context of other Polynesian populations, not New Zealand).

Interestingly the authors also explain that the colonization of Eastern Polynesia was performed not in a series of small randomized migrations but in a single expansive wave in the 12th-13th centuries CE, what explains the relative homogeneity of their customs and languages. 

A recent reevaluation of the dates for the colonization of East Polynesia suggests that, contrary to earlier studies positing a relatively long (2,000 y) chronology for the region, the settlement of most of East Polynesia occurred rapidly, in the period from A.D. ∼1190–1290 (22). The authors determined that the expansion event occurred from the Society Islands, which were only settled 70–265 y previously. This rapid and recent expansion event, they argue, explains the “remarkable uniformity of East Polynesian culture, human biology and language” (22).

The cited reference (22) is:

Wilmshurst JM, Hunt TL, Lipo CP, Anderson AJ (2011) High-precision radiocarbon dating shows recent and rapid initial human colonization of East Polynesia. Proc Natl Acad Sci USA 108(5):1815–1820.

Blood groups A and B inherited from simian ancestors

A new study has found that blood group A and B alleles have been stable (albeit in likely dynamic equilibrium) in the primate family since... always.

Laure Ségurel et al., The ABO blood group is a trans-species polymorphism in primates. PNAS 2012. Pay per view (6 months embargo) ··> LINK [doi:10.1073/pnas.1210603109]

Abstract

The ABO histo-blood group, the critical determinant of transfusion incompatibility, was the first genetic polymorphism discovered in humans. Remarkably, ABO antigens are also polymorphic in many other primates, with the same two amino acid changes responsible for A and B specificity in all species sequenced to date. Whether this recurrence of A and B antigens is the result of an ancient polymorphism maintained across species or due to numerous, more recent instances of convergent evolution has been debated for decades, with a current consensus in support of convergent evolution. We show instead that genetic variation data in humans and gibbons as well as in Old World monkeys are inconsistent with a model of convergent evolution and support the hypothesis of an ancient, multiallelic polymorphism of which some alleles are shared by descent among species. These results demonstrate that the A and B blood groups result from a trans-species polymorphism among distantly related species and has remained under balancing selection for tens of millions of years—to date, the only such example in hominoids and Old World monkeys outside of the major histocompatibility complex.

Razib has some more details on the matter (being PPV, I haven't read it). Still he wonders what kind of disease or otherwise evolutionary pressure may have been so virulent as to keep the whole order of primates (or at the very least all simians) on our toes all these millions of years.

The answer may well be known already: it seems that type A blood protects against the plague, while type B protects against smallpox, both great historical killers of those without enough defenses. However they may favor other less important health problems like blood clots or cancer, enough to exert a mild pressure in favor of a return to the basic type zero ("O"), which would have evolved by loss of function once and again. 

Whatever the case I find fascinating that these immune mechanisms may be so extremely persistent and I wonder if the bacterian mechanisms they confront may be more generic than just an specific disease.

See also: maps of distribution of major blood types.


Update: a pre-print copy of the paper is available at arXiv.

Alert: destruction of 8000 year-old engravings in Morocco by Fundamentalists - government denies

The Amazigh League for Human Rights denounced the destruction of several Neolithic engravings in Toubkal National Park, south of Marakesh. Among the damaged art is said to be a depiction of the Sun as a god. They date from c. 6000 BCE.

Source and more details: BBC (h/t Stone Pages' Archaeonews).

The damaged relic (source)

Update: the Government of Morocco denies the claim with strange wording

The Moroccan authorities have denied the claim of a vandalism against a solar engraving attributed to Fundamentalists. According to an AFP report:

"This kind of incident, contrary to our values, cannot take place in Morocco," it said, adding that an investigation carried out with local and regional authorities had showed that the claims were unfounded.

But such sites "can suffer, like elsewhere, the effects of natural and even human degradation, sometimes through vandalism and trafficking."

The wording is at the very least strange: the logic does not seem sound (can't happen because of our values) and the suggestion of other reasons for the same vandalism are at the very least suspicious. 

My reading is that the Moroccan Ministry of Culture wishes to deny all kind of militant Salafist activism but that, subtly, acknowledges the destruction, attributing it to mystery causes (either erosion or mindless vandalism) rather than Fundamentalism. 

Not too credible. 


Update (Oct 25):

Dalouh (see comments) has been gathering some more info on the matter from Arabic language sources in Facebook and it would seem that the locals chased out the fundamentalist vandals preventing greater damage, still:

Above: damage stone, below: original

Periodization of Saharan rock art

Marnie has a most interesting blogpost today on the periodization of Saharan rock art, specifically at Tadrart Acacus site in SW Lybia. It is not a well known matter so I am recycling her entry and the materials at Amis de l'Art Rupestre Saharien[fr/en/de/it] to make a quick visual note here on the matter.

Periodization dates are based on description at UNESCO site but need not to be correct for all pieces or not all authors need to agree to them. Here I follow that lead after some thoughts just because of its simplicity, which may well be misleading. It should only be taken as a very basic introductory note, nothing else.

Naturalistic or bubaline phase (14-10,000 BP):

··> more info at AARS.

Reminds a bit of rock art from Qurta (Nubia, Egypt).

Round head phase (10-6,000 BP):

··> more info at AARS.

Bovidian or Pastoral phase (6000-3500 BP):

··> more info at AARS.

As Marnie mentions, this phase would be approximately after the date of earliest clear evidence for milking in Africa, which is of c. 7000 BP.

Caballine phase (3500-2000 BP):

··> more info at AARS.

This would be soon after the date of arrival of the Hyksos to Egypt, who brought the chariot from Asia.

Cameline phase (since 2000 BP):

··> more info at AARS.

Dromedaries were probably introduced in Egypt (and the rest of Africa) with the Persian invasion c. 500 BCE.

Large Neolithic-Chalcolithic settlement found in Antequera (Andalusia)

Burial in flexed position

Pileta de Prehistoria reports[es] on the discovery of a large settlement occupying some 150 hectares in Arroyo Saladillo (Antequera) from the transitional Neolithic-Chalcolithic period (centuries around 3000 BCE). 

The site was previously known but the archaeological research prior to the public works on the high speed rail branch Antequera-Granada have evidenced that it was much larger than believed, occupying an almost circular area, delimited with a ditch or moat, with a diameter of 1.4 Km (less than one mile across), what results in an occupation of 150 Ha., of which only a fraction has been excavated so far. 

In this research zone of 700x40m. as many as 139 silos for cereal storage have been documented, some with carbonized remains, others (four) recycled as tombs, other four newly excavated burials and also four burials of megalithic type (dolmen).

Among the materials recovered are loom weights, tuyeres (sign of incipient metallurgy), marble and shell bracelets, three idols made in shale, pottery decorated with red ochre (a material also used in burials) and imported double edged axes. 

Economically speaking, agriculture, pastoralism, hunting and fishing all seem to have been important but maybe with some dominance of pastoralism (it is a mountain area).

New mtDNA age estimation paper claims post-LGM expansion dates for most relevant lineages

In Europe as in Africa and Native America.

You know that I'm very much refractory to molecular-clock-o-logy because it implies many a priori speculations and assumptions that probably make the results to be wrong and yet these results are presented as if they were the genetic equivalent of the proverbial "rocket science", when they are nothing but educated guesses, often contradicting each other.

Still I think that this paper is worth mentioning for two reasons:

1. It gives age estimates that are clearly pre-Neolithic for most lineages, rebuking certain fanatic school that pretends to impose their clearly unfounded ideas of mass demographic replacement in the Neolithic and in a single direction, with a simple pattern. It is always good to have that kind of counter-arguments at hand.
2. The paper is freely available (open access) in spite of being published by Nature (in an open access  dedicated magazine titled Scientific Reports).

Hong-Xang Zhieng et al., MtDNA analysis of global populations support that major population expansions began before Neolithic Time. Scientific Reports (Nature) 2012. Open access ··> LINK [doi:10.1038/srep00745]

Abstract

Agriculture resulted in extensive population growths and human activities. However, whether major human expansions started after Neolithic Time still remained controversial. With the benefit of 1000 Genome Project, we were able to analyze a total of 910 samples from 11 populations in Africa, Europe and Americas. From these random samples, we identified the expansion lineages and reconstructed the historical demographic variations. In all the three continents, we found that most major lineage expansions (11 out of 15 star lineages in Africa, all autochthonous lineages in Europe and America) coalesced before the first appearance of agriculture. Furthermore, major population expansions were estimated after Last Glacial Maximum but before Neolithic Time, also corresponding to the result of major lineage expansions. Considering results in current and previous study, global mtDNA evidence showed that rising temperature after Last Glacial Maximum offered amiable environments and might be the most important factor for prehistorical human expansions.

Importantly, these age estimates must be considered as minimal ages (everything else assumed correct and equal) because the mutation rate used in at least some of the calibrations (Soares' rates) is clearly too fast, with even Dienekes (a former hardcore defender of very short chronologies and hyper-fast mutation rates) admitting to it as of late.

I quote from Dienekes:

Soares et al. were cautious, and they assumed an earlier Human-Chimp split than had been favored until then. However, a new paper by Langergraber et al. have used direct observation of the autosomal mutation rate and of ape generation lengths to argue for an even earlier Human-Chimp split: at least 7-8 million years ago, and as many as 13 million.

Which  is something I am quite glad that people has begun realizing because I was saying that more or less, in many different ways, since 2008 (refs.: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, etc.) And it was not just me because I was mostly reflecting what many scholars were finding here and there, publishing and seldom being listened to.

So these post-LGM dates are at best minimal dates, most probably requiring corrections that range between +15% and +85% (avg. +50%) per the Langergraber figures.

So for example, the authors estimate a 10-18 Ka window for the main expansions in Africa and Europe, that could well be a 15-27 Ka window in fact (max. 10-33 Ka.)

Figure 4: European expansion lineages from median-joining network
Blue, GBR; purple, FIN; yellow, CEU; cyan, TSI; green, IBS.

However mtDNA specifically has other major issues, absent in nuclear DNA (autosomes or Y chromosome): that the mutations happen so spaced in time for the whole mitochondrial DNA chain, which is very short, that the main factor is not the molecular tic-tac but population dynamics.

I should write more extensively on this matter but D. Pierron already did for me in 2011 (discussed here).

As I understand this problem of extremely unequal mtDNA lines, these irregularities are mostly caused by relatively large populations in which mutational change is effectively stopped by mere drift. As most women in the population experience no mutation in their mtDNA, the mutants have all the tickets to see their novel, derived, lineages drifted out by their relatives with a conservative one.

So in my understanding mtDNA "clock" must only be counted (if at all) from the root and not, as is usual, from the ends. This is a total game changer because counting from the root, H must be slightlty older than U, while counting from the ends that is impossible.

I never count mtDNA from the ends even if I know that most geneticists and aficionados do because I find such a procedure totally thoughtless, a mechanical imitation of a method that works for longer DNA chains which accumulate mutations in every generation, quite unlike mtDNA, which is much more stable.

En fin, the paper provides us with another opportunity to reconsider the highly speculative but incredibly popular field of molecular-clock-o-logy. It also provides some nice MJ networks of many haplogroups, which speak on their own, one of which (Europe), I used to illustrate this entry.

Epigenetics and IQ variability

A new study on monozygotic (identical) twins with clear IQ differences finds that epigenetic methylation of certain genes may be the cause:

Chih-Chieh Yu, Genome-Wide DNA Methylation and Gene Expression Analyses of Monozygotic Twins Discordant for Intelligence Levels. PLoS ONE, 2012. Open access ··> LINK [doi:10.1371/journal.pone.0047081]

Abstract

Human intelligence, as measured by intelligence quotient (IQ) tests, demonstrates one of the highest heritabilities among human quantitative traits. Nevertheless, studies to identify quantitative trait loci responsible for intelligence face challenges because of the small effect sizes of individual genes. Phenotypically discordant monozygotic (MZ) twins provide a feasible way to minimize the effects of irrelevant genetic and environmental factors, and should yield more interpretable results by finding epigenetic or gene expression differences between twins. Here we conducted array-based genome-wide DNA methylation and gene expression analyses using 17 pairs of healthy MZ twins discordant intelligently. ARHGAP18, related to Rho GTPase, was identified in pair-wise methylation status analysis and validated via direct bisulfite sequencing and quantitative RT-PCR. To perform expression profile analysis, gene set enrichment analysis (GSEA) between the groups of twins with higher IQ and their co-twins revealed up-regulated expression of several ribosome-related genes and DNA replication-related genes in the group with higher IQ. To focus more on individual pairs, we conducted pair-wise GSEA and leading edge analysis, which indicated up-regulated expression of several ion channel-related genes in twins with lower IQ. Our findings implied that these groups of genes may be related to IQ and should shed light on the mechanism underlying human intelligence.

The list of genes with a detectable effect is as follows:

Table 2. List of genes having the same tendency of expression level in most twin pairs.

It's worth noticing that a recent study (Chabris 2012) reviewing the literature found that most or maybe even all alleged genetic influences in intelligence are probably false positives (discussed here). Therefore is probable that many (most?, all?) differences in intelligence are caused by environmental influences, often manifested in epigenetic modifications like the ones detected in this study.