Tag Archives: DNA study

Eurasian Y chromosome R1b in Africa.

Human Y chromosome haplogroup R-V88: a paternal genetic record of early mid Holocene trans-Saharan connections and the spread of Chadic languages

Fulvio Cruciani et al.

Abstract

Although human Y chromosomes belonging to haplogroup R1b are quite rare in Africa, being found mainly in Asia and Europe, a group of chromosomes within the paragroup R-P25* are found concentrated in the central-western part of the African continent, where they can be detected at frequencies as high as 95%. Phylogenetic evidence and coalescence time estimates suggest that R-P25* chromosomes (or their phylogenetic ancestor) may have been carried to Africa by an Asia-to-Africa back migration in prehistoric times. Here, we describe six new mutations that define the relationships among the African R-P25* Y chromosomes and between these African chromosomes and earlier reported R-P25 Eurasian sub-lineages. The incorporation of these new mutations into a phylogeny of the R1b haplogroup led to the identification of a new clade (R1b1a or R-V88) encompassing all the African R-P25* and about half of the few European/west Asian R-P25* chromosomes. A worldwide phylogeographic analysis of the R1b haplogroup provided strong support to the Asia-to-Africa back-migration hypothesis. The analysis of the distribution of the R-V88 haplogroup in >1800 males from 69 African populations revealed a striking genetic contiguity between the Chadic-speaking peoples from the central Sahel and several other Afroasiatic-speaking groups from North Africa. The R-V88 coalescence time was estimated at 9200–5600 kya, in the early mid Holocene. We suggest that R-V88 is a paternal genetic record of the proposed mid-Holocene migration of proto-Chadic Afroasiatic speakers through the Central Sahara into the Lake Chad Basin, and geomorphological evidence is consistent with this view.

I haven’t had a look at the full text for this yet, but relevant to this is the mt DNA study of Chadic speakers which showed a passage from East Africa (somewhere to the West of the Nile in the Sudan is my guess, it’s the only place the v88 and L3f3 would meet up).

 A date ~8,000 YBP was estimated for the L3f3 sub-haplogroup, which is in good agreement with the supposed migration of Chadic speaking pastoralists and their linguistic differentiation from other Afro-Asiatic groups of East Africa.

Which isn’t inconsistent with the date for V88 proposed at 9,200-5,600 years, and is also a very close match for the arrival of the Neolithic in Africa.

 Just a brief  note on the mt DNA  study: the only Afro-Asiatic speaking group that the Chadic speakers plot closely to is Cushitic, which will probably make Blench happy, as he claims Chadic speakers are a split-off from Cushitic speaking pastoralists. It’s fairly obvious that the male line of Chadic speakers followed a path into Africa via the Sinai, then down the West bank of the Nile and then struck out West to Lake Chad, acquiring wives as they went. The only issue is the exact date. Holocene or Neolithic? Whatever the exact date, this brings the argument for an Asian origin for Afro-Asiatic out again, as (from the DNA here) the odds are 50% that it followed the male line in from Asia. I would like to comment that Chadic has cognates for sheep and goats that look like they share a root with Cushitic and Egyptian, which would at least date proto Chadic to the Neolithic, making the mt DNA date of 8,000 more likely to be close to the actual date for V88 to enter Africa.

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The trans-Saharan slave trade – clues from interpolation analyses and high-resolution characterization of mitochondrial DNA lineages

The trans-Saharan slave trade – clues from interpolation analyses and high-resolution characterization of mitochondrial DNA lineages

Background: A proportion of ¼ to ½ of North African female pool is made of typical sub- Saharan lineages, in higher frequencies as geographic proximity to sub-Saharan Africa increases. The Sahara was a strong geographical barrier against gene flow, at least since 5,000  years ago, when desertification affected a larger region, but the Arab trans-Saharan slave trade could have facilitate enormously this migration of lineages. Till now, the genetic consequences of these forced trans-Saharan movements of people have not been ascertained.

Results: The distribution of the main L haplogroups in North Africa clearly reflects the known trans-Saharan slave routes: West is dominated by L1b, L2b, L2c, L2d, L3b and L3d; the Center by L3e and some L3f and L3w; the East by L0a, L3h, L3i, L3x and, in common with the Center, L3f and L3w; while, L2a is almost everywhere. Ages for the haplogroups observed in both sides of the Saharan desert testify the recent origin (holocenic) of these haplogroups in sub-Saharan Africa, claiming a recent introduction in North Africa, further strengthened by the no detection of local expansions.

Conclusions: The interpolation analyses and complete sequencing of present mtDNA sub-Saharan lineages observed in North Africa support the genetic impact of recent trans-Saharan migrations, namely the slave trade initiated by the Arab conquest of North Africa in the seventh century. Sub-Saharan people did not leave traces in the North African maternal gene pool from the time of its settlement, some 40,000 years ago.

I haven’t read the whole paper through yet, but just from reading the bit I put in bold.. I’m sure that a paper on ancient Guanche mtDNA showed an L haplotype or two present which meant they had to be present a few thousand years ago during the colonisation of the Canary islands.

 The majority of lineages (93%) were from West Eurasian origin, being the rest (7%) from sub-Saharan African ascription

And a very ancient age for L6 crossing over into Spain (about 20 kya) from another paper. So I’m going to state emphatically this can’t be correct. Not to mention that the ceramic using Saharan Negroid ’roundhead’ population reached as far as the Acacus mountains (about 10,500 bp) and would have had some contact/gene flow with the coastal Capsians (who were  a near Eastern /Mechtoid mixed people from the cranial studies I’ve seen and the expansion dates of Y chr J1 and H mtDNA). Although  the majority of the L haplotypes in North Africa are due to the slave trade, they can’t ALL be.
Edit:

I read through this this morning. The most interesting bits of the whole pdf for me were…

Clearly, the main component of the West Eurasian lineages was made of possible Iberian
expanded lineages following the post-glacial climate improvement: H1 (12.35%), V (9.88%)
and U5b (1.23%).

I’d debate the 14k age for this given in the paper… but they had to have arrived before the Taforalt people died as the H, HV /V turns up in those 12k old samples..

A few L3 sequences observed in North Africa have older co-ancestry with other sub-Saharan
regions, but as this occurs in the rarer haplogroups (almost restricted to East Africa), most
probably the scenario will change as these become better characterized. This is the case for
one L3x2 sequence observed in Algeria, which shares an older most recent common ancestor
with two Ethiopian, one Israeli and one Kuwait, at 33,165 ± 4,499 years ago, but one
Ethiopian and the Israeli and Kuwait sequences share a younger ancestor at 19,012 ± 4,200.
Also, one Egyptian L3f2b sequence shares an ancestor with a Chadic one at around 24,809 ±
5,935 years ago
. For L3h1a2 haplogroup, one Egyptian and one Lebanese sequences share a
coalescence age of 26,281 ± 6,139 years old. And for L3h1b, with an age of 36,827 ± 3,772
years
, one of the North African sequences (one Tunisian and one Moroccan) has a most recent
common ancestor of 14,766 ± 4,448 years old with a sequence from Guinea Bissau.

I’ve been looking for mtDNA that could have accompanied the M78 out of Africa (arriving in the near east and NW Africa about 22k ago). While M1 obviously fits that date, it’s nice to see that some of the L3 dates aren’t incompatible with the m78;  being found in Natufian areas of Israel and Lebanon. The Israel/Kuwait/Ethiopian L3 may be a back-migrating L haplotype, not incompatible with the return of M1 and U, or another haplotype caught up in the Lower Nubian expansion and fanned out into the same areas as the m78/M1.

So far, the two only complete published samples belonging to haplogroup L3k have a North
African origin, one from Libya and one from Tunisia. This haplogroup has a coalescent age of
around 29,251 ± 6,524 years old

Who/where did that come from?

But the most useful thing in the whole paper are the maps, which give a quick over view of L distribution in Africa. I’ve reworked this one in colour, as the original is a bit hard to make out in places.

One of the interesting patterns I noticed was the (quite possibly superficial) relation to the expansion of non-L haplotypes and L3h in E/SE Africa. Also the hotspot for L3h in Northern Sudan, makes me wonder if it may not have been a travelling companion to the non-African mt DNA’s at some time. Unlike Maju, I’d say this looks like it has an origin on the Nile rather in Ethiopia, as it seems to have a relation to the expansion pattern of the M1/M1a/m78  from Lower Nubia/Egypt.

I’m going to have a dig to see what I can find on L3h now…

Mitochondrial DNA and Y-Chromosome Variation in the Caucasus

Mitochondrial DNA and Y-Chromosome Variation in the Caucasus

We have analyzed mtDNA HVI sequences and Y chromosome haplogroups based on 11 binary markers in 371 individuals, from 11 populations in the Caucasus and the neighbouring countries of Turkey and Iran. Y chromosome haplogroup diversity in the Caucasus was almost as high as in Central Asia and the Near East, and significantly higher than in Europe. More than 27% of the variance in Y-haplogroups can be attributed to differences between populations, whereas mtDNA showed much lower heterogeneity between populations (less then 5%), suggesting a strong influence of patrilocal social structure. Several groups from the highland region of the Caucasus exhibited low diversity and high differentiation for either or both genetic systems, reflecting enhanced genetic drift in these small, isolated populations. Overall, the Caucasus groups showed greater similarity with West Asian than with European groups for both genetic systems, although this similarity was much more pronounced for the Y chromosome than for mtDNA, suggesting that male-mediated migrations from West Asia have influenced the genetic structure of Caucasus populations.

An older paper, but one I hadn’t taken a look at.

Unfortunately there isn’t as much detail on the mt DNA.

From one long ago read text, I can remember that one North Caucasus late neolithic site had a tendency to have Mediterranean male crania with the more robust local females. This could support that  population movements into the area from the Iran/Turkey area (birthplace of the Neolithic) may have been male lead, which might give a clue as to how each the Caucasus population has such a heterogenous Y chromosome profile.

Tunisian and Moroccan Y Chromosomes

Y-chromosome markers distribution in Northern Africa: High-resolution SNP and STR analysis in Tunisia and Morocco populations

Valerio Onofria, Federica Alessandrinia, Chiara Turchia, Mauro Pesaresia and Adriano Tagliabracci, a,
Abstract
At the beginning of 2006 more than 301,000 immigrants resident in Italy resulted to come from Tunisia and Morocco, 66% of which are male subjects; in addition, it is estimated that some other thousand are clandestine. Our data show that there is an increasing involvement of Tunisian and Moroccan individuals in paternity testing and in individual identification cases. For these reasons, the aim of this work was to enrich forensic Y-chromosome databases with Northern Africa data to better know markers frequency and their distribution across these populations. 103 Tunisian and Moroccan healthy male donors were typed by 17 microsatellites extended haplotype and 41 Y-SNPs. A high-resolution level database was created, including both haplotype and haplogroup for each sample. This study confirmed that precious informations might come both from Y-SNPs haplogroup distribution besides Y-STRs data.

[morocco_tunisia.jpg]

After just re-reading the Guanche Y chr the total abscence of  ‘I’ across this part of N Africa is a mystery. How did it get to the Canaries when it skipped Morocco? Admittedly the sample size is a bit small. Maybe it got missed.

Guanche Y chromosomes

Hairy Harry, Mad Peter and Tiny Amon

Demographic history of Canary Islands male gene-pool: replacement of native lineages by European

Abstract
 The origin and prevalence of the prehispanic settlers of the Canary Islands has attracted great multidisciplinary interest. However, direct ancient DNA genetic studies on indigenous and historical 17th-18th century remains, using mitochondrial DNA as a female marker, have only recently been possible. In the present work, the analysis of Ychromosome polymorphisms in the same samples, has shed light on the way the European colonization affected male and female Canary Island indigenous genetic pools, from the conquest to present-day times.

Results
Autochthonous (E-M81) and prominent (E-M78 and J-M267) Berber Y-chromosome lineages were detected in the indigenous remains, confirming a North West African origin for their ancestors which confirms previous mitochondrial DNA results. However, in contrast with their female lineages, which have survived in the present-day population since the conquest with only a moderate decline, the male indigenous lineages have dropped constantly being substituted by European lineages. Male and  female sub-Saharan African genetic inputs were also detected in the Canary population, but their frequencies were higher during the 17th-18th centuries than today.

Conclusions
The European colonization of the Canary Islands introduced a strong sex-biased change in the indigenous population in such a way that indigenous female lineages survived in the extant population in a significantly higher proportion than their male counterparts.

Unashamedly nicked from Maju- but topped off with a genuine portrait of a Guanche male called Hairy Harry (centre) shown to me by Ricardo.

gydna

Interesting to see the J1, which a couple of studies have placed in North Africa from about 10k ago. A fair amount of other older Eurasian lines. I’ll have another read of this one later.

mtDNA diversity in Sudan (East Africa)

mtDNA diversity in Sudan (East Africa)

A major effort must be put in East and sub-Saharan African mtDNA diversity characterisation for the construction of an informative database. We contribute 102 new HVRI + HVRII Sudanese sequences. As expected this sample is highly diverse, mainly constituted of unique haplotypes (2.07% random match probability for HVRI alone), 72.5% of which belong to sub-Saharan haplogroups.

Somehow this slipped past me last year- I think because it came out in the school holidays. It’s a bit short on detail unfortunately. A bit like this blog entry.

Genetic variation of 15 autosomal STR loci in Upper (Southern) Egyptians

Genetic variation of 15 autosomal STR loci in Upper (Southern) Egyptians

Abstract
A sample of 265 unrelated individuals inhabiting five governorates in Upper (south) Egypt was collected with informed consent. The samples were amplified using the AmpFℓSTR®Identifiler™PCR Amplification Kit (containing 15 loci: D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818 and FGA), and genotyped subsequent to capillary electrophoresis. Statistical analysis of the generated data indicated neither departure from expectation of Hardy–Weinberg Equilibrium (HWE) in most of the tested loci nor dependence of alleles between loci. All tested loci were polymorphic; the most discriminating is D18S51 while the least is TPOX. The combined power of exclusion was 0.99999868 and the combined match probability was 1.93×10−18. The genetic diversity of the Upper Egyptians was compared with those of other populations at the local, regional and global levels.

Multi-dimensional scaling (MDS) based on pair-wise FST genetic distances of Upper Egyptian and other diverse global populations. OCE, Oceanian; ME, Middle Eastern; NAF, North African; EAS, East Asian; SSA, sub-Saharan African; UEGY, Upper Egyptian; SAS, South Asian; EUR, European. The figure shows that Oceania and American populations are very distant from Upper Egyptians (marked by a grey triangle) and other populations. The Upper Egyptian population is closer to the Middle Eastern, North African, South Asian and European populations than others.

Not a mega surprise that upper Egyptians grouped closer to north African and near Eastern rather than West African samples. It would have been nice to see Ethiopian samples too, for a better sense of perspective.