Sunday, February 7, 2010

Guardian: Men from Britain and Ireland are Descended Mostly from Ancient Farmers and the R1b Haplogroup is shared with Continental Europe & Chad

Most British men are descended from ancient farmers. Ian Sample, science correspondent for The Guardian. Sample writes:
"The first farmers to arrive in Britain outbred the native hunter-gatherer men and have left their mark in modern males' Y chromosome....

... more than 60% of British men, and nearly all of those in Ireland, can trace their Y chromosome back to the agricultural revolution....

The farmers' Y chromosome becomes more common in the west of England and reaches a national peak of 78% in Cornwall, scientists found.....

Men with surnames including Titchmarsh and Haythornthwaite are among the most likely to carry the farmers' Y chromosome, known as R1b1b2. The Y chromosome is passed down the male line only, from father to son.

Researchers led by Jobling collected DNA samples from more than 2,500 men across Europe. Around 80% of the men had the R1b1b2 type of Y chromosome, making it the most common lineage on the continent."
Haplogroup R1b (Y-DNA) has been described as follows in the Wikipedia:
"In human genetics, Haplogroup R1b is the most frequently occurring Y-chromosome haplogroup in Western Europe. R1b is also present at lower frequencies throughout Eastern Europe, Western Asia, Central Asia, and parts of North Africa. R1b is also very common amongst speakers of Chadic languages in Sub-Saharan Africa. [emphasis added]

Within Europe, which has been much studied, R1b's frequency is highest in the populations of Atlantic Europe and, due to European emigration, in North America, South America, and Australia. In Ireland and the Basque Country its frequency exceeds 90% and approaches 100% in Western Ireland. The incidence of R1b is 70% or more in parts of northern and western England, northern Spain, northern Portugal, western France, Wales, Scotland. R1b's incidence declines gradually with distance from these areas but it is still common across the central areas of Europe. For example, R1b is the most frequent haplogroup in Germany, but not in neighboring Poland."
The Chadic connection is intriguing and suggests to this author the possibility of an influx of European blood into this region through ancient seafarers - for the oldest boats found in Africa are in the Chad region.

It is hard to explain the high incidence of R1b among Chadic speakers by presuming a land route, along which there is no evidence of R1b migration.

We give little credence to the land route solution proposed recently in Viktor Černý et al., Migration of Chadic speaking pastoralists within Africa based on population structure of Chad Basin and phylogeography of mitochondrial L3f haplogroup, BMC Evolutionary Biology, 2009, 9:63 doi:10.1186/1471-2148-9-63, who write in their conclusion, based only on mitochondrial (mtDNA, female) rather than Y-haploptype (male) evidence, that:
"We provide genetic support for an Early Holocene migration within Africa. A high-resolution phylogeny of haplogroup L3f based on whole mitochondrial genome sequences shows several clades that are unevenly distributed throughout Africa and Near East. Specifically, clade L3f3 is geographically limited to the Chad Basin where it reaches high frequencies especially in Chadic-speaking groups while almost absent in Niger-Congo and Nilo- Saharan people. Within the Afro-Asiatic language phylum, the Chadic branch is linguistically close to the East African Cushitic branch although they are separated by ~2,000 km of territory in which different Semitic and Nilo-Saharan peoples live today. We show that only northern Cushitic groups from Ethiopia and Somalia are genetically close to Chadic populations. Thus, the archaeologically
and linguistically supported route of proto-Chadic pastoralists via Wadi Howar to the Chad Basin may have genetic support. Moreover, our molecular genetic date for the Chadic-specific L3f3 clade is consistent with the suggested Holocene dispersal."
A similar conclusion is found via in the Europpean Journal of Human Genetics, which abstracts the idea as follows:
"European Journal of Human Genetics (6 January 2010) | doi:10.1038/ejhg.2009.231

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

by Fulvio Cruciani , Beniamino Trombetta , Daniele Sellitto , Andrea Massaia , Giovanni Destro-Bisol , Elizabeth Watson , Eliane Beraud Colomb , Jean-Michel Dugoujon , Pedro Moral & Rosaria Scozzari


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|[ast]| are found concentrated in the central-western part of the African continent, where they can be detected at frequencies as high as 95|[percnt]|. Phylogenetic evidence and coalescence time estimates suggest that R-P25|[ast]| 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|[ast]| 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|[ast]| and about half of the few European|[sol]|west Asian R-P25|[ast]| 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|[thinsp]|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.
European Journal of Human Genetics advance online publication, 6 January 2010; doi:10.1038/ejhg.2009.231."
The R1b haplogroup contradicts the above analysis, because the R1b haplogroup is otherwise strongest in Europe, and not in Africa.

Quite the contrary, the high presence of the R1b haplogroup in Chadic language speakers helps to draw attention to the megaliths of the Central African Republic and raises again the question of who put them there and when. We allege that these were European seafarers in ancient days. See Das Tanum System – ein alteuropäisch-afrikanisches Vermessungssystem? pp.34 et seq.

At the John Hawks Blog in the posting The worm in the fruit of the mitochondrial DNA tree
he writes:

"François Balloux (2009) has a polemic in the online access area of Heredity presenting references about mtDNA selection, and arguing that the use of this single genetic marker is no longer warranted without support from other loci.
Yay! I've been saying that both here, and in peer-reviewed articles, for several years. I think serious workers know that one gene is not enough; two genes (mtDNA and Y chromosome, for example) aren't enough -- we have to integrate information across every possible source, genetic, skeletal, and anthropological, to really test hypotheses about the past."
At Dieneke's Anthropology Blog, Aaron - in our view correctly - wrote in the comments:
"From what I remember the study found trace amounts of U5 and U6 in North Cameroon, and the rest the female lines were L1, L2..etc Linguistics is a whole other can of worms, but the data supports northern origins of this ethnic group."
Haplogroup U (mtDNA) is described as follows:
"U5 had a common ancestor with its sister group, U6. What's interesting is that U5 and U6 are "sister mtDNA groups" with a common ancestor in N. Africa. Each mtDNA group has a sister group. A large proportion of Canary Islander are U6. The medieval Guanches of the Canary Islands also had U6. There was a lot of interbreeding in paleolithic times between U5 and U6. The Berbers are high in U6 mtDNA today.

Haplogroup U6 is a group of people who descend from a woman in the Haplogroup R branch of the Genographic tree. It is common (around 10% of the people) [1] in North Africa and the Canary Islands. It is also found in the Iberian peninsula and British islands due to ancient gene flow from North Africa."

Thursday, February 4, 2010

The Peopling of the World via the Journey of Mankind : A Virtual Global Journey at the Bradshaw Foundation via an Animated Map

John Hawks Weblog has it right:
"It is really not worth looking at, but I couldn't stop laughing, so I have to point it out....

This is what we get when there is not enough critical science of human dispersals. We're not seeing history here, we're making it up."
Many conceivable maps of human migrations can be made based on the genetic and climatological evidence currently available. The map-animated virtual global journey at the Bradshaw Foundation Journey of Mankind : The Peopling of the World is one admirable attempt - at least from the graphics side - to provide such a map.

However, the graphics are where the fun ends - and the erroneous content begins, especially because of all the overstretched and unsupported climatological - and other - hypotheses....

Especially disturbing in terms of the available evidence is the idea that mankind first moved up the Nile Valley out of Africa - and then allegedly became extinct. A new subsequent group of humans - luckily kept in reserve in Africa in the interim - then allegedly reached Asia and Europe via the Arabian peninsula in a topographically navigational miracle and from there spread throughout the globe. A very unlikely scenario.

For a much more likely version of human migrations, see the National Geographic Genographic Project. And even there, great caution is advised. Too many details still need to be unraveled.

Y Chromosome Evolving Rapidly -- Gibbons 2010 (113): 3 -- ScienceNOW

Y Chromosome Evolving Rapidly -- Gibbons 2010 (113): 3 -- ScienceNOW:
by Ann Gibbons, ScienceNOW Daily News, 13 January 2010
"The Y chromosome has long been thought of as a stagnant part of the genome, where genes are slowly decaying in males of all species. But the first comprehensive comparison of the Y chromosome in two species--specifically, humans and chimpanzees--shows that in fact, it is a hot spot of evolution. 'It's really exciting; it's totally well-documented; it's really dramatic,' says population geneticist Andrew Clark of Cornell University.

As is well-known, humans and chimps share 98% of their DNA. But more than 30% of the DNA differs between chimps and humans in the region of the Y chromosome that determines sex. This suggests that the Y chromosome has undergone 'extraordinary' remodeling in both species in the 6 million years or so since they split from a common ancestor, says geneticist David Page, director of the Whitehead Institute of the Massachusetts Institute of Technology in Cambridge."
Read the rest of the article here.