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luis77
01-09-11, 20:57
Dienekes is posting some of the more interesting abstracts from the upcoming ICHG 61st annual meeting in Montreal, in October.

http://dienekes.blogspot.com/2011/08/ichg-2011-abstracts-are-onlineic.html

Here is one we are definitely looking forward to:

LD patterns in dense variation data reveal information about the history of human populations worldwide.

S. Myers et al.

Quote:
A detailed understanding of population structure in genetic data is vital in many applications, including population genetic analyses and disease gene mapping, and relates directly to human history. However, there are still few methods that directly utilize information contained in the haplotypic structure of modern dense, genome-wide variation datasets. We have developed a set of new approaches, founded on a model first introduced by Li and Stephens, which fully use this powerful information, and are able to identify the underlying structure in large datasets sampling 50 or more populations. Our methods utilize both Bayesian model-based clustering and principal component analyses, and by using LD information effectively, consistently outperform existing approaches in both simulated and real data. This allows us to infer ancestry with unprecedented geographical precision, in turn enabling us to characterize the populations involved in ancient admixture events and, critically, to precisely date such events. We applied our new techniques to combined data for 30 European populations sampled by us, or publicly available, and the worldwide HGDP data. We find almost all human populations have been influenced by mixture with other groups, with the Bantu expansion, the Mongol empire and the Arab slave trade leaving particularly widespread genetic signatures, and many more local events, for example North African (Moroccan) admixture into the Spanish that we date to 834-1394AD. Dates of admixture events between European groups and groups from North Africa and the Middle East, seen in multiple Mediterranean countries, vary between 800 and 1700 years ago, while Greece, Croatia and other Balkan states show signals of admixture consistent with Slavic migration from the north, which we date to 600-1000AD. At the finest scale, we are able to study admixture patterns in data gathered by a project (POBI) examining people within the British Isles. Our approaches reveal genetic differences between individuals from different UK counties, and show that the current UK genetic landscape was formed by a series of events in the millennium following the fall of the Roman Empire.

Comments from Dienekes "Existing methods for dating historical admixture events differ from each other by a factor of two, and they all assume a 2-population model. Hopefully the research described here will be an improvement..."

Knovas
01-09-11, 21:11
You are obsessed posting everything you see relating Spaniards and North Africans...what a sick agenda.

First of all, it is impossible to measure the age of the componenets in a population. However, the presence of North African admixture in places wich were never conquered by the Moors, suggest that the vast majority must be ancient. More or less is what the text is saying...a range between 800 and 1700 years it's not exact in any case. There are so many open possibilities, and in places never conquered the answer it's very easy to infer.

sparkey
02-09-11, 00:37
There's also a new abstract from Sir Walter Bodmer and the People of the British Isles for a presentation for it, see here (http://dna-forums.org/index.php?/blog/2/entry-176-people-of-the-british-isles-at-ashg/). Both Bodmer and Myers look like they'll be supporting a significant Anglo-Saxon influence on England (but probably not Cornwall or Wales):


Our approaches reveal genetic differences between individuals from different UK counties, and show that the current UK genetic landscape was formed by a series of events in the millennium following the fall of the Roman Empire.


When the appropriate geographical position of each individual within a cluster is plotted on a map of the UK, there is a striking association between clusters and geography, which reflects to a major extent the known history of the British peoples. Thus, for example, even individuals from Cornwall and Devon, the two adjacent counties in the southwestern tip of Britain, fall into different, but coherent clusters.

So I'm looking forward to these two especially.