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alan
01-26-2014, 11:31 AM
I am interested to understand how long is the R1* period may have been. Can a period be estimated for when R1 diverged from other R but had not yet divided into lines leading to R1a and b? In SNP terms if there an identifiable period when there is a shared ancestry for future R1a and b that is not shared by any other R. I am basically wondering how long the period was where there was an R1 line with no divergence into further lines? Is that somehow estimable using SNPs STR variance or a combination of both. Help for this mathematically challenged person is much appreciated in advance.

Heber
01-26-2014, 03:53 PM
I am interested to understand how long is the R1* period may have been. Can a period be estimated for when R1 diverged from other R but had not yet divided into lines leading to R1a and b? In SNP terms if there an identifiable period when there is a shared ancestry for future R1a and b that is not shared by any other R. I am basically wondering how long the period was where there was an R1 line with no divergence into further lines? Is that somehow estimable using SNPs STR variance or a combination of both. Help for this mathematically challenged person is much appreciated in advance.


Alan,

Here is a very interesting interview with Chris Tyler Smith.
I met him at the DNA in Forensics Conference in Innsbruck in 2012.
He had just presented the CTS, Zhu and Wei initial results.
Three expansions in China, Africa, Europe with the most extreme being the R1b in Europe.
All three were due to the Neolithic in three continents.
He mentioned the tenfold expansion of the Phylogenetic Tree and the new found ability to count SNP to extimate the age of branches.
Two years on we are still waiting for the new Tree.


"Your study found that the European population lineage descended from as little as one to three men, in stark contrast to the African population that descended from about 40 men. Were you expecting to find such a difference? Do you have any thoughts on why this is?

Yes and no. The star-like expansion of R1b, with all the sub-lineages branching off the same central point, told us from just a glance at the tree that the expansion had to be so rapid that there had not been time for mutations to occur during the period of expansion. The more regular tree-like structure of E1b1a similarly told us that the expansion had been more gradual. So we were expecting to see a difference. But we needed to do the simulations to get the numbers. Why are they so different? We can only speculate about this, but two factors may have been important. In Europe, the starting number of farmers may have been smaller, so there were fewer Y lineages. And the farming package, perhaps including several different crops and domesticated animals, may have been well-suited to the environment, so the farmers could increase rapidly in number."

"What’s next for your research?

In this area, I’m keeping a close eye on ancient DNA (aDNA) results. The same advances in sequencing technology that benefited our work are now transforming the aDNA field. Soon, we won’t have to depend on modern DNA and modelling to understand the past: we will be able to see more directly from the sequences of ancient samples. There are not many ancient Y sequences yet, but I’m sure they will be available soon. aDNA results from other parts of the genome are already supporting the idea of large-scale movement of farmers. I would also particularly like to see a better calibration of the Y tree, coming from measurements of mutation rates in modern families, or from aDNA, or preferably both. The next years of Y-chromosome research are going to be exciting."

http://www.biomedcentral.com/biome/a-tale-of-two-continents-chris-tyler-smith-on-modeling-male-lineage-expansions-from-africa-and-europe/

http://www.investigativegenetics.com/content/4/1/25

alan
01-26-2014, 09:33 PM
What I am primarily interested in this thread is the duration of the period between R* and R1* and the duration of the period between R1* and R1a and b. Can it be calculated?

Tomasso29
01-27-2014, 12:40 AM
What I am primarily interested in this thread is the duration of the period between R* and R1* and the duration of the period between R1* and R1a and b. Can it be calculated?

I highly doubt such numbers can be calculated.