taf wrote 31/05/2016 21:18 >>On Tuesday, May 31, 2016 at 9:53:17 AM UTC-7, joe...@gmail.com wrote: >>Y-DNA has a lot more depth on the chart, but autosomal has much more bredth in lieu of depth. Both useful, but in different ways. >I think Andrew was talking about a different type of autosomal analysis than you are. He was talking about SNP analysis used to determine ethnic proportions - basically useless for genealogy unless you don't know if your grandfather was a Finn or an Italian and you know everyone else is neither. What is more useful is the autosomal SNP clustering analysis that looks at conserved islands of contiguous DNA and can tell you someone is related to you within about a half-dozen generations. While it has limits, that can be useful data, though it proves no specific connection. Well I agree with both of you in a way. Autosomal testing can indeed be useful in genealogy. But in reality the autosomal testing is the same for both the ethnic studies and the genealogical ones you mention. What differs is the technical analysis then done with the masses of raw data that result. For genealogy both the older and newer technologies are limited in practice for now concerning their ability to name exact relationships within a tree. Both require triangulations that compare multiple people at the same time, and these are difficult to do without a single database being held by a central authority, such as a testing company or something like gedmatch. Such triangulation is specifically difficult in the traditional Y DNA STR testing because to draw a (male line) tree using those tests you need representatives of many branches of a line to test a very large number of markers, and neither the testing companies nor the professional and amateur genealogical community is investing in this direction. There seem to be decreasing returns to scale, and as taf says the likely future is that SNP testing (effectively the same test as the autosomal) can eventually replace this (and even give STR results at the same time). Basically, with SNP Y DNA testing a family tree of all tested male lines is being built and will eventually be able to be drawn down to a very recent level. But the triangulation using autosomal DNA is more complicated for another reason, which is that it deals with a mass of mixed DNA. Complex techniques need to compare people to determine which large blocks came from which recent ancestors. Though difficult, this is definitely now happening and giving real results for genealogy. To have success, you need however to hope that relatives have been tested. I have found matches which could then be confirmed by paper trail which went back as far as 1800 or so. The ethnic studies effectively look at the same types of blocks in autosomal DNA, but going down to much smaller blocks, shared by larger numbers of people, and going back to much more ancient ancestors. To do this, many small blocks must be considered at once, statistically, to see whether they are correlated, i.e. typically found in the same populations and sub-populations. When large numbers of small blocks of a similar size and age are strongly associated, this is assumed to define an "ancestral population" such as the "steppe component" taf mentioned. Because these can be assigned relative ages, population histories can be inferred, such as mixing of populations, or the splitting of populations, in a certain sequence. These ancestral components are often given names (such as "steppe") which are effectively guesses about who those ancestor groups were, but as new data has arrived, it has been very interesting how many simple ideas about human history have had to get more complicated and how the scientists involved have had to get more careful in their terminology and speculation. For all kinds of population history studies, Y DNA and autosomal, one quite simple problem is that just because a genetic marker is mainly found in one region today, this might not always have been the case. (In fact it seems such markers often move in waves, and are often most common at the edges of an expansion, not the original starting point.) Even the small amounts of ancient DNA so far tested have helped show this and shown many of the ideas that were spread around in the first years of such studies (many of which are still commonly held by the public) to be wrong. Best Regards Andrew