Ancestry by Y chromosome

I have recently become more interested in my family's heritage. On my mothers side, we've traced an ancestor to the Mayflower, Isaac Allerton, one of the signers of the Mayflower Compact. On my father's side, all we really know is that my grandfather was Czech (hence Fiala b a Czech name) and my grandmother was Polish. We don't even know if their home villages still exist.

But, thanks to the Genographic Project at National Geographic, I now know the path of my great, great, ... , great grandfather, part of the M172 line of human migration, who lived on the Mediterranian 10,000 years ago:


For context, here's a map of a larger set of migrators:


What's interesting is that the incidence of the M172 line is in fact very rare in Eastern Europe. Here's a density map for the line:


I have put my Genographic results up on my website here. There's a lot of resources out there for M172, including a Wikipedia entry, a blog dedicated to the line, a compilation of resources at another blog, and a website that looks at some of the finer movements in the line.

To put the test in perspective though, a friend recently explained its limits:

This doesn't mean that "You" or "Your family heritage" are Southern European. Suppose you consider all of your relatives 1000 years ago, assume 25 year generations, that is 40 generations, giving you 2^40 great etc grandparents then (assuming no interbreeding) (I think my math is right, but anyway, it is a lot). Your Y DNA is from one of them, and gives no information about all the others. So even if all the others were from eastern europe, one marauding phoenecian could ruin the whole thing.

These designations are only accurate to about 10000 years ago in terms of mutation differentiation. so your Y cromosome could have been in eastern europe for the last 9000 years, and really like vodka, borscht, and bohemian beers.

The Genographic Project will "test either your mitochondrial DNA, which is passed down each generation from mother to child and reveals your direct maternal ancestry; or your Y chromosome (males only), which is passed down from father to son and reveals your direct paternal ancestry." These results are only for the paternal ancestry. The next steps include getting my mother's brother to do the test for our great grandfather on that side, and then doing the maternal ancestry for myself and my father.