Media Starts to Gets Home DNA Testing for Ancestry Right -- Thank God!

Kristen V. Brown is back with an excellent piece for Bloomberg, on home DNA testing, that is remarkably astute for a piece in the popular media.  

It confirms much of what readers of this blog have seen posted here repeatedly.  It's so good, it's worth quoting at length:

DNA is great at identifying familial relationships like parents, grandparents, aunts, uncles and even second and third cousins. Beyond that, it gets fuzzy.

The genes that make you a superfast runner or that identify you as Irish are less well-studied. The accuracy of any one test depends on the data your DNA is being compared to. One 2009 journal article said consumer DNA tests were akin to horoscopes exploiting the human tendency to hunt for patterns in meaningless data.

So what does it mean when a test says I’m 25 percent Irish?

It’s a misconception that these tests can tell you where your DNA was in the past. 

If a test tells you that you’re 25 percent Irish, what it actually means is that you are genetically similar to other people who are a part of the reference data set of Irish DNA that the company has collected. 

Because each company uses a different algorithm and data set, your results may vary based on which company you use. 

In other words: Take all this with one very large pinch of salt!

Meanwhile, in Slate, appeared another excellent piece by John Edward Terrell.  Here's the quote for you to read for yourself:

Whatever the motivations, the current popularity of commercial genetic profiling worries me for two reasons. One is that these companies may be promising results they can’t actually deliver. 

The notion, for example, that our genes can be used to trace our personal ancestry far back into the past—say, to Genghis Khan, the Emperor Charlemagne, or one of the pharaohs of ancient Egypt—makes little statistical sense. You may disagree, but to me this comes across as selling something more akin to snake oil than science.

What worries me most, however, is that companies offering personal genetic testing customarily seem to report back to those sending along a sample of their spit that they are a mix of different “ethnicities.” This is more than simply statistical nonsense.

We are happy that the mainstream media is finally getting it right, instead of publishing starry eyed pop-sci nonsense about DNA tests.

Don't ever forget: if you come from Central Europe (France, Germany, Italy, or nearby countries), or if you come from a country where there are simply insufficient samples (much of the rest of the world), these DNA tests will wipe your heritage off the map, by telling you that you are something else.  Basically, they're most accurate at the Continental level, unless you happen to come from an island in Europe with massive amounts of people getting tested, i.e., the U.K.

Italy in Roman Times - The Genetics of the Ancient Romans, Part II

Here's a great graphic that I was made aware of.  It shows Italy's ancient borders, during the Classical Era, basically the dawn of recorded history through Greco-Roman times.

Sure, the ancient borders have been shaded within modern Italian provincial borders, and thus are rough or "rounded to the nearest modern border."  But I've checked this with other maps, and found that it quite accurately depicts Italian borders on the dates it covers.

There are two takeaways, one which is directly related to genetics:

1.  Metternich's oft-repeated slur that Italy is just a geographic expression is nonsense.  There is a 2000+ year history of the peninsula being unified, and 1800 years of Italy even including the islands, like Sicily.

2.  So who then has a claim on being more Italian?  You often hear Northern Italians say they do.  

Well, surely it is the provinces that have been known as Italy the longest, those which were romanized first.  And those are, in order, the ones in teal, green, and magenta on the map.  

(As the map notes but doesn't make clear: Caesar crossing the Rubicon was so significant because that was the border of Italy!)

If one mentally superimposes on this geopolitical map an actual demographic map showing Roman colonies...

...one can rather easily see that the current genetic clines of Italy are at least partly explained by which regions were first unified as Italian / Roman.  

This brings me to what any college-level history student can tell you: for hundreds of years, Rome was an exporter of humans.  Romans and Latins were wealthy compared to others in the world, and had lots of children, and their dominant political situation meant they could settle colonies at will.  

It's time to consider that the genetic "southernness" of certain parts of Italy and the Mediterranean could easily be due to Roman colonies causing people there to resemble south-central Italians -- as opposed to the common yet misguided theory that more recent "invasions" to isolated Italian mountain towns by Saracens caused the people there to genetically resemble the latter.