First there was the tension between Germany and Greece over debt, and now there is the conflict over who is going to take in how many Syrian Muslim immigrants. The European Union is obviously a dead man walking, so why wait to take a postmortem look into why the bulk of Europe could never have held together. There is simply too wide of a chasm between two different groups of people.
A highly popular article in the New York Times took these groups to lie on either side of recent political and economic institutions – the former Communists in the Center and East of Europe, and the capitalists in the West. This misses the former countries of Yugoslavia, who are just as protective of their regional cultures as the Poles and Lithuanians, yet who were not Communist but market socialist, and who were led by Tito rather than Stalin.
So why not just modify it to capitalist West vs. non-capitalist East? That would still leave out a major player – Greece. The Communists lost the Civil War in Greece after WWII, and they joined NATO rather than the Warsaw Pact or the soft-socialist "third way" championed by Tito.
Clearly there's something deeper than just the political-economic differences of the past 100 years.
Peter Turchin took a longer-term look into the roots of the EU crisis, focusing on the debt crisis (that post was written two months before the current Syrian immigrant crisis). He points to the divide between the former core of Latin Christendom as led by Charlemagne, and the more Orthodox East.
As with the political-economic view, this view gets a good amount of the split, but misses key players. Poland has always been on the Catholic side, notwithstanding some support for Protestantism in the early stages of the Reformation. Ditto for Hungary, the Czech Republic (now mostly atheist), Slovakia, Lithuania, Croatia, and Slovenia. Granted, they were Christianized much later than the West, but it was always within the Latin rather than Byzantine tradition, and when they flirted with breaking from the Roman Church, it was toward one strain or another of Protestantism rather than Eastern Orthodoxy.
In the comments to that post, the pre-Roman Celts came up as an even older example of the European core in the lands later ruled by Charlemagne. That gets much closer to the true divide in Europe, which is racial and ethnic – between Celto-Germanic people in the West and Balto-Slavic people in the East.
The genetic anthropologist Dienekes Pontikos took a look into how various European individuals clustered genetically. It turned out that the Balts and Slavs formed a cluster, while the Celts and Germanics formed another, and that these were distinct clusters that hardly overlapped.
Matching that genetic separation, historical linguists are happy to lump Baltic and Slavic languages into a single Balto-Slavic group within the Indo-European family. They are willing to lump Celtic and Germanic languages into their own group as well, with the understanding that it is much older, has had far more time for its members to differentiate themselves, and therefore shows much less mutual intelligibility among its members than is found among Balto-Slavic languages.
Demographically, the split reflects the history of large-scale migrations, namely the Germanic migrations that intermixed them with Celtic and Italic peoples during the middle of the 1st millennium, and the later (Balto-)Slavic migrations of the second half of the 1st millennium. The Slavs began around what is now Ukraine, moved north into what is now Russia, then west into what is now Poland. Why didn't they continue westward? Because the Germanic peoples had already firmly settled into what is now northern Germany and the Low Countries.
This tug-of-war along the center of Europe between Germanic and Slavic populations has never gone away. We don't have to look back very far before the current EU crisis to find its most recent explosive form – the Nazi push to grab Slavic lands for Germanic lebensraum, and the Soviet capture of eastern Germany for Slavic control.
Taking a racial / genetic perspective also allows us to make sense of the greater rebellion against Muslim immigrants in eastern Germany today. In an earlier post, I reviewed evidence that eastern Germany used to be Slavic, although I assumed too much in describing the Germanic replacement as genetic. It could have been that a Slavic people adopted Germanic culture (language, religion, etc.), aside from interbreeding with them.
A later post looked at how genetically similar the Slavs are today, compared to the greater genetic diversity found among Germanic, Celtic, and Italic people. (That reflects the fact that the Slavs were the last major group to break off and settle down on their own.) But the study under discussion also shows that Germans have a non-trivial genetic kinship with Poles, Hungarians, and Czechs, i.e. with the Slavs nearest to them.
Still, their plot of who clusters with who puts the bulk of Germans with the Swiss, Dutch, and other Germanic groups, with a fringe group of Germans next to the separate Slavic cluster. I interpret that to reflect Germans in the sample coming from different parts of Germany, and that eastern Germans are substantially Slavic. Those PEGIDA protesters who are trying to run the Muslim immigrants out of town, are likely German-speaking crypto-Slavs. "Germanicized Slavs" doesn't sound quite right, since they evidently haven't adopted the full suite of Germanic customs, including the welcoming of invading foreign races.
Interestingly, in that study the Austrians cluster with the Eastern group (Slavs). If their Austrian sample reflects population density, they likely hail from Vienna, which sits in the far eastern part of the country, surrounded by Slavdom. Vienna lies closer to Bratislava, Budapest, Prague, and Ljubljana than it does to Munich. And of course it shared capital status with Budapest during the Austro-Hungarian Empire. In the current immigrant crisis, they seem to be as wary as the Hungarians about having a bunch of foreigners settle their country, and want them to either not enter in the first place or to hurry on to Germany, France, Sweden, etc., where they'll receive a warm welcome.
More surprisingly, in the genetic study the Greeks, too, clustered with the Slavs rather than with the Italic / Mediterranean group. Maybe not so surprising, considering that the Slavs settled so much of the rest of the Balkans during Medieval times. The Greeks weren't as closely related to any Slavic group as any Slavic group was to another, but they do show a substantial Slavic imprint. (You'd be surprised how many modern Greeks are blond-haired, blue-eyed folks-who-never-smile.)
That may be more than you ever wanted to know about the genetic roots of Eastern and Central Europeans, but it's worth wrapping your mind around in order to understand what goes on in that part of the world. The best way to describe the divide in the break-down of the EU is not economic or religious but genetic, between Celto-Germanic and Balto-Slavic peoples.
To appreciate why it's the Balto-Slavic side that is the more nationalistic side, read that post of mine about why there's so little separatism in Eastern Europe, and why Pan-Slavism nearly happened. Slavic individuals are much more genetically similar to one another than people of other European groups are to members of their own group. They are therefore more likely to band together in nationalistic ways.
So, it's not just a story about Eastern Europeans being more "homogeneous," i.e. more white, than countries with large immigrant populations. Even if you removed the non-European elements from Western nations like England, France, and Germany, the English, French, and Germans are still more genetically diverse amongst their countrymen than are the Poles, Lithuanians, or Serbians. Slavic populations are much younger and have not had as much time to diverge and differentiate.
Greater genetic similarity means greater ability to organize collectively for group protection. The jump from "the clan" to "the nation" is not such a quantum leap among Slavs as it is among Germans.