Who is a Celt?

[RINO Tom]

While it could be broadly or narrowly interpreted, Celts are pretty clearly the descendants of speakers of the proto-Celtic languages, who were themselves descended from proto-Indo Europeans (and possibly proto-Italo-Celtic people in between).  If we are talking about genetics/admixture/whatever, there were obviously certain areas where Celts displaced the original Neolithic populations a lot more (e.g., places with high frequencies of R1b-L21), and places where a smaller group of Celts imposed their language on the existing Neolithic population and sort of "Celticized" people who weren't previously culturally Celtic (e.g., areas like Galatia, where haplogroups from previous populations remained in the majority).  Usually, historians simply consider a people who speak a certain language to be of that cultural group, not caring much about admixture.  If we get too caught up in the latter, we wind up distinguishing between "Greeks" and "Pelasgians," which just gets too messy.

No historian worth his or her salt would say the Gauls weren't clearly Celts.  I have seen maps where "Gauls" is labeled over modern-day France and "Britons" is over the British Isles, while simply "Celts" is over areas of Central Europe.  I think this is simply due to the notoriety and historical relevance of the previous two Celtic peoples.  It would be like labeling "Germanic Peoples" over Germany in a map of Fourth Century Europe, while labeling "Norse" over Scandinavia.  Both are Germanic peoples, but the "Norse" had separated themselves somewhat culturally by that time, and the name "Norse" became quite relevant during the Viking Age and rings a lot of bells with modern people.  More or less, the Gauls were famous enough for their wars against Rome that they got their own label ... but "Gauls" are definitely "Celts," as are "Britons."

When it comes to modern peoples, one has to rely almost exclusively on language or at least cultural traditions.  For example, many Frenchmen would carry DNA disproportionately more similar to the Ancient Gauls than the Ancient Romans, but the French are still considered a Romance (Latin/Italic) people due to their language and their culture, with only Brittany retaining a true Celtic heritage.  Additionally, while actual Celtic languages are in the minority in much of Ireland, Wales and Scotland, those countries are still largely considered "Celtic" due to a combination of self-identification and cultural affinity for Celtic traditions.

[RINO Tom]

@ The above: haven't parts of modern-day Austria and even the Balkand been identified as having been Celtic at some point? And if so, is that the result of a nebulous definition, of migration over time?

I believe most experts think the Proto-Celts broke away into their own separate group (possibly/probably a split with the Italics who went south) in an area around modern day Austria, making that a sort of “Celtic homeland.”  I believe there has been a sort of “Celtic revival” in Austria in modern times that looks to celebrate this, being born in the decades after World War II as fewer and fewer Austrians identify as ethically German, and therefore Germanic.  I think I saw on Wikipedia once that around 80% of Austrians simply identified as “Germans” before WWII, while around 7% or something do today.  Obviously, the nation of Austria would trace its roots, for all intents and purposes, to Germanic founders and Germanic culture, though I think some Austrian (and Bavarian) traditions have always had a Celtic influence in some places?  Not sure.

I’m not an expert on this, either, but I think it’s harder to look for “Celtic DNA” (to the extent such a thing exists) in that region because it was much easier to identify other haplogroups (like R1b-L21) specifically with the movement of Celtic populations, explaining why it’s concentrated in Ireland, Britain and Northwest France, but it’s a lot harder to distinguish the makeup of Austria and determine how many of the original Celtic inhabitants were displaced/mixed with Germanic migrants.  Then, of course, there are large chunks of Europe who aren’t mainly descended from ANY Indo European groups, having a lot more admixture from Neolithic Farmers, and Austria is significantly closer to where that gets to be more of the case than even Central Germany.  Lot of Slavic admixture, too.

[RINO Tom]

^ Obviously, we need to be careful to not oversimplify or anything, and there are exceptions and stuff.  There was indeed R1b in Europe before Indo European invasions/migrations, and it is my understanding that we can really only identify certain haplogroups somewhat confidently with specific cultures if it is a certain subclade.  For example, I already mentioned R1b-L21 for Celtic peoples migrating to the British Isles and Ireland, and I believe we can also be very confident that R1b-U106 is a clear marker of Western Germanic tribes.

Another thing is that haplogroups only trace an original male ancestor.  A plurality of Finnish men still carry haplogroups generally associated with Proto-Uralic peoples, but autosomal studies show that Finns, on average, have very high levels of Indo European admixture.  After all, if Uralic Bob marries a Germanic woman thousands of years ago in Finland, and their son marries a Germanic woman and this process continues for ten generations, Bob's contribution to his male ancestor will be less than 1%.

However, it is also my understanding that we can really only classify "admixture" confidently into broader categories, colloquially...

- Hunter Gatherers who were in Europe for over 8,000 years
- Neolithic Farmers who came to Europe from Anatolia shortly after
- "Indo Europeans" who invaded Europe and spread their languages, eventually involving to the majority of cultures in Europe today (with exceptions like Basque or Uralic peoples)

I remember seeing one time that the largest admixture for the first category is around the Baltics and Finland, the second is highest in Sardinia and Basque Country and the third is generally higher in Northern Europe.  As you mentioned, it gets complicated because Basque Peoples pretty clearly have some of the highest levels of Neolithic Farmer DNA, but they also have some of the highest rates of R1b.  I think experts are still learning.

I love this stuff, though, haha.