Who is a Celt?

[Diabolical Materialism]

I've been doing a reading about pre-Roman Gaul and I came across a controversy I didn't know existed. The actual definition of Celt seems to be pretty fluid among historians, and there isn't a single standard that is accepted by even a majority of those studying the Celtic people. So I thought I'd bring the question to y'all. Who is a Celt? Were the Gauls Celts? The Galatians? The Britons?

[Diabolical Materialism]

@ 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?

Yes, in the last few centuries BC the Alps were inhabited by various Celtic peoples. Illyria (what is now Croatia, Bosnia and bits of Serbia) was inhabited by various Celtic groups like the Boii and Volcae at least into the third century BC.

The Galatians and the Serdi went even farther east, settling in Anatolia and Thrace respectively. But the extent to which the Serdi, Boii, and Volcae can be considered "Celtic" is up to debate. The literate peoples they encountered seemed to imply that they were at the least.

[Diabolical Materialism]

^ 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.

Yeah applying haplogroups to historical cultural groups can get hairy. Still fascinating stuff.