Anyway, with the exception of my Portuguese great grandfather Harry Henriques, my ancestry is almost entirely Germanic and Celtic, and the hybrid Germanic/Celtic culture of the Anglo-Scottish borderlands which became an integral part of the American landscape is the entirety of my cultural and linguistic ancestry. (On my mother's side, I'm more typically Yankee by genetics, but it contributes surprisingly little to my personality and culture. In any case, the Yankees are also Germanic/Celtic hybrid anyway, as are the entirety of the British people and their diaspora descendants like the Americans, Canadians, New Zealanders, South Africans and Australians. Even the Scottish and Irish people had significant admixture from Anglo-Saxons, Vikings and Normans.)
So, while I talk a lot about Indo-European here, because it's a particular and keen interest of mine personally, I'm also keenly interested in the processes by which a subset of the Proto-Indo-Europan community became Celtic and Germanic. Sure, I think the Scythians are really interesting, and the Mycenean Greeks or Tocharians are fascinating, but my personal investment in their history is relatively lower, because they are not my actual ancestors, but the "cousins" of my ancestors. They're my people too, but much more distantly related, and not directly formative to me personally (odd theories of Sarmatians with the Romans in Britain and whatnot notwithstanding. Even if those speculative histories are true, they don't really matter too much as they contributed almost nothing genetically, culturally, or linguistically to the formation of the British people who later became the Americans.) There are three major inputs necessary to create Western Civilization as we know it (and depending on exactly who you talk to, the inputs are slightly different, but these are the three that I consider most crucial): 1) the cultural legacy of Classical Antiquity, i.e., the Greeks and Romans, 2) Christianity, and 3) the traditions and culture of the Germanic tribes that overthrew the political power of Ancient Rome and ruled both the Holy Roman Empire as well as numerous petty kingdoms and chiefdoms over areas of the former Empire. This includes the input of the Visigoths into Hispania, and much more thoroughly, the Franks in France, the Anglo-Saxons in England, the Lombards in Italy, and various Germanic tribes later consolidated by Frankish dynasties in what is now Germany and the Low Countries. The Scandinavian and northern Germanic people on the other hand, got their Greco-Roman and Christian history relatively late, and represent a higher admixture of cultural Germanic-ness than most; they didn't superimpose themselves over any lingering Celtic or Romanized culture.
These Germanic traditions which in the Middle Ages included and evolved into Salic law, assemblies of freemen (the Thing as it's sometimes called), feudalism and manorialism as an evolution of chieftain-king patronage, created Western Civilization as we know it. Lack any of those inputs, and you get similar yet also very notably different civilizations, like that of Eastern or southern Europe, as an example. I also prefer to see "real" Western civilization as requiring the outbreeding and manorialism which took place within the Hajnal Line, so I see peoples like the Spanish, Irish, southern Italians, etc. as "fringe" Western Civ at best, and just outside Western Civilization at worst, with their own civilization that parallels Western Civilization in many ways (because it had two of the three inputs the same) but not compatible in the same way as those within the Hajnal line. Some people take exception to this, and want to see southern Europe as equally Western Civilizational as Northwestern and north Central Europe, but I don't buy it. It's a different civilization with different values, different behaviors—and specifically, it lacks a very heavy dose of the input of number three in my list of three inputs necessary to create Western Civilization. UPDATE: As an aside; this coincides with Vox Day's third point, which is the European nations instead of the Germanic tribal traditions. If you read hbd chick's seminal work on the Hajnal Line and it's impact on the people who grew up in it, you'll find that the Third Point requires the European nations. The generations of behavior modification that manorialism and outbreeding created are what gives us the impact of the three pillars of Western Civilization; i.e., you can't adopt into Western Civilization (at least not in large numbers) because you will then cause it to drift from Western Civilization and only be some other civilization aping the superficial aspects of Western Civilization. To get Western Civilization out of theory and applied to reality, you need, of course, the European peoples who have gone through a thousand year (or more) crucible of Christianisation, Germanic traditions of independence and freedom, and Greco-Roman tradition,
How does Celtic fit into this? As a significant portion of my ancestry is Scottish, and even the British people are significantly Celtic, that's an interesting question, but curiously, it's not clear how much cultural debt we owe to the Celts, even if we do owe obvious mtDNA debt to them. The Celts obviously spread widely across Europe prior to the expansion of the Germanic and western Slavic peoples, but before that happened they were pretty solidly Romanized culturally, if not genetically. Only in the British Isles (and later places like Armorica/Brittany, which came from the British Isles) did they maintain their languages and some of their distinct culture well into historical times. I do think that it's fair to say that even the Scottish people, however, are pretty thoroughly Anglicized culturally. Whatever inputs the Celts had into the later specifically Germanic societies that dominate Western and Northern Europe (and the diaspora nations, like America), it's probably impossible to recover specifically what it is. But keep in mind that prior to the spread of Roman and Germanic culture to the areas that are today Western Civilization, they were Celtic, and especially in many of the core areas that were once the Hallstatt culture, Gaul, the British Isles, etc. the Celts never went away, they were merely absorbed culturally.
Anyway, after all that, here's some text from Eupedia on the formation of the Germanic people specifically. Keep in mind that while this speaks of the "Afro-Asiatic substrate" as if it's a given, it's actually completely speculative. Nobody knows what languages the EEF and WHG substrate population of Europe spoke before Indo-European languages replaced them, but given the very small number of data points that we do have; Etruscan, analysis (what we can) of Pelasgian, the Paleohispanic languages, Minoan, and the still extant Basque language suggests that it was not Afro-Asiatic at all. When it says below that it's "known" that Celtic borrowed grammar from Afro-Asiatic, that's not true at all either. We don't know that, it's one theory based on some similarities that may or may not be based on legitimate analysis. Frankly, I find it unlikely. There are loads and loads of theories and proposals linking Afro-Asiatic to everybody, and I think there is little reason to invoke them here. But I should note that loads of people, especially people who don't specialize in answering that question, or in pre-Indo-European Europe in general, do tend to assume that Afro-Asiatic was associated with the Neolithic Revolution and that the EEF population spoke Afro-Asiatic. Even David Anthony made a brief off-hand reference to the idea in The Horse, The Wheel and Language. Since there's no trace of Afro-Asiatic in Europe that didn't come with much more recent MENA or Jewish immigration to the continent, that's almost impossible to take seriously, though. Given that the EEF supposedly came from Anatolia, it's more likely that linguistically they were distant relatives of the Hattians or Kaskians than Afro-Asiatic anyway. The logic that calls EEF linguistic Afro-Asiatics is shockingly weak.
The first major expansion of R1a took place with the westward propagation of the Corded Ware (or Battle Axe) culture (2800-1800 BCE) from the northern forest-steppe in the Yamna homeland. This was the first wave of R1a into Europe, the one that brought the Z283 subclade to Germany and the Netherlands, and Z284 to Scandinavia. The Corded Ware R1a people would have mixed with the pre-Germanic I1 and I2 aborigines, which resulted in the first Indo-European culture in Germany and Scandinavia, although that culture could not be considered Proto-Germanic - it was simply Proto-Indo-European at that stage, or perhaps or Proto-Balto-Slavic. (editor: That Y-DNA Haplogroup I1 and I2 aboriginal population represents the Scandinavian Hunter Gatherers, or SHG, a population that isn't exactly a hybrid necessarily, but does represent a cline of being related to WHG and EHG both. This is represented by the Funnelbeaker and Globular Amphora cultures of pre-Indo-European Europe. Calling the Corded Ware Balto-Slavic is also nonsense; Balto-Slavic did indeed evolve out of a central Corded Ware horizon most likely, but at this stage, this is way before anything that can reasonably be called Balto-Slavic exists. Possibly we are talking about a very early semi-satemized version of Proto-Indo-European, however.)
Germanic languages probably did not appear before the Nordic Bronze Age (1800-500 BCE). Proto-Germanic language probably developed as a blend of two branches of Indo-European languages, namely the Proto-Balto-Slavic language of the Corded-Ware culture (R1a-Z283) and the later arrival of Proto-Italo-Celto-Germanic people from the Unetice culture (R1b-L11). This is supported by the fact that Germanic people are a R1a-R1b hybrid, that these two haplogroups came via separate routes at different times, and that Proto-Germanic language is closest to Proto-Italo-Celtic, but also shares similarities with Proto-Slavic.
The R1b branch of the Indo-Europeans is thought to have originated in the southern Yamna culture (northern shores of the Black Sea). It was the first one to migrate from the steppes to the west, invading the Danube delta around 4200 BCE, then making its way around the Balkans and the Hungarian plain in the 4th millennium BCE. It is likely that a minority of R1a people accompanied this migration of R1b tribes. Those R1a men would have belonged to the L664 subclade, the first to split from the Yamna core. These early steppe invaders were not a homogeneous group, but a cluster of tribes. It is possible that the R1a-L664 people were one or several separate tribes of their own, or that they mixed with some R1b tribes, notably R1b-U106, which would become the main Germanic lineage many centuries later. The R1b-R1a contingent moved up the Danube to the Panonian plain around 2800 BCE, brought to an end the local Bell Beaker culture (circa 2200 BCE) and Corded Ware culture (c. 2400 BCE) in Central Europe, and set up the Unetice culture (2300-1600 BCE) around Bohemia and eastern Germany. Unetice can be seen as the source of future Germanic, Celtic and Italic cultures, and is associated mainly with the L11 subclade of R1b.
The late Unetice culture expanded to Scandinavia, founding the Nordic Bronze Age. R1a-L664 and R1b (L11 and U106) presumably reached Scandinavia at this time. The people of the Nordic Bronze Age probably spoke a Proto-Germanic language. For over a thousand years while this culture existed, the Proto-Germanic R1b et R1a-L664 tribes would have acquired vocabulary from the pre-existing Corded Ware population that they assimilated, which was itself a blend of Proto-Balto-Slavic languages (linked to haplogroup R1a-Z284) and languages of non-Indo-European origin (linked to haplogroups G2a, I1 and I2). The Nordic Bronze Age was a melting pot of these three populations, which intermingled both genetically and linguistically, little by little creating a new ethnicity and culture as time went by.
The first genuinely Germanic language has been estimated by linguists to have come into existence around (or after) 500 BCE, just as the Nordic Bronze Age came to an end, giving way to the Pre-Roman Iron Age. The uniqueness of some of the Germanic vocabulary compared to other Indo-European languages suggests that borrowings from indigenous pre-Indo-European languages took place (Germanic substrate theory). The Celtic language itself is known to have borrowed words from Afro-Asiatic languages spoken by the descendants of Near-Eastern farmers who had settled in Central Europe. The fact that present-day Scandinavia is composed of roughly 40% of I1, 20% of R1a and 40% of R1b reinforces the idea that the Germanic ethnicity and language had acquired a tri-hybrid character by the Iron Age.Of course, that definition is somewhat arbitrary. Proto-Germanic is generally defined as the language that had undergone the Grimm's Law sound shift. That isn't to suggest that prior to that sound shift the early Germanic wasn't already on its way towards becoming proto-Germanic and was already separated from every other Indo-European language, merely that it hadn't yet undergone a somewhat arbitrary degree of divergence from late Proto-Indo-European division. The stage of the language after the split from Proto-Indo-European but prior to Grimm's Law and the stage called proto-Germanic is sometimes called the Germanic Parent Language. Other workers divide the whole shebang into three stages; pre-Proto-Germanic, Early Proto-Germanic and Late Proto-Germanic. Either way, this is the language of the Nordic Bronze Age, strictly defined proto-Germanic is the language of the pre-Roman Iron Age, and the break-up of Common Germanic into the various branches that later emerged as Norse, Gothic, English, Dutch, etc. is somewhat well documented in the historiography of the Romans and corresponds to the Migration Period.
And here's some really interesting commentary on the Bell Beaker phenomena which preceded the Unetice and overlayed the Corded Ware to some degree. Guys like Carlos Quiles say that the Beaker was associated with R1b and the Corded Ware with R1a, which has led him down the rabbit hole that Corded Ware can't be Indo-European because the Bell Beaker has to be the spread of the Indo-European languages, but this makes no archaeological sense. (Although to be fair to him, he seems to realize that "Eastern" and "Western" Bell Beaker culture is not the same thing ethnically.) The Bell Beaker started on the Atlantic Coast and the British Isles long before the arrival and population replacement of genetic lineages that we do actually see, which are associated with Indo-European colonization. Anyway, although I'm quoting this, it was a sloppily written forum post, so I've edited it somewhat for grammatical correctness.
I have noticed that Jean Manco mentioned in her new book Ancestral Journeys that the Bell Beaker culture represents the arrival of R1b people into Western Europe. I have explained before why it is extremely unlikely that R1b spread from southwest Iberia towards Central Europe. I would like to stress now that the Bell Beaker phenomenon was not an ethnic culture like most other cultures of the period, but rather represents a huge multicultural trade network inside which a variety of new artifacts, customs and ideas were exchanged and diffused.
In my eyes, the Bell Beaker phenomenon was indeed caused by the contact between the Megalithic people of Western Europe (who were an ethnic fusion of Mesolithic inhabitants (WHG) and Neolithic immigrants from the Near East(EEF)) and the Indo-European cultures of Central Europe. What is striking about the Bell Beaker period is that it does not replace any anterior culture, but simply juxtaposes itself on top of pre-existing cultures and new cultures alike. The Bell Beaker phenomenon last from 2800 to 1800 BC and was contemporaneous with the following cultures:
A) The Megalithic culture which emerged in Western Europe (incl. Sardinia) as soon as the Neolithic reached the region, starting from c. 5500 BC and only came to an end with the arrival of Bronze Age cultures from Central Europe, starting c. 2200 BC in Britain and lasting as late as 1200 BC in isolated parts of Iberia.
B) The Corded Ware culture which existed from 2900 to 2350 BC in Germany, Central Europe and the Baltic. It is associated with the partial replacement of Neolithic LBK- and TRB-related male lineages by R1a lineages.
C) The Unetice culture, which replaced the Corded Ware culture in Germany, Bohemia and western Poland from 2300 BC and lasted until 1800 BC. It marks the fusion of R1b lineages with Corded Ware lineages, although some R1b tribes were already present around Hungary at least since 3000 BC, and arrived in Germany during the Corded Ware period.
What is interesting is that we see the progressive disappearance of the Megalithic culture in the British Isles, Belgium, France and northern Italy between 2300 and 1800 BC, right in the middle of the Bell Beaker period. The Beaker phenomenon was present in these regions several centuries before the arrival of Bronze Age cultures, but survived for a while, unlike Megalithic cultures. In and around Germany, the Corded Ware culture (R1a Bronze Age) was replaced by another Indo-European Unetice culture (R1b Bronze Age) that was the result of the migration of different people (R1b) from the Danube region. And yet the Beaker phenomenon survived, because it was not directly associated with a particular ethnic group, but was an international trade network.
Another evidence of the pluriculturality of the Bell Beaker phenomenon is that there were very distinct types of Beaker pottery in Indo-European Central Europe (the cord-impressed types, such as the "All Over Corded") and the Megalithic Western Europe (the "Maritime" type, decorated with bands filled with impressions made with a comb or cord).
It is not a coincidence that the Beaker phenomenon has been divided by archaeologists into several groups. People who made Maritime beakers were simply not the same ethnic group as those who made or used beakers in Central Europe. This is obvious from mtDNA samples we have from this period.
In German sites containing beakers we see clearly Indo-European lineages like H4a1, I1a1, T1a, U2e, U4c1 and W5a, mixed with earlier Neolithic of Mesolithic lineages (H1, H3, T2e, U5).
But in Spain, all the mtDNA lineages are in clear continuity with earlier Neolithic samples. Iberian beakers samples tested to date include H1, H3, H14, H20 (or L3), J, K, L1b, L2, L3a, T2, U, V and X.
The beaker trade network obviously involved some minor population movements across Western an Central Europe. I have no idea if the trade was dominated by people from one specific region, but I doubt it. Some R1a and R1b lineages from Central Europe might have ended up in Western Europe following trade routes during the early Beaker period. It is however unlikely that any large-scale migration or invasion of R1b people occurred before we see the archaeological replacement of Stone or Copper Age cultures using common Megalithic burial (e.g. passage graves) by Bronze Age cultures using single graves. This would have happened in the late Beaker period, hence the common, but mistaken assumption that the Beaker phenomenon itself represented the invasion of Western Europe by R1b people. Forget the bell beakers as an ethnic culture. It was more like a Silk Road than a culture of its own.