Well before the cis-/trans/assigned at birth issues became culturally central, personal identification by “national” origin/affiliation was an essential part of the modern global culture that arose across the 19/20C. While this frame of reference was often originally cast in terms of “race,” the meaning of that word has changed over time (we no longer talk about the Scottish “race” for example). That etymological shift was part of the nominal ‘scientification’ of race in the late 19C in which “Caucasian,” “Negro,” and “Asiatic” groups were assigned immutable characteristics and thus, the enabled the rationales for all manner of discriminatory/oppressive behavior, both across empires and within countries. Emerging sociological analyses talked about “national character” which was partially a continuation of the “race” discourse and partially a way to put a scientific gloss on discriminatory treatment.
In parallel, the concept of the “nation” as an ethno-linguistic grouping emerged and became the touchstone for ideas of political organization; initially across Europe, then globally. While this undoubtedly provided a “waystation” for highly localized cultures to deal with the globalizing world, the freezing of identity at the national level eventually led to any number of horrible developments across the 20C and has continued to animate politics in the 21C, with prospects paralleling those of the 20th. Internationalism and its sibling cosmopolitanism were earnest efforts, but almost always secondary to nationalism, even among the elites. For most folks, a national perspective was about as far as they could comprehend.
Despite the proclamations by politicians and group leaders in almost every country in the world, (thundering on about “blood-ties” or “[fill-in-the-blank] – ness)” the key point about national identity is that it is—in almost all cases—a construct of human culture. Just as evolutionary science has undermined the notions of separate black/white/yellow/red/brown “races,” so to do we have to recognize that—biologically—there are no “Irish,” “Arabs,” “Germans,” etc. (much less national identities in Africa and much of Asia (where chiefdoms and other local groups were either split or mashed together by European imperial line-drawing), South America (where chiefdoms and other local groups were overrun by Iberian invaders and interbred with them and imported African slaves).
Americans are, of course, mongrels. As are the Brits (German, French, Norse, Celts, later joined by a variety of imperial imports) and, in fact, almost everyone else. We have known this at an anecdotal level for some time, but now we are on the cusp of leveraging evolutionary genetics to make this clear at a scientific level. Specifically, the emerging specialty of paleogenomics studies the DNA of anthropologically-discovered ancient humans and creates lines of descent between extinct and modern populations. So far, it has undermined the bright line we all learned in school as between Neanderthals and Homo Sapiens and provided more direct evidence about ancient migration patterns that heretofore were the (somewhat) speculative province of paleolinguists (those who track cultural changes through the evolution of language (e.g. Indo-European roots of Modern English).
The most interesting work is still to come, with the ability to trace the migration of very ancient and relative recent peoples (e.g. Mongols, Huns, Goths, Norse) I suspect it will become clearer that the differences between modern Germans and modern French are relatively recent and thin. Ditto for Russians and Ukrainians, Bosniaks and Serbs, Iraqis and Iranians, etc.
Historians will thus have a new arrow in their quiver to puncture populist oversimplifications. It’s a tough sell. The Musk-eteer barging around Europe telling Germans that they have “too much of a focus on past guilt,” Putin is showing a dab hand at recharacterizing the national identity of Ukrainians, and nationalist/populists across the continent are eagerly omitting any mention of the complexities of their own national history. Here in the US, the rush to vocational training and underfunding of universities is making it difficult to get young people to wrestle with the messy stories of the past and various politicians are trying to legislate their version of the “truth.” Other “truths” (or at least equally plausible stories) are (as Al Gore said 19 years ago (!)) “inconvenient.” What happened in the first part of the 20C is not necessarily “repeating itself” these days, but it does look to be rhyming on multiple syllables.
As I suggested a few weeks ago, our modern world has gotten stuck in the first wave of institutionalization, of which national identity is a key component. The challenges raised by social sciences and humanities to this social self-construct have—so far—proved insufficient to turn the tide. It remains to be seen whether the addition of evidence from the “hard” sciences that will show in detail the similarity of so-called national identities will change minds.
Nationalism as a principal means of self-identification arose in the 19C under the pressures of globalization which showed the inadequacy of localities as a foundation for self. Concurrently, other modes-especially religion—were eroding. Thinking of oneself as Hanoverian or as Catholic no longer sufficed. Now, (with the exception of some Muslims, Hindus and Evangelicals) religion provides even less of an anchor to navigate a world beset with 24/7 global communication, instant translation, and culture that is increasingly indistinct. It took decades (centuries?) for nationalism to establish itself and the current transition—in which nationalism is the traditional and soon to be outmoded frame of reference—will not be any faster or less bloody.