The Greeks are important because Western civilization began with Greece. And therefore modern civilization. I don’t think the Greeks were “Western” truly; my own preference is to state that the West as we understand it is really just Latin Christendom, which emerged in the late first millennium A.D. in any coherent fashion. Yet without Classical Greece and its accomplishments the West wouldn’t make any sense.
But here I have to stipulate Classical, because Greeks existed before the Classical period. That is, a people who spoke a language that was recognizably Greek and worshipped gods recognizable to the Greeks of the Classical period. But these Greeks were not proto-Western in any way. These were the Mycenaeans, a Bronze Age civilization which flourished in the Aegean in the centuries before the cataclysms outlined in 1177 B.C.
The issue with the Mycenaean civilization is that its final expiration in the 11th century ushered in a centuries long Dark Age. During this period the population of Greece seems to have declined, and society reverted to a more simple structure. By the time the Greeks emerged from this Dark Age much had changed. For example, they no longer used Linear B writing. Presumably this technique was passed down along lineages of scribes, whose services were no longer needed, because the grand warlords of the Bronze Age were no longer there to patronize them and make use of their skills. In its stead the Greeks modified the alphabet of the Phoenicians.
To be succinct the Greeks had to learn civilization all over again. The barbarian interlude had broken continuous cultural memory between the Mycenaeans and the Greeks of the developing polises of the Classical period. The fortifications of the Mycenaeans were assumed by their Classical descendants to be the work of a lost race which had the aid of monstrous cyclops.
Of course not all memories were forgotten. Epic poems such as The Iliad retained the memory of the past through the centuries. The list of kings who sailed to Troy actually reflected the distribution of power in Bronze Age Greece, while boar’s tusk helmets mentioned by Homer were typical of the period. To be sure, much of the detail in Homer seems more reflective of a simpler society of petty warlords, so the nuggets of memory are encased in later lore accrued over the centuries.
When antiquarians and archaeologists began to take a look at the Bronze Age Aegean the assumption by many was that the Mycenaeans were not Greek, but extensions of the earlier Minoan civilization. The whole intellectual history here is outlined in Michael Wood’s 1980s documentary In Search of the Trojan War. But suffice it to say that many were shocked when Michael Ventris deciphered Linear B, and found that it was clearly Greek!
The surprise here was partly due to the fact that though Mycenaean cultural remains indicated a different civilization from that of the Minoans, its motifs clearly inherited from the earlier group. Mycenaeans seemed in many ways to be Minoans in chariots. And the presumption has long been that the Minoans themselves were not an Indo-European group. In fact, the island of Crete had developed early on and become part of the orbit of civilized states from the northern Levant down to Egypt, including Cyprus. Therefore some scholars hypothesized an Egyptian connection.
In any case, the Mycenaeans were Greek. And Homer then most certainly must have transmitted traditions which went back to the Bronze Age.
At this point we can now speak to demographics with some data, as Nature has come out with a paper using ancient DNA from Mycenaeans, Minoans, as well as Bronze Age Anatolians, Genetic origins of the Minoans and Mycenaeans:
The origins of the Bronze Age Minoan and Mycenaean cultures have puzzled archaeologists for more than a century. We have assembled genome-wide data from 19 ancient individuals, including Minoans from Crete, Mycenaeans from mainland Greece, and their eastern neighbours from southwestern Anatolia. Here we show that Minoans and Mycenaeans were genetically similar, having at least three-quarters of their ancestry from the first Neolithic farmers of western Anatolia and the Aegean1, 2, and most of the remainder from ancient populations related to those of the Caucasus3 and Iran4, 5. However, the Mycenaeans differed from Minoans in deriving additional ancestry from an ultimate source related to the hunter–gatherers of eastern Europe and Siberia6, 7, 8, introduced via a proximal source related to the inhabitants of either the Eurasian steppe1,6, 9 or Armenia4, 9. Modern Greeks resemble the Mycenaeans, but with some additional dilution of the Early Neolithic ancestry. Our results support the idea of continuity but not isolation in the history of populations of the Aegean, before and after the time of its earliest civilizations.
About 85% of the ancestry of the Minoan samples could be modeled as being derived from Anatolian farmers, the ancestors of the “Early European Farmers” (EEF) that introduced agriculture to most of the continent, and whose heritage is most clear in modern populations among Sardinians. For the three Mycenaean samples the value is closer to 80% (though perhaps high 70s is more accurate).
Now the question though is what’s the balance? For the Minoans the residual is a component which seems to derive from “Eastern Farmer” populations. Additionally the authors note that the Y chromosomes in four out of five individuals in their Mycenaean-Minoan-Anatolians are haplogroup J associated with these eastern groups, rather than the ubiquitous G2 of the earlier farmer populations. The authors suggest that in the 4th millennium B.C. there was a demographic event where this ancestral component swept west, and served as the common Mycenaean-Minoan (and Anatolian) substrate.
But the Mycenaean samples (one of which was elite, two of which were not) also have a third component: affinities with steppe populations. One model which presents itself is that there was a pulse out of the Balkans, and this was part of the dynamic described in Massive migration from the steppe was a source for Indo-European languages in Europe. But another model, which they could not reject, is that the steppe affinity came from the east, perhaps from a proto-Armenian population. Additionally, they did not find much steppe ancestry in the Anatolian samples at all.
My own preference is for a migration through the Balkans. It seems relatively straightforward. As for why the Anatolian samples did not have the steppe ancestry, the authors provide the reasonable supposition that Indo-European in Anatolia branched off first, and the demographic signal was diluted over successor generations. Perhaps. But another aspect of Anatolia is that it seems the Hittites, the Nesa, where never a numerous population in comparison to the Hatti amongst whom they lived. Perhaps a good model for their rise and takeover may be that of the post-Roman West and the Franks in Gaul.
Then the question becomes how does a less numerous people impose their language on a more numerous one? This happens. See the Hungarians for an example. In fact the paper which covered the other end of the Mediterranean, The population genomics of archaeological transition in west Iberia: Investigation of ancient substructure using imputation and haplotype-based methods, suggests that language shift can occur in unpredictable ways. On the one hand Basques seem to have mostly Indo-European Y chromosomes, but their whole genome ancestry indicates less exogenous input than their neighbors. Speaking of which, we know by the Classical period large regions of western Spain were dominated by Celtic speaking peoples, but the genetic imprint of the Indo-Europeans is still very modest in the Iberian peninsula.
I think what we’re seeing here is the difference between Indo-European agro-pastoralists arriving to a landscape of relatively simple societies with more primal institutions, and those who migrated into regions where local population densities are higher and social complexity is also greater. This higher social complexity means that external elites can takeover a system, as opposed to an almost animal competition for resources as seems to have occurred in Northern Europe.
Finally, at the end of the supplements there is an analysis of the physical features of the Minoans and Mycenaeans. There’s not much that’s surprising. The Minoans and Mycenaeans were a dark haired and dark eyed folk. Why should this surprise us at all? We actually have self representations of them! That’s what they look like. If anything they were darker than modern Greeks (small sample size means power to draw conclusions is not high). Why?
Two reasons that come to mind: natural selection, and the fact that modern Greeks seem to be shifted to continental Europeans to their north, likely due to migration. My number one contender here are the Scalveni Slavic tribes which pushed into much of Greece in the second half of the 6th century A.D. (though a minority of Greek samples I’ve seen don’t exhibit much skew toward Slavs at all).
In the future with more samples and more genomes we’ll know more. But I think this work emphasizes that when it comes to Europe most of the demographic patterns we see around us date to the Bronze Age or earlier.