There would seem to be something remarkable about the man who was the founder of the I-Y4252 haplogroup. We can see this clearly from the explosive expansion of his clade. At present (September 2023) there are 22 named immediately downstream branches (Figure 1) plus four others that are, as yet, not named. This proliferation of branches suggests he must have sired many children and that his sons, likewise, inherited his prodigous libido. Even so, to explain the exceptionally vigorous expansion we see among his immediate male descendants, this above-average rate of reproduction is not enough; some other qualities made these men unusually successful and powerful within their society. In this article, I want to consider what attributes and advantages the founder, his sons and grandsons, may have possessed that enhanced their genetic success.
From the results of over 200 Big Y tests, the FTDNA "Discover" algorithm calculates a mean estimate for the most recent common ancestor (MRCA) date of the I-Y4252 haplogroup as circa 50CE with a robust 95% CI 300BCE-300CE and hence we can have reasonable confidence that the founder lived during the Roman Iron Age (Figure 3). Where he lived is more difficult to establish, but the modern distribution of descendant clades across north-western Europe, including the British Isles, makes it seem probable he lived among the barbarian tribes somewhere to the north of the Rhine and Danube and to the west of the Vistula. In addition, it would seem probable that his homeland was no further north than southern Scandinavia, possibly in those areas now comprising Denmark and southern Sweden (Figure 2).
Figure
2: The geographic origin of I-Y4252 is likely within an area spanning
Scandinavia and north-western Europe in parts of the present-day nations of Holland, Denmark, Germany, Sweden, and Poland.
In 50CE, Tacitus called most of this region Germania, and he was able to name and describe the character and customs of many Germanic clans that inhabited this area. One characteristic he reported was that among these Germanic peoples, monogamy was the general rule for familial relationships, but that this custom was not followed by their leaders and chiefs. He commented that among these elite males, polygamy (Todd, 1980, p30) and concubinage (Karras, 2006, p145) were frequently encountered. This observation may help us add a significant detail to our picture of the I-Y4252 founder and his family. For males of most species, including humans, the primary limit on their reproductive success is their access to fertile females, so, multiple wives and concubines could certainly favour the expansion we see in the founders line. Hence, to begin our quest, I would suggest the I-Y4252 patriarch was very likely part of the Germanic elite, possibly the leader of a barbarian clan in Germania, at the time when Roman hegemony dominated the known world.
Next, we should ask what it was that conferred success on a barbarian leader in Germania at this time. Across Europe, the Iron Age saw this new, extremely versatile metal utilised primarily to increase militarism and warfare, which, in Germania especially, fostered a culture of the warrior. Adding this detail to our picture of the I-Y4252 founder, we see a man who is dominant among his male affiliates, who very likely were a gang of effective violent killers with the aid of whom he could repeatedly slaughter or subjugate neighbouring competitors. To remain dominant in such a society, a warlord would need to satisfy the greed of his close subordinates and perhaps his wider clan by providing them with wealth, gained either as plunder from defeated enemies or as protection payments from vassal groups (Steuer, 2006). Here it is worth emphasising that the closest and most potent source of wealth for any barbarian tribe at this time would have been the global hegemon, Rome, and so we might expect a significantly successful Germanic warlord to have interactions, either of confrontation or more probably, allegiance, with the Roman state. Many Germanic warrior groups worked for Rome as foederati during this period, and it seems to me that the I-Y4252 founder may well have been the leader of such a band.
Hence, from these observations, we define our I-Y4252 founder as a man who is part of the elite within barbarian Germanic society and a leader of professional warriors who enjoy sustained and successful interactions with Imperial Rome. These interactions allow the founder and his associates to increase their wealth and status through diplomacy or military force, using treaties, plunder, and trade. During the first and second centuries CE, the homeland of this aristocratic leader would be in north-west Europe or southern Scandinavia. By comparing this draft curriculum vitae with the archaeology of these regions during the early Roman Iron Age, it seems to me we may be able to identify a more precise locus for the founder's heimat.
Figure 3: Chronology for the proliferation of clades downstream from I-Y4252. These genetic branches appear to have formed in the three centuries between the Macromanic Wars (160-180CE) and the end of the western Roman Empire (476CE). This suggests that the increasing instability along the northern border of the Roman Empire at this time favoured the reproductive success of I-Y4252 (+) males. It is also noteworthy that this period overlaps with the Volkerwanderung of the Germanic people. Formation dates (CE, shown in square brackets) for the following 18 downstream clades have been used in the boxplot: FT94277 [71], ZS9184 [97], A10033 [144], FTA13235 [166], BY82831 [186], BY117344 [193], A7111 [208], A19385 [198], A19485 [237], Y32655 [263], FGC56815 [357], Y33765 [408], BY65456 [428], FT132671 [478], A417 [538], FTC68462 [672], FT303575 [696], BY50578 [1068]. (Click on the image to enlarge)
During the Iron Age, among the Germanic tribes, wealth and status were demonstrated in elaborate funeral practices, and the archaeology associated with these death rituals provides a large and informative source of evidence on the role and relationships of their ruling class. Elite cremations or burials were often memorialised using mounds containing boats, animals, war gear, and all manner of luxury items such as jewellery, glassware, ornaments, and gaming or musical parphenalia. On the largest Danish island of Sjælland (Zealand), near the town of Stevns, the site at Himlingøje (Figure 4) is significant in this respect (Grane, 2011). It contains a large number of burials, apparently of all social classes but most notably including elite graves dating from the period 150-250CE (Storgaard, 2003). It is worth observing that this timespan correlates well with our MRCA date estimates based on modern genetic sampling for the expansion below I-Y4252 (Figure 3).
At least thirteen of these elite graves contain luxury Roman imports and gold items that display wealth and power on a greater scale than any other site in Scandinavia at the time. The earliest of these so-called "princely" graves are marked by mounds. On excavation, two of the mounds contained no obvious human remains and are consequently considered cenotaphs, each memorialising an aristocrat whose body was not available for burial, perhaps because he or she died in a distant location or at sea. Possible support for this hypothesis may come from a third mound that contained a dismembered corpse of a young male. This man almost certainly died in a place very distant from Himlingøje and is considered to have been dismembered so as to facilitate his transport for burial in that special cemetery. These practices and similarities between object placements in these elite burials, together with the length of time over which the site was in use, have been interpreted as showing that Himlingøje is the burial place of an aristocratic ruling dynasty with truly "international" connections.
Figure
4: Hypothetical expansion of I-Y4252 during the 1st millennium. The
present-day distribution of I-Y4252, based on the self-declared ancestry
of tested men, shows the majority consider their known direct-male
ancestry originates in the British Isles, but the clade is also present
at lower density throughout western Europe. a) Expansion from the
supposed birth location of the I-Y4252 founder, circa 50CE [dashed
ouline]. Indicative routes and dates are a hypothetical model and should not be interpreted as anything more. b) Imported Roman glass "circus" cup from an elite grave at Himlingøje, Sjælland (Zealand), Denmark, 2-3rd century [National Museum of Denmark] c) Map of western Baltic showing location of Himlingøje cemetery d) Grave mounds at Himlingøje. (Click on the image to enlarge)
While I would not claim this site has any direct link with the I-Y4252 founder and his immediate decendants, it seems to me that the Himlingøje burials do exemplify the existence of a widely travelled and connected aristocratic class of a type that would have been both neccessary and capable of producing the proliferation of a genetically distinct male lineage in north-western Europe during the Imperial Period.
The Himlingøje cemetery also shows that such an aristocratic dynasty had become established in the islands of the western Baltic and that its control over power was maintained for several generations. This location implies the population very likely had a maritime tradition and was consequently capable of moving warriors, imigrants, or trade goods, including slaves, along the Baltic and North Sea coastlines. In particular, such seamen may have ventured to and from the British Isles. For me, this would be a very important attribute because of the association of many I-Y4252 descendant clades with modern British men. In addition, the only two ancient DNA, Y4252-derived samples, so far identified (Lakenheath 6 & Groningen 2), were excavated in eastern England and Holland. Both of these locations are consistent with ancestral migrations from the western Baltic. Lakenheath 6 is the older of the two and is apparently a second-generation immigrant from NW Europe who was buried in a 5th century Anglo-Saxon cemetery in Suffolk. Consequently, it seems reasonable to me that the Danish islands could well represent territories in which our I-Y4252 founder flourished.
The rich burials at Himlingøje also coincided with significant changes in relations between Imperial Rome and Germania that began during the second century CE. From the time of the prolonged rebellions against Rome, which occurred along the upper Danube and which are known as the Macromannic Wars (166-180CE), Germania became increasingly unstable (Todd, 2001). Using the MRCA date estimates for the majority of branches immediately below I-Y4252, it would seem to have been during the next couple of centuries that further significant expansion of that clade occurred. We may imagine that this would have been a conducive environment for the proliferation and dispersal of a warrior dynasty where instability and lawlessness favoured men bred to a culture of movement, opportunistic violence, and greed.
In all this speculation, I have not attempted to define the ethnicity of the I-Y4252 founder other than generalising that he was likely a Germanic barbarian. This omission is quite intentional because the meaning of Germanic clan, tribal, and ethnic labels in the second and third centuries is difficult to verify. These names and the affiliations or locations to which they apply seem to me to represent a dangerously "movable feast", depending on the source reference consulted, and so they have the potential to muddle and mislead. It seems to me this is because the ethnic composition of such groups was fluid and diverse, and I further suggest descendants of the I-Y4252 patriarch would have become mingled and mixed among Batavian, Alammani, Eruli, Saxon, or Danes as opportunity and necessity demanded. My evidence for this conclusion is the extensive present-day distribution of descendant clades in western Europe, Scandinavia, and the British Isles. When taking this into account, I think it is fair to say that the supposed wanderings of no single Germanic group can have broadcast our patriarch's seed so widely (Figure 4).
In phylogenetic trees, nodes at which more than two branches occur are said to be polytomic, but the causes of polytomy in the human Y-chromosome are unclear. In several previous articles, I have noted that Poznik et al. (2016) have shown that technological innovations can cause advantages to male groups and thus produce an explosive increase in the number of men carrying a certain Y-DNA haplogroup. Resulting male social elites can retain such reproductive advantage for generations. Dr Chris Tyler-Smith of the Wellcome Trust Sanger Institute, who led the 1000 Genomes Project, which supplied the data for the 2016 Poznik Nature Genetics paper, has stated that such rapid, star-like haplogroup bursts during the recent evolution of the human Y-chromosome likely "resulted from advances in technology that could be controlled by small groups of men. Wheeled transport, metalworking and organised warfare are all candidate explanations".
In previous articles, I have suggested that in the case of I-Y4252, mounted cavalry warfare and clinker built, iron rivet shipbuilding may be examples of such innovations during the first millennium. Is it too fanciful to imagine that, when charging into a skirmish mounted astride a warhorse equipped with saddle, stirrups, and bridle, or again, when holding the steering-board of a shallow-drafted, clinker built sailing ship covertly entering some foreign river estuary, the I-Y4252 "skill set" that I have proposed would use its opportunistic elan to gain control and establish dominance amongst unforeseen adversity?
In summary, it is my hypothesis that our I-Y4252 founder was a successful warrior and leader who lived in north-western Europe or southern Scandinavia during the Roman Iron Age. He and his immediate descendants were part of an "international" elite class that ruled the Germanic tribes during much of this period. The exceptional reproductive success of the founder and his male descendants, exemplified by the rapid genetic and geographic expansion of the I-Y4252 clade, was facilitated by polygamy and concubinage and also by technologies that enhanced both their movement and repeated success in warfare. In turn, their priveledged status and wealth were increased by their ability to develop and sustain diplomatic, military, and trading interactions with Imperial Rome.
References
Grane, T. (2011), Zealand and the Roman Empire, 101-111, In:The Iron Age on Zealand: Status and Perspectives Ed. Linda Boye, Royal Society of Northern Antiquaries pp308
Karras, R.M. (2006), The history of marriage and the myth of Friedelehe, Early Medieval Europe, 14 (2), 119-151
Poznik, G.D. et al. (2016) Punctuated bursts in human male demography inferred from 1244 worldwide Y-chromosome sequences. Nat. Genet. 48(6), 593-599
Steuer, H. (2006) Warrior Bands, War Lords, and the Birth of Tribes and States in the First Millennium AD in Middle Europe 227-236, In: Warfare and Society, Archaeological and Social Anthropological Perspectives Eds Otto, T., Thrane, H., Vandkilde, H. Aarhus University Press
Storgaard, B. (2003) Cosmopolitan aristocrats. pp 106-125, In: The spoils of victory: The North in the shadow of the Roman Empire, Eds. Jørgensen,L., Storgaard,B. & Gebauer,L . The National Museum, Copenhagen.
Todd, M. (1980), The Barbarians - Goths, Franks and Vandals, 184pp, B.T. Batesford Ltd, London, UK
Todd, M. (2001), Migrants & Invaders, 160pp, Tempus Publishing Ltd, Stroud, UK
