In two previous articles (see October 2020) I have explored the association between the I-Y33765 clade and the Cult of St Clement. It seems to me that this connection is noteworthy because the Clement hereditary surname which is shared by English men who are derived for the I-Y33765 mutation is generally considered to originate from the name of this early Christian martyr. During the initial phase of conversion of pagan Viking Scandinavia to Christianity the Cult of St Clement became associated with the ruling elites of Norway, Denmark and England. Clement had been Pope during the first century, and was subsequently martyred by being thrown into the Black Sea tied to a ships anchor. This method of martyrdom appears to have made him a fitting patron for Viking societies whose existence depended on seafaring, maritime trade and naval prowess.
In England, as inherited surnames became adopted after the Norman Conquest, some followers of St Clement's cult seem to have adopted his name as their family name and so by the thirteenth century it is found as a patrilineal surname in several English counties. The dispersed nature of these early recorded instances of the name in England may perhaps suggest its adoption happened separately in different localities and so, as a surname, it became associated with unrelated Y-chromosome lineages.
The Y-chromosome and patrilineal surnames are inherited in a similar way and hence demonstrate an explicit correlation. In other words, Y-DNA and surnames can be used to demonstrate co-ancestry. In an early review of this correlation (King & Jobling,2009) populations of men with more common surnames showed greater Y-haplogroup diversity implying that common surnames in England were founded many times and hence contained lineages derived from many patriarchs. So, for the commonest English surname, Smith (652,500 holders), the Y-haplogroup diversity was very similar to that of the general population (see Figure 1a) whereas rare surnames, such as Attenborough (1,065 holders) were associated with a single haplogroup and may have had a single founder.
In England, these less common surnames that demonstrate clear evidence of co-ancestry have less than 5,600 holders (King & Jobling,2009). The Clement surname and its close spelling variants (Clements, Clemens, Clemons) is significantly more frequent than this co-ancestry threshold figure (in 2002 Clement variants had 24,200 holders in England, Wales and the Isle of Man) and consequently it has a Y-haplogroup diversity which is very similar to that found in the English male population (see Figure 1b).
From Figure 1(b) we can estimate that one in four men with the Clement surname in England and the USA are likely to have an I haplogroup Y-chromosome and one in five will probably be haplogroup I2a. As we know, in England, the Clement/s descent cluster originating from the Chew Valley, Somerset, is part of the I-Y33765 clade which itself is a small descendant branch of the I2a haplogroup (see Table 1).
Table 1: The I2a haplogroup. The table shows the descendant haplogroups within I2a leading to I-Y33765. Age estimates are calculated using the method used by Adamov et al.,(2015)
At FTDNA (May 2021) the I2a Haplogroup Project has 3917 members who are each derived for the I-P37 mutation which defines the I2a haplogroup. Within this sample of I2a men, 303 (approximately 8%) have tested positive for the much more recent Y4252 mutation which is immediately upstream from Y33765 (see Table 1). Using this information, we can calculate (100 / 8) * 5, and so suggest that fewer than one in sixty men with the Clement surname are likely to have an I-Y4252 haplogroup.
Now at this stage it seems to me only proper to make it absolutely clear that the method I am using to make this guesstimate is very "rough and ready". Even so, it does I think allow me to illustrate how the molecular genetics of the Y chromosome can lead us to identify a small population as a descent cluster even in a genetically diverse group like English men with the relatively common Clement/s family name. As mentioned earlier, in 2002 in England there were 24,200 holders, both men and women, with Clement variant names. So we can suppose that about 12,100 / 60 men in England may have an I-Y4252 Y chromosome; so perhaps we are considering just 200 or so men. Given the much larger threshold below which descent clusters have been shown in groups of men sharing an unusual surname (<5,600 holders) it would seem reasonable to assume the I-Y4252 Clement men in England will probably represent descent from a single founder.
From the evidence we have at present all the I-Y4252 Clement/s men with English ancestry are also derived for the downstream Y33765 mutation and have co-ancestry from the Chew Valley, Somerset. It seems to me this strongly suggests a single founder for the I-Y33765 Clement/s descent cluster and that he probably lived in what is now NE Somerset. Since we know that the Y33765 mutation formed in Scandinavia during the Iron Age it seems logical to look for reasons why a Scandinavian man might be fathering sons in NE Somerset towards the end of the first milenium. Not surprisingly this brings us back to the several manors in north Somerset that are mentioned as being owned by "the Dane" in the Domesday Book (Lewis, 2016), and in particular to the manor in the Chew Valley owned by Thorkil "the Dane" at Clutton.
References
Adamov, D., Guryanov, V., Karzhavin, S., Tagankin, V., Urasin, V. (2015) Defining a
new rate constant for Y-chromosome SNPs based on full sequencing data.
Russian Journal of Genetic Genealogy 1:3–36
King, T.E.,Jobling, M.A.(2009) What's in a name? Y chromosomes, surnames and the genetic genealogy revolution. Trends in Genetics 25, 351-360
Lewis, C.P. (2016) Danish Landowners in Wessex in 1066, in Danes in Wessex, Eds Ryan Lavelle & Simon Roffey, Oxbow Books, p 172-211
