FamilyTreeDNA "Discover" and TMRCA estimates for I-Y33765

In previous articles I have discussed Time to Most Recent Common Ancestor (TMRCA) estimates for the phylogenetically important mutations in our I-Y33765 clade and how we can calculate these time intervals using the mutation rate of SNP and STR Y-DNA genetic markers. Being able to calculate approximate TMRCA is obviously a great benefit when we are researching the supposed historical context of events involved in our genealogy. 

One characteristic of the types of calculations we have used for obtaining TMRCA intervals is that these have relied upon either SNP-only or STR-only methods. It has been reported (Balanovsky, 2017) that while experimentally obtained SNP marker mutation rates largely overlap and produce usable TMRCA estimates for both genealogy and evolutionary studies, STR markers are more useful when constructing fine-scale phylogenies that are typically associated with genealogical pedigrees. However both types of marker have their own inherent problems. when they are used as the basis for TMRCA estimations. 

First, when using SNP markers to estimate periods within the genealogical timescale it is important to take care to select only the very high confidence mutations. Unfortunately these may not always be available or easy to identify with confidence.  Because genealogical timescales are relatively short, the omission or addition of just a single SNP can significantly alter estimates. Next, when using STR markers the major difficulty is presented by convergent and/or multiple mutations which can introduce error that again can be hard to identify with confidence, especially when a small number of individuals are being compared.  

For these reasons, the confidence intervals provided for our estimates are poor and there is a consequent need for an alternative method to estimate TMRCA that would give improved accuracy.  In 2021, a paper was published in Genes by Iain McDonald (McDonald, 2021) in which he presented a novel mathematical approach that combines probability calculations based on using SNP and STR markers with other probabilities derived from historical data and from ancient DNA to achieve more precise and accurate TMRCA intervals for genealogy.  

Earlier this month (July 2022) FamilyTreeDNA announced the release of an online feature they call "Discover" that provides "information about the haplogroup from your Y-DNA test".  The application is available to FTDNA customers and to others who simply need to register with that company. The tool allows users to input a Y-DNA haplogroup designation from which the application generates report pages which give a summary of relevant information, including geographic frequency, notable related individuals, migration routes and ancient DNA examples.  In addition, a section called "scientific details" gives options that list the base variants associated with that haplogroup, show its position within the Y-DNA haplotree and, most importantly for our interests, provide an estimation of the TMRCA at various confidence levels.  In presenting this latter feature (see Figure 1) the page rubric explains that it "is calculated based on SNP and STR test results from many present-day DNA testers" and "the state-of-the-art FamilyTreeDNA algorithm for inferring age estimates for the Y-DNA Haplotree. [was] Developed together with Iain McDonald."   

It seems to me this description and the helpful credit provide an indirect but clear reference to the combined probability model Iain McDonald describes in detail in his paper mentioned above.  As a result I think it worth briefly mentioning the significant advantages shown in McDonald's work now that we can all make use of the user-friendly version of his algorithm as it is provided by the FTDNA application.

In his paper McDonald describes the mathematical basis for a method which merges "the Y-SNP and Y-STR molecular clocks, and takes into account other available evidence (eg:, ancient DNA, proven paper genealogies, relatedness through autosomal DNA, etc)."  He demonstrates his revised algorithm using four examples.  In three scenarios he generates data which illustrate DNA ancestry either in colonial America, or in historical Scotland and Ireland, or medieval or prehistoric Europe and for the fourth model he uses real data from royal Stuart lineages.  With each of these example data sets he illustrates how his combined method gives improvements in the precision and accuracy of the TMRCAs compared to either STR-only or SNP-only methods.  

McDonald writes that "the most significant improvements in the precision of the TMRCAs come from the ability to combine both STR and SNP mutations into a single calculation" and he notes that in the future, improving the definition of STR and SNP mutation rates, offers the greatest likelihood for getting further benefits from his combined method over either STR-only or SNP-only TMRCA calculations.

Figure1: FamilyTreeDNA Discover presentation of TMRCA probability for I-Y33765

 

So it seems these advantages and possibilities are very encouraging, especially now that we all have easy access to an online tool that produces TMRCA periods based on this McDonald combined probability model.  

 

Now let us turn to how these developments may help our I-Y33765 research. When we compare the previously calculated SNP-only TMRCA estimates for the haplogroups within our clade with those produced using the FamilyTreeDNA "Discover" app. (Table 1) we can see it has provided some useful improvement.

Table 1: Comparison of TMRCA estimates for haplogroups within the I-Y33765 clade

At present within our clade we only have two haplogroups, I-Y33761 and I-BY198548, for which the dates are known from documentary sources. When we compare the "Discover" TMRCA estimates for both of these haplogroups with those obtained using our normal SNP-only methodologies (Table 1) there are improvements in the precision and accuracy achieved for both.  It seems to me that this is the most obvious practical method by which to judge the new FTDNA algorithm and based on this result I consider the new methodolgy is definitely helpful.  

In addition, the 95% confidence interval for the "Discover" estimates is significantly more constrained compared with the YFull SNP-only method.  Lastly, the mean dates given by the "Discover" application are broadly similar to those we have obtained using our clade-specific SNP mutation rate that we calculated directly from the nineteen generation Nils Swensson (1631-1713) pedigree. Because of these several positive indicators I have updated our draft I-Y33765 chart (Figure 2) using the TMRCA dates highlighted in Table 1.  As you can see the majority of these are taken from the FTDNA "Discover" application.

 Figure 2: I-Y33765 draft chart, July 2022 

(Click on images and table to enlarge)

References

Balanovsky, O (2017) Toward a consensus on SNP and STR mutation rates on the human Y-chromosome, Human Genetics, 136, 575-590

McDonald, I. (2021) Improved models of Coalescence Ages of Y-DNA Haplogroups, Genes, 12, 862 

I-Y33765 and ancient DNA - 5680-13 (VK22)

Only two ancient DNA samples with Y-DNA identified as haplogroup I-L233 or one of it's downstream clades have been published.  Both these samples were found in areas that border the Baltic Sea which makes them especially interesting for us given the apparent modern locus of I-Y33765 in south eastern Sweden.  In the previous article I considered the older of these specimens, an I-L233, late mesolithic adult male known as "Spiginas 1" that was excavated in Lithuania in 1985.  In the present notes I want to concentrate on the much younger specimen, originally catalogued as "5860-13" but more recently designated "VK22", an I-A8462 12th century adult male that was excavated in 1938-40 in north-western Russia.

The archaeological context of "5680-13" (Figure 1) is particularly interesting and has been extensively reviewed by Evgeniy L.Nosov and his colleagues (2018).  Although their book is written in Russian each chapter contains a helpful and comprehensive summary in English. In Chapter 3, Nadezhda Platonova and Serafina Sankina report and discuss excavations of an elite Christian cemetery adjacent to the Church of St Clement at Zemlyanoye Gorodishche  (Earthen Hillfort), Staraya Ladoga, Russian Federation.  In the late 1930's, the individual "5680-13" was one of 65 skeletons recorded from this cemetery when it was first excavated by a team led by Vladislav I Ravdonikas and Grigoriy P Grozdilov.  In 1941, the physical anthropologist Alexander N Yuzefovich was the first to observe "The strikingly Norse features of the 11th century skeletons sharply differentiate the Staraya Ladoga series from the Slavonic ones". The significance of his observations concerning a possible Scandinavian origin for the individuals buried at St Clement's church has, during the past decade, been internationally investigated (Magaryan et al.,2020; Douglas Price et al., 2019). All the skeletons recovered from the cemetery are now part of the collection of the Peter the Great Museum of Anthropology and Ethnography (Kunstkamera), St Petersburg, Russian Federation.   

Figure 1: Location of skeleton "5680-13" (VK22) in the southern half of the medieval cemetery of St Clement church at Zemlyanoye Gorodishche, Staraya Ladoga, Russian Federation. (a) Relationship of Staraya Ladoga settlement (red icon) to Lake Ladoga and to the Baltic Sea (b) The Kremlin and earth hillfort. Red rectangles represent the approximate position of the 11th century St Clement church and its cemetery.  Cross symbol indicates approximate burial location of individual "5680-13" (VK22).   (c) Map of excavation sites at Zemlyanoye Gorodishche. (Source of site plan Fig.B7, Nosov et al., 2018). [Click on image to enlarge]

The pre-World War II excavations by the team of Ravdonika and Grozdilov indicated that the cemetery had been used over many decades and that, at least in part, those interred there represent a quite distinct population. The earliest graves were in the southern part of the cemetery and had been dug in rows.  These graves contained men aged under thirty years together with some children and infants but adult female burials were notably absent.  In contrast the layout of the more recent graves in the northern part of the cemetery was irregular and in this part of the cemetery the skeletal remains included both sexes. Throughout the St Clement cemetery all graves suggested a Christian burial rite with almost no grave goods.  Typically individuals lay on their backs with heads to the west.  Radio carbon dating of bone samples indicates burials began in the eleventh century. 

During the medieval period, in the Ladoga region adjacent to the River Volkhov, a significant Viking age trade emporium developed. This was because the river was part of one of the major routes linking Scandinavia with the Black Sea and eastern Roman Empire.  From historical sources we are told that in 1019, when Yaroslav the Wise, Grand Prince of Kiev married the daughter of King Olav of Sweden their alliance resulted in the "Ladoga Jarlsdom" passing to Ragnvald Ulfsson who was the grandson of Skagel Toste (909-975).  Skagel Toste has been linked by some writers with the Toste or Tusti mentioned as taking Danegeld in England on the U344 runestone at Orkesta in Vallentuna near Stockholm. Although this appears an interesting idea it seems to me this connection is unlikely as the period from 954-980 saw little Viking raiding in England and no large payments of tribute are recorded.  However, returning to our main narrative, documentary evidence shows that Jarl Ragnvald was in fact permanently exiled from the Swedish court to Staraya Ladoga with his entire household and retinue.  It is conjectured (Nosov et al., 2018) that some male members of the Jarl's comitatus may be represented among the burials at St Clement.  Certainly men who came with Jarl Ragnvald may have had  Christian beliefs and it is possible that the cemetery was the place where such warriors were buried.  Snorri Sturlusson recounts in the Heimskringla that Ragnvald and his guards were involved in conflict with endogenous pagan tribes.   

Whatever his true background, the "5860-13" individual was buried among the distinctive population of young male skeletons from the southern half of the cemetery (see Figure 1b & c). Based on his long bones his body length has been estimated at between 166 and 169.3cm and this compares with an average for the cemetery "warrior" group of 170.6-172.6cm. It has been observed that this is appreciably taller than the height of the modern Russian population in the Ladoga region (Nosov et al., 2018). 

In a recent molecular genetics study (Magaryan et al.,2020), individual "5680-13" was one of seventeen burials from the St Clement cemetery that were used to characterize Viking age population genomics. In this investigation skeleton "5680-13" was given the sample ID, "VK22".  Ancient DNA extracted from the "VK22" skeleton confirmed his Y-DNA haplogroup as I-A8462.  In the modern European male population this haplogroup has so far only been identified in the British Isles and more particularly in Scotland and the northern half of Ireland (Figure 2).  In view of earlier comments about the putative origins of men buried at Zemlyanoye Gorodishche it seems possible that his Y-DNA haplogroup could imply "VK22" grew up in the northern British Isles and subsequently traveled, possibly via Sweden, to Staraya Ladoga where he served in the guard of a prince of the Rus.  Such a biography would demonstrate the potential mobility of Y-DNA during the Viking age and it would also emphasize that the find location of a marker obtained using ancient DNA may differ significantly both from its historical origin and from the region of its prevalence in modern populations.

Figure 2: Distribution of I-A8462 in modern male populations in Europe and the British Isles (Source: https://phylogeographer.com, June 2022)

In a further recent paper (Douglas Price et al., 2019) the authors used strontium isotope analysis to show that about one third of the individuals (n=5) from the southern part of the St Clement cemetery who they tested (n=15) are first-generation migrants likely from central Scandinavia or another area with very high 87Sr/86Sr values (Figure 3).  All this "Scandinavian" group had strontium ratios well above 0.7150. In contrast, individual "5860-13" showed 87Sr/86Sr values that were almost the lowest of any in the sample examined.  Douglas Price et al.,(2019) suggest the burials with values below 0.7150 may either indicate local individuals or individuals from Gotland both of whom may have grown up eating terrestrial and marine food from the Baltic.  Although the authors say "at present, we are unable to resolve this question" they conclude that "all (or many) of these individuals are non local [to Staraya Ladoga] and all (or many) of the individuals in this study would be from Sweden or Gotland".  Given the prevalence of I-A8462 in the British Isles and particularly in Scotland, it seems to me, it can be argued that individual "5680-13" more likely grew up in the British Isles since his strontium values are also consistent with those for that area which range between 0.07078 and 0.7165 (Evans, Chenery & Montgomery, 2012).  Hence it seems to me the combination of Y-DNA haplogroup and strontium isotope estimates make it likely the "5680-13" man was a first-generation migrant from the northern British Isles.  

Figure 3: Strontium isotope value for individual "5680-13" (second blue bar from left) compared with fourteen other burials at St Clement cemetery (blue bars). (Source: Figure 9 from Douglas Price et al., 2019). The estimate shown for the I-A8462 individual "5680-13" falls within the range of strontium isotope values recorded in the British Isles, i.e: 0.07078 - 0.07165, when using samples of tooth enamel from archaeological sites.

So, in the context of our interest in ancient DNA samples that are phylogenetically close to the I-Y33765 clade, the recent studies on the "5680-13" skeleton from Staraya Ladoga have illustrated the potential during the Viking period for male movement from the British Isles into the eastern Baltic Sea. Hence, it is as if "5680-13" had used a "return ticket" for the journey we conjecture must have been taken by the patriarch of the English arm of I-Y33765, from Sweden to Somerset, at about the same time.

In addition, it seems to me, the proximity of the "5680-13" burial to a church dedicated to St Clement is yet another, somewhat whimsical, coincidence.  As I have discussed several times already the cult of St Clement has been shown to have particular significance for the Scandinavian ruling elites of the Viking Age (Crawford, 2008). To illustrate this point from the perspective of the "5680-13" burial in the cemetery at Zemlyanoye Gorodishche I think it well worth quoting from the English summary to Chapter 3 of the review of those excavations (Nosov et al., 2018), written by Platonova and Sankina in which they observe: -  

"The consecration to the name of Pope St Clement also confirms that the first church was built as early as the 11th century. In the times of Vladamir and Yaroslav, St Clement still was considered as the main heavenly protector of the Rus'.  However, already as early as the 12th century, the cult of St Clement as the first saint associated with the Rus' is ousted by the cult of St Andrew the First-Called. In Rus' of the 12th-13th century, practically no stone temples dedicated to St Clement are known. Ladoga is nearly [the] single exception".   

References

Crawford, B.,(2008)., The Churches Dedicated to St. Clement in Medieval England. A Hagio-geography of the Seafarer´s Saint in 11th Century North Europe. St. Petersburg: Axioma, 237 pp.

Douglas Price,T, Moiseyev,V, & Grigoreva, N., (2019)., Vikings in Russia: origins of the medieval inhabitants of Staraya Ladoga,  Archaeological and Anthropological Sciences, https://doi.org/10.1007/s12520-019-00897-2 

Evans,JA, Chenery, CA, & Montgomery, J., (2012), A summary of strontium and oxygen isotope variation in archaeological human tooth enamel excavated from Britain, Journal of Analytical Atomic Spectrometry, 27, 754-764

Margaryan, A., et al., (2020)., Population genomics of the Viking world, Nature, 585, 390–396. https://doi.org/10.1038/s41586-020-2688-8

Nosov,EN, Platonova,NI, Beletsky,SV, Kirpichnikov,AN, Kurbatov,AV, Lapshin,VA, Milyaey,PA, & Sankina,SL (2018)., Advance in Archaeology of Staraya Ladoga: materials and studies, Proceedings of the Russian Academy of Sciences, Institute for the History of Material Culture, Vol. LIII, Neva Book Publishing House, St Petersburg, Russian Federation, 536pp

 

I-Y33765 and ancient DNA - Spiginas 1

Most of what we know about the I-Y33765 clade is based on interpretation of results from Y-DNA samples taken from ten men. Four of these men live in England, and another four in Sweden.  The two remaining DNA donors both have family origins in England but their nineteenth century ancestors migrated either to the United States or to New Zealand.  An obvious, but very important, characteristic of all these men is that, when their DNA samples were collected they were all living.  In other words their Y-DNA is modern.  

In previous articles I have used results of their Y-DNA analysis and details of their documented genealogies to speculate on the geographic origins of the I-Y33765 clade.  In particular, I have used the genealogies of the four modern Swedish men to support a narrative in which I have linked the Viking age patriarch of our clade to the south eastern part of present-day Sweden and more specifically to the area of Tjust.  While it seems to me such speculation is helpful and productive it's credibility rests on the unproven assumption that the places of residence of the ancestors of modern Swedish Y-DNA donors during the seventeenth century will be approximately localised in the area inhabited, 1000 years earlier, by their shared Viking age patriarch.  Without some additional evidence that seems a large leap of faith.

Obviously, it would be very nice to have an ancient DNA sample from Sweden that is derived for Y33765, but the expense and difficulties of finding, extracting and sequencing ancient DNA make the existence of such optimal evidence rather improbable.  At present only two ancient DNA samples with Y-DNA identified as haplogroup I-L233 or one of it's downstream clades have been published; "Spiginas 1", an I-L233 late mesolithic adult male excavated in Lithuania in 1985 and "5860-13" (also known as VK22) an I-A8462 12th century adult male excavated in north-western Russia in 1938-40.  At first glance, a feature common to these specimens, and especially interesting in the context of the apparent modern locus of I-Y33765 in Sweden, is that both were found in regions that border the Baltic Sea. 

Figure 1: Geographic and phylogenetic relationship between Spiginas1, 5680-13 (VK22) and I-Y33765  

In this and the next article I intend to examine the published archaeology of both these I-L233+ men and see how this may help us test our present hypothesis that I-Y33765 originated in south-eastern Sweden.  

First, it seems appropriate to consider the older ancient DNA sample Spiginas 1.  This is the designation given to a 6000y old Mesolithic or Sub-Neolithic I-L233+ male hunter-gatherer excavated from a small cemetery in Western Lithuania in 1985-86.  His grave was closely grouped with three others (Spiginas 2, 3 & 4) on the former island of Spiginas in the marshy southern part of Lake Birzulis.  In the southeastern Baltic region there are no large stone-age burial sites and human remains are instead found singly or in small cemeteries, as at Spiginas and another island cemetery in Lake Birzulis, Duonkalnis, where 14 graves were excavated in 1985.  At Spiginas the four burials were on the summit of a glacial kame formation at an elevation of 163m above sea level and their radiocarbon date estimates span more than 4000 years (7780ybp, Kunda culture, Spiginas 4 to 3580ybp, Neolithic corded ware culture, Spiginas 2).  Two papers (Butrimas, 1992; Balcione, Cesnys & Jankauskas, 1992) describing the original archaeological investigations are written in Lithuanian and each has an English and Russian summary.

Figure 2: Mesolithic sites in the area of Birzulis Lake (from original paper by Butrimas,1992).

1, the sites of Swiderian culture; 2, early Mesolithic sites of Pulli type of the Kunda culture; 3, sites of the Middle and the Late Mesolithic; 4, sites of the early Mesolithic sites of Pulli type and of the Late Mesolithic; 5, sites of undetermined chronological determination; 6, Mesolithic graves; 7. Stray find location of bone point of Kunda type.  Sites: 1. Kulnikas   2. mesolithic graves of Spiginas island   3. Spigino sala   4. Spigino Ragas   5. Oznagaris1   6. Oznagaris2   7. Oznagaris3   8. Birzulio Sasmauka   9. Birzulio Sasmauka2   10. Dreniai   11. Lingenai   12. Duonkalnis   13.

According to the excavation report English abstract (Butrimas, 1992) the grave of Spiginas 1 "was destroyed during World War II, and only fragments of long bones and a skull have preserved. Two flint arrow heads of early Kungemosen microlith type were found among these bone fragments".  Translation of the Lithuanian text of Butrimas, 1992, dealing with the Spiginas 1 grave confirm that as a result of the war-time disturbance "fragments from this grave were dispersed over a fairly large area - 4 x 4m, but mainly within the presumed grave site. Blurred contours of the grave pit is exposed at a depth of 45-48cm.  In the pit two romboid flint (cross) arrowheads [see Figure 4]. At the north-east boundary of the grave was a small pebble covered in brownish ochre. Three more small ochre patches were observed in various areas of the grave [see Figure 3]. North of the grave there was a recent shell hole and disturbed ground.  Material from the grave pit was given to the Moscow Institute of Geological and Geochemistry Isotope Geochronology Laboratory (USSR).  The grave dated from 5020 +/ -200 ybp, 3070 +/- 200BC.  This radiocarbon date suggests that the grave is early Neolithic.  However, arrowheads and grave No4 date suggests this date underestimates the true age. Anthropologists believe that a 35-45y old man is buried."

Figure 3: Spiginas 1 grave situation plan (from original paper by Butrimas,1992). 1 - bone fragments  2 - flint  3 - ochre covered pebble  4 - ochre  5- disturbed ground  6 -  grave outline  (after Figure 3 from Butrimas, 1992.  Although no scale is specified in the original paper it seems possible that the plan represents the 4 metre by 4 metre area over which “fragments from this grave were dispersed”)

Figure 4: The two early Kungemosen microlith type rhomboid flint arrowheads from Spiginas 1 grave pit (Figure 5 from Butrimas, 1992).  These appear to have been “grave goods” but could possibly be the cause of injury or death of Spiginas 1?  The only source of flint in the Eastern Baltic is in Estonia and this is very poor in quality (Tringham, 1971, page 60)

Figure 5: Drawings of the two flint points from the Spiginas 1 grave pit. (Figure 10 from Ostrauskas, 1996)

The second original paper (Balcioniene, Cesnys & Jankauskas, 1992) gives more detail on the skeletal remains of Spiginas 1.  From the English summary,“In Grave 1 a male,35-45 years old, was buried.  Craniometric analysis was impossible; teeth were abrased to the 3^rd – 4^th degree.  M¹  had four tubereles and was quite massive.  Oesteometrical data are presented in Tabes 3 – 7.  No pathological changes were identified”.  Transaltion of the Lithuanian text indicates that “of the skeleton there remained a left maxillery fragment, right radial shaft, the right ulna, without the distal end of the femoral shaft, the distal end of the left tibia shaft, right and left fragment of the fifth metatarsal. …… tooth wear is consistent with a 35-45 year old".

Mittnik, A et al. (2018) use Spiginas 1 as one of ten samples representative of the Narva culture that occupied the eastern Baltic region from the late Mesolithic to the Middle Neolithic (Baltic EMN Narva).  They report his Y chromosomal haplogroup is I which they further refine to I2a1a2a1a based on L233:G→A (2x) (see their Supplementary Information, Supplementary Note 3. They also report he has one upstream mutation for haplogroup I2a1a2a (L1286: G→A at 1x) and one mutation for I2a1 (PF4004: T→C at 1x) and I2a (L460: A→C at 1x).  In addition they determined his mitochondrial DNA haplogroup was H11a (see their Table 1) and they note that while this haplogroup is “normally associated with the Neolithic expansion into Europe, but (he) shows no evidence of Neolithic farmer ancestry on the nuclear level suggesting that this haplogroup might have been present already in foraging groups”.  The woman who founded the H11a mitrochondrial haplogroup lived between 8000 and 4200 ybp (Behar et al., 2012).

Figure 6: Frequencies of four selected Y haplogroups in ancient DNA samples from Europe (from original paper by Jobling & Tyler-Smith, 2017).  The dark blue line shows the decline in haplogroup I2 from its significant proportion of the male population during the Mesolithic to a possible nadir approximating to the late Bronze age.

So, based on radiocarbon dating and the flint grave goods we can infer that Spiginas 1 lived in a late Mesolithic or early Neolithic hunter-gatherer society centered on Lake Birzulis.  Butrimas (2017) has speculated on the basis of archaeological, linguistic and historical evidence that the northern part of this lake represents a ritual complex of cemeteries, sacrificial hearths and funerary feast sites which date from the middle Mesolithic period to historical times.  He considers the four graves at Spiginas to be part of this ritualistic landscape.

At the time Spiginas 1 was buried at lake Birzulis the I2 Y-DNA haplogroup constituted a significant proportion of the European male population (see Figure 6).  The decline in haplogroup I2 from about 3000BC has been linked with the migration of populations from the Eurasian steppe which introduced significant cultural and genetic replacement, including R haplogroup Y-DNA (principally R1b) into central and western Europe and eventually the British Isles (Olalde et al., 2018).  In Scandinavia these migrations are characterized by the Corded Ware Culture (CWC) (also termed Battle-Axe Culture within Scandinavia) which in this region notably introduced R1a Y-DNA (Mittnik et al., 2018; Gunther et al., 2018) 

However, for the ancestral narrative of our I-Y33765 clade in SE Sweden, the significant neolithic culture is associated with the indigenous Scandinavian Hunter Gatherers (SHG).  These SHG peoples are derived from a mixture of Western (WHG) and Eastern Hunter Gatherer (EHG) populations (Gunther et al., 2018) in which the dominant male haplogroups are G and I2.  The Narva culture, of which Spiginas 1 is a member are genetically closer to WHG than EHG and hence Spiginas 1 can be considered genetically related to SHG men.

Within south eastern Sweden, Denmark and Estonia CWC sites are more usually associated with inland locations and with herding and farming while the SHG sites are typically coastal and involve a mobile maritime lifestyle that is called the Pitted Ware Culture (PWC).  The nomenclature "corded" or "pitted" refers to decorative characteristics of the pottery produced by the respective cultural groups.  The principle food source for PWC populations were seals and fish, giving them a nickname as "Inuit of the Baltic".  A recent study (Coutinho et al., 2020) of twelve male skeletons from three PWC sites on the island of Gotland was able to characterize the Y-DNA for eight of the individuals and each belonged to haplogroup I2.  Fifty percent of the total sample (n=6) were confirmed as haplogroup I2a (I-CTS595).  The radiocarbon dates for these individuals are estimated within the range 3000-2500 yBCE and so are not dissimilar to that quoted for Spiginas 1.  Also like the Spiginas grave PWC burial rituals involve single individual graves and include the use of red ochre.

Gotland is about 100km from the Swedish mainland but slate arrow points, found in some PWC graves on the island, seem to substantiate contact with mainland sources to obtain this material.  During the past century PWC sites have been recorded at many coastal locations bordering the Baltic (see Figure 7).  In Tjust, Smaland, Sweden, (see Figure 8) PWC sites have been excavated, at Hellero and Gardsholmens, north of Vastervik.  Finds from Vivastemala, which is just to the south of Vastervik have been important in interpreting Pitted Ware pottery in south-east Sweden because the styles found there in the late 1930's were very similar to those found at PWC sites in east central Sweden (Papmehl-Dufay, 2006).  Clearly, because of their maritime lifestyle, PWC populations would have appreciated the opportunities offered by the Tjust archipelago.   

Figure 7: Pitted Ware Culture (PWC) sites in Southern Scandinavia (after Douglas Price, 2015)

After about 2800yBCE there is archeological evidence for cultural contacts between CWC and PWC so that from about 2400yBCE, the PWC becomes absorbed into the late CWC or Battle Axe Culture (BAC). Further sources have suggested that the resulting Nordic Bronze Age population was the progenitor for the Germanic tribes which dispersed throughout Europe during the Migration Period.  

 

Figure 8: Pitted Ware sites in the Tjust archipelago

In summary, the Spiginas 1 individual is a representative of hunter-gatherer societies of the Baltic region.  His genomic DNA seems closer to WHG rather than EHG populations and his I2 Y-DNA haplogroup is found at high frequencies in pre-Neolithic samples from Europe but becomes progressively less common from the early Neolithic onward.  The coastline of south east Sweden was home to the last humans to adopt a hunter-gather lifestyle in Europe, the PWC, who had a mobile maritime lifestyle.  Genetic analysis of male PWC graves on Gotland shows a high frequency of the I2a Y-DNA haplogroup throughout the Neolithic. Several PWC sites have been excavated in the Tjust archipelago. 

References

Balcioniene, I.,Cesnys, G & Jankauskas, R.,(1992) Craniometry, Odontology, Osteometry and Paleopathology of the Mesolithic graves from Spiginas, Lietuvas Archeologia, v8,  p10-16

Behar, D.M. et al (2012) A “Copernican” reassessment of the human mitochondrial DNA tree from its root.  American J of Human Genetics, 90(4), 675-684

Butrimas, A (1992) Mesolithic Graves from Spiginas, Lietuvos Archeologia, v8,  p4-9

Butrimas, A (2017) From Mesolithic to Early Christianity: The development of the ritual Complex in the northern part of Lake Birzulis (Lithuania) according to archaeological, linguistic and historical research. Sociology and Anthropology, 5, 204-219

Cesnys, G.,Butrimas, A., (2009) Reinventing Mesolithic skulls in Lithuania: Donkalis and Spiginas sites.  Acta Medica Lituanica, 16, 1-8

Coutinho, A.,Gunther,T.,Munters,A.R.,Svensson,E.M.,Gotherstrom,A.,Stora,J.,Mailmstrom,H., & Jakobsson, M. (2020) The Neolithic Pitted Ware culture foragers were culturally but not genetically influenced by the Battle Axe culture herders. American Journal of Physical Anthropology, 172, 638-649

Douglas Price, T (2015) Ancient Scandinavia, OUP, Oxford, 494pp

Gunther, T et al. (2018) Population genomics of Mesolithic Scandinavia: Investigating early post-glacial migration routes and high-latitude adaption.  PLOS Biology, 16, e2003703, https://doi.org/10.1371/journal.pbio.2003703

Jobling, M.A & Tyler Smith, C (2017) Human Y-chromosome variation in the genome sequencing era. Nature Reviews Genetics, 18, 485-497

Mittnik, A et al. (2018) The Genetic Prehistory of the Baltic Sea region, Nature Communications

Ostrauskas, T. (1996) The Mesolithic in Western Lithuania, Lietuvos Archeologia, v14,  p192-212

Papmehl-Dufay, L. (2006) Shaping an Identity. Pitted Ware pottery and potters in southeast Sweden. Theses and Papers in Scientific Archaeology 7, Stockholm University, Sweden, 329pp

Trinham, R.(1971) Hunters, Fishers and Farmers of Eastern Europe 6000-3000 BC, Hutchinson University Library, Hutchinson & Co, London