Haplogroup I-M253

• 1. Introduction

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  Haplogroup I-M253, also called I1, is a branch of the male family tree that fathers pass to their sons. In Västra Götaland County in Sweden, 52 percent of men belong to it. In the province of Satakunta in western Finland, more than half do as well. Yet when researchers search ancient bones for the same lineage, they find it almost nowhere before the Nordic Bronze Age. So how does a line so scarce in the distant past become the signature of so many living Scandinavians? Where did it begin, who carried it, and how far did it travel? The answers come from a handful of ancient burials, some careful arguments over dates, and graveyards stretching from Poland to Spain.

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• 2. Scattered Early Traces

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  A hunter-gatherer buried in Spain around 11,466 BCE, labelled BAL051, carries one of the oldest known I1 signals. He belongs to a branch of I-Z2699 that has since died out. Geneticists think I1 split from its parent group as early as 27,000 years ago, in the Gravettian period. Yet as of November 2022, only six ancient samples older than the Nordic Bronze Age had been assigned to I1 at all.

  The next is SF11, found in the Stora Förvar cave on Stora Karlsö, an island off Gotland. He dates to about 7500 BC. He carried just 9 of the 312 mutations that define I1, so he sits on an extinct early branch. Because the skeleton lay in a cave, researchers could not link him to any archaeological culture.

  Farther south, a sample called BAB5 comes from Balatonszemes-Bagodomb in Hungary. It carried only 1 of those 312 mutations. Its date of 5600-4900 BC rests on archaeological context, with no radiocarbon test. A 2023 study of the same site found Langobard remains from the Migration Period, which casts doubt on that early date.

  Then come two men from Skåne in southern Sweden. RISE179 lay in a kurgan burial near Abbekås, dated to 2010-1776 BC in the late Neolithic Dagger Period. Oll009, buried near Öllsjö, dates to 1930-1750 BC. Both carried a high share of Western Steppe Herder ancestry and resembled Corded Ware populations.

  That pattern is the real puzzle. I1 is missing from early farmers in Neolithic Scandinavia, and SF11 is the only hunter-gatherer exception. It appears in notable numbers only when steppe-descended groups arrive, and it does not surge until the Bronze Age. Whether it hid among local foragers such as the Pitted Ware people, or came with incoming groups who picked it up elsewhere, remains unsettled. Researchers expect future finds to decide between those two origins.

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• 3. Dating the Common Ancestor

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  A 2010 study placed the origin of I-M253 between 3,170 and 5,000 years ago, in Chalcolithic Europe. In 2015, a new study used two techniques and got two windows: 3,470 to 5,070 years ago, or 3,180 to 3,760 years ago. Neither pinned down a single moment, but both landed in the Bronze Age neighborhood.

  Geography proved just as contested. A 2007 suggestion held that I1 first spread from the area that is now Denmark. Then Kenneth Nordtvedt of Montana State University weighed in, in a personal message in 2009 about the most recent common ancestor. He wrote: "We don't know where that man existed, but the greater lower Elbe basin seems like the heartland of I1".

  The newest figures come from Y-Full, which published results in January 2022. They put the formation of I1 at 27,500 years before present, with a 95 percent confidence range of 29,800 to 25,200. The most recent common ancestor of living carriers is placed at 4,600 years before present, within a range of 5,200 to 4,000. That fits a date near 2600 BC, and it places the man somewhere in Northern Europe.

  The branching pattern of the family tree tells its own story. It looks like a star, with many lines radiating from one point. That shape suggests I1 went from rare to common in one rapid burst. The extinct branches SF11 and BAB5 fall outside that burst, so they are not ancestors of any living man.

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• 4. The Bronze Age Burst

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  More than 99 percent of living I1 men belong to a single branch called DF29. All of them descend from one man born between 2500 and 2400 BCE, and the branch is estimated to have emerged in 2400 BCE. The oldest ancient individual found with DF29 is Oll009, the man from Skåne.

  The naming of branches changed in 2008. Before that year, the whole group was called I1a. That name was then reassigned to the DF29 branch itself. The other two primary branches are I1b, defined by S249 and Z131, and I1c, defined by Y18119 and Z17925.

  A 2024 study connected the burst to a movement of people around 2000 BC. According to its findings, I1 expanded during a migration from the eastern or northeastern parts of Scandinavia into Southern Sweden, Denmark and Norway. The migrants were associated with the introduction of stone cist burials, which are graves lined with stone slabs.

  The study tied this spread to a genetic cluster labelled "LNBA phase III". That cluster became the main ancestry source for Bronze Age, Iron Age and Viking Age Scandinavians. It also appears in other ancient European groups linked to Scandinavia or the Germanic world, such as the Anglo-Saxons and the Goths. The next chapters follow those groups as they left the north.

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• 5. Germanic Roads

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  Around 900 BC, Germanic tribes began leaving southern Scandinavia and northern Germany for the lands between the Elbe and the Oder rivers. Between 600 and 300 BC, another wave crossed the Baltic Sea and settled along the Vistula. Their descendants formed the Wielbark culture, which is associated with the Goths. I1 follows the same routes, along with certain subgroups of R1b and R1a. Researchers link it to the proto-Germanic speakers of the Nordic Bronze Age. Before the Migration Period, it was close to nonexistent in most of Europe outside Scandinavia and northern Germany.

  The burial site at Kowalewko in Poland dates to the Roman Iron Age. In 2017, Polish researchers recovered Y-DNA results for 16 people buried there. Eight belonged to I1, and three of those carried I-Z63, specifically the subclade I-L1237. That subclade may serve as a genetic marker for the Gothic tribe of late antiquity.

  In Germany, a 2015 study tested 12 people from Saxony-Anhalt who lived between 300 and 400 AD. Eight of them were I1. That matches the historical movement of Germanic tribes from Scandinavia into central Europe.

  The trail then runs south. I1-Z63 turns up at Collegno in Italy, in a cemetery of the late 6th century holding Goth and Lombard remains. It also appears at Crypta Balbi in Rome, with the subclade I-Y7234, where excavators found material linked to the Lombards.

  The farthest outpost is Pla de l'Horta, a villa near Girona in Spain. Nearby tombs show a Visigothic origin in their grave goods and design. A 2019 study sampled a few of the people buried there, and one carried I1. That result fits a shared ancestry for the Visigoths and the Ostrogoths.

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• 6. Across the North Sea

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  Out of 120 samples from Anglo-Saxon period England, 41 belonged to I1. That is roughly 34.17 percent, according to a 2022 study. The authors noted a strong link between I1 and a Continental North European ancestry they labelled "CNE". The Anglo-Saxon settlement of Britain, in this picture, brought the lineage to the islands.

  The debate over how many migrants came is older than the ancient DNA. In 2002, Michael Weale and colleagues reported a markedly higher level of I1 in England than in Wales. They read this as evidence of a mass Anglo-Saxon invasion from northern Germany and Denmark. Their model required an event affecting 50-100 percent of the Central English male gene pool of that time.

  They were careful about what the data could not show. It could not separate a simple addition to the local population from one where local men were displaced or reduced in number. Their sharpest conclusion was about borders: "a political boundary can be more important than a geophysical one in population genetic structuring".

  In 2003, Christian Capelli and colleagues sampled Great Britain and Ireland on a grid. They found a smaller gap between Welsh and English samples, with I1 fading gradually westward across southern Britain. Their results pointed to heavy Norwegian Viking influence in the north of the British Isles. English and mainland Scottish samples both showed German and Danish influence.

  The Viking Age brought a second wave. A 2020 study by Margaryan and colleagues analyzed 442 individuals from the Viking world. I-M253 was the most common Y-haplogroup among them. Norwegian and Danish Vikings carried more of it to Britain and Ireland. Swedish Vikings took it to Russia and Ukraine, and added more to Finland and Estonia.

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• 7. Living Carriers

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  Today the national averages tell the story of the north. About 38-39 percent of Swedish men carry I-M253, compared with 37 percent of Norwegian men and 34.8 percent of Danish men. Icelandic men come in at 34.5 percent, and Finnish men at about 28 percent. The lineage turns up in nearly every place the Norse reached. Settlement from Europe also planted it in the United States, Australia, New Zealand and Canada.

  In his 2006 book Blood of the Isles, Bryan Sykes gave the group, and its notional founding patriarch, the name "Wodan".

  Genealogy and testing have tied many famous names to the lineage. Birger Jarl, Duke of Sweden and founder of Stockholm, had his remains exhumed and tested in 2002. Alexander Hamilton, Andrew Jackson and Robert E. Lee belong to it. So do Leo Tolstoy, Ludwig van Beethoven and the Icelandic poet Snorri Sturluson. The Mayflower passenger William Brewster and Plymouth governor William Bradford are on the list, as are the musician Sting and the actor Chris Pine.

  Some of the links run through medieval dynasties. Prince Sviatopolk the Accursed, a son of Vladimir the Great, belonged to I1-S2077. Birger Jarl's House of Bjälbo went on to provide three kings of Norway and one king of Denmark in the 14th century.

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