Haplogroup I-M253

Haplogroup I1 is believed to have been present among Upper Paleolithic European hunter-gatherers as a minor lineage but due to its near-total absence in pre-Neolithic DNA samples it cannot have been very widespread.

Neolithic I1 samples are very sparse as well, suggesting a rapid dispersion connected to a founder effect in the Nordic Bronze Age.

[26][27] A 2024 study found that I1-M253 expanded rapidly during a migration from the eastern or northeastern parts of Scandinavia into Southern Sweden, Denmark and Norway around 2000 BC and was associated with the introduction of stone cist burials.

While haplogroup I1 most likely diverged from I* as early as 27,000 years ago in the Gravettian, so far DNA studies have only been able to locate it in three Paleolithic and Mesolithic hunter-gatherers.

As of November 2022, only 6 ancient DNA samples from human remains dating to earlier than the Nordic Bronze Age have been assigned to haplogroup I1: Despite the high frequency of haplogroup I1 in present-day Scandinavians, I1 is completely absent among early agriculturalist DNA samples from Neolithic Scandinavia.

[14] However, Prof. Dr. Kenneth Nordtvedt, Montana State University, regarding the MRCA, in 2009 wrote in a personal message: "We don't know where that man existed, but the greater lower Elbe basin seems like the heartland of I1".

Since the most up-to date calculated estimation of TMRCA of I1 is thought to be around 2600 BC, this likely puts the ancestor of all living I1 men somewhere in Northern Europe around that time.

[47][48] Current DNA research indicates that I1 was close to non-existent in most of Europe outside of Scandinavia and northern Germany before the Migration Period.

[51][52] The cemetery is dated to the late 6th Century and further suggests that I1-Z63 and downstream subclades are linked to early Medieval Gothic migrations.

[53] Additionally, I1-Z63 was found in the Late Antiquity site Crypta Balbi in Rome, this time with the downstream subclade I-Y7234.

The Pla de l'Horta villa near Girona in Spain is located in close proximity to a necropolis with a series of tombs associated with the Visigoths.

During the modern era, significant I-M253 populations have also taken root in immigrant nations and former European colonies such as the United States, Australia, New Zealand and Canada.

They saw this as convincing evidence of Anglo-Saxon mass invasion of eastern Great Britain from northern Germany and Denmark during the Migration Period.

The main claim by the researchers was that an Anglo-Saxon immigration event affecting 50–100% of the Central English male gene pool at that time is required.

This study shows that the Welsh border was more of a genetic barrier to Anglo-Saxon Y chromosome gene flow than the North Sea ...

Map of the early Nordic Bronze Age, where I1 first became prominent. The Nordic Bronze Age is often considered ancestral to the Germanic peoples.
A timeline of the early Germanic expansions
Map showing the distribution of Y chromosomes in a trans section of England and Wales from the paper " Y Chromosome Evidence for Anglo-Saxon Mass Migration ". The authors attribute the differences in frequencies of haplogroup I1 to Anglo-Saxon mass migration into England, but not into Wales.
Distribution of Y chromosome haplogroups from Capelli et al. (2003). Haplogroup I-M253 is present in all populations, with higher frequencies in the east and lower frequencies in the west. There appears to be no discrete boundary as observed by Weale et al. (2002)
DNA example: strand 1 differs from strand 2 at a single base pair location (a C >> T polymorphism).