Haplogroup I-Z63, also known as I1a3 per the International Society of Genetic Genealogy ('ISOGG), is a Y chromosome haplogroup. It is correlated with a DYS456 value inferior to 15, but there are exceptions.
I-Z63 is most common in England, Scotland, Germany, Fennoscandia and Poland. Its progenitor is assumed to have lived in Jutland at around 2500 BCE. Within Fennoscandia, I-Z63 has a particularly strong association with Finland. To date, ancient I-Z63 has been found archeologically in the Jutland area of Schleswig, Germany along with Poland and Italy.
Origins
On the basis of analysing samples of volunteers in YDNA sequencing, the YDNA analysis company YFull estimated that I-Z63 formed 4,600 years ago (2600 BC) (95% CI 5,100 <-> 4,000 ybp) with a TMRCA (Time to Most Recent Common Ancestor) of 4,400 years (95% CI 4,900 <-> 3,900 ybp) before present.
Geographically I-Z63 is believed to have arisen in or near what is now Denmark (based in part on the current distribution of this haplogroup). The current distribution of I-Z63 shows that there is a very high concentration of I-Z63 on the British Isles. At the same time, the archeological record presents a strong association of I-Z63 to the Wielbark culture and by extension with the Goths. There is a proposed link between the Goths and British migration, the so-called "Jutish Hypothesis". The "Jutish hypothesis" claims that the Jutes may be synonymous with the Geats of southern Sweden or their neighbours, the Gutes. The evidence adduced for this theory includes:
primary sources referring to the Geats (Geátas) by alternative names such as Iútan, Iótas and Eotas; Asser in his Life of Alfred (893) identifies the Jutes with the Goths (in a passage claiming that Alfred the Great was descended, through his mother, Osburga, from the ruling dynasty of the Jutish kingdom of Wihtwara, on the Isle of Wight), and; the Gutasaga (13th Century) states that some inhabitants of Gotland left for mainland Europe; large burial sites attributable to either Goths or Gepids were found in the 19th century near Willenberg, Prussia (after 1945 Wielbark in Poland).
The Jutes invaded and settled in southern Britain in the late 4th century during the Age of Migrations, as part of a larger wave of Germanic settlement in the British Isles. The Jutish migration to Britain may explain the high concentration of I-Z63 found in modern Britain. However, I-Z63 is notably sparse among modern volunteer testers from Denmark. This is surprising because, in a geographical sense, Denmark encompasses the ancient homeland of the Jutes. Foreign invaders displacing the Jutes from their ancient homeland may explain the relative lack of I-Z63 in Denmark. Even in the year 945, the peoples of Jutland were threatened by foreign invaders (yet ironically were posing a threat to other groups elsewhere, such as in England). In 945 King Hacon of Norway arrived in Jutland and slew many of the people there, sending the survivors “far up into the land”. The current distribution of I-Z63 clearly shows that while there is a near absence of I-Z63 in modern Denmark, sizable numbers of I-Z63 men live today in Finland, Norway, Sweden and Aland.
Based on the combined evidence, the preferred current working hypothesis puts the progenitor of I-Z63 in ancient Jutland around the year 2000 BCE.
Archeological Record
An individual with the subclade of I-Y21381 was found just south of Denmark in the Schleswig Rathausmarkt excavation in Schleswig, Schleswig-Holstein, Germany. This city on the Jutland peninsula is the successor to the important Viking settlement of Hedeby, which was destroyed in 1066. Sample SWG007 was obtained from grave 179 and dated to 1070-1140 CE.