Haplogroup I2 (Y-DNA)
Contents
1. Geographic distribution
2. Subclades
3. Origins & History
3.1 I2a1 (P37.2)
3.1.1 I2a1a (M26)
3.1.2 I2a1b (M423)
3.2 I2a2 (P216)
3.2.1 I2a2a (M223)
3.2.2 I2a2b (L48)
3.3 I2b (L416)
3.4 I2c (L596)
4. Famous I2 individuals
Geographic distribution
Haplogroup I2 is the most common paternal lineage in former Yugoslavia, Romania, Bulgaria and Sardinia, and a major lineage in most Slavic countries. Its maximum frequencies are observed in Bosnia (55%, including 71% in Bosnian Croats), Sardinia (39.5%), Croatia (38%), Serbia (33%), Montenegro (31%), Romania (28%), Moldova (24%), Macedonia (24%), Slovenia (22%), Bulgaria (22%), Belarus (18.5%), Hungary (18%), Slovakia (17.5%), Ukraine (13.5%), and Albania (13.5%). It is found at a frequency of 5 to 10% in Germanic countries.
Subclades
The phylogenetic tree of I2 evolved a lot over the last 7 years and top-level subclades were renamed more often than for any other haplogroup except R1b. To avoid all confusion it is recommended to double-check the defining mutations (SNP's) when reading older studies or making references to a particular subclade.
I2* (M438/P215/S31)
I2a (L460)
I2a1 (P37.2)
I2a1a (CTS595)
I2a1a1 (M26)
I2a1a1a (L672)
I2a1a1a1 (L160)
I2a1a1a1a (PF4088)
I2a1a1a1a1 (CTS11338)
I2a1a1a1a1a (Z105)
I2a1a1a1a1a1 (Z118)
I2a1a1a1a1a1a (Z106)
I2a1a1a1a1b (PF4189)
I2a1a1a1a1b1 (PF4398)
I2a1a1a1b (F1295)
I2a1a1a1b1 (PF6950)
I2a1a2 (L880)
I2a1a3 (L1286)
I2a1b (M423)
I2a1b1 (M359.2/P41.2)
I2a1b1a (L147.5)
I2a1b1a1 (P41.2/M359.2)
I2a1b2 (L161.1/S185)
I2a1b3 (L621/S392)
I2a1b3a (L147.2)
I2a1c (L1286)
I2a1c1 (L1287)
I2a1c1a (L233/S183)
I2a1d (L880)
I2a1e (L1294)
I2a1e1 (L1295)
I2a2 (S33/M436/P214)
I2a2a (M223)
I2a2a1 (M284)
I2a2a1a (L1195)
I2a2a1a1 (L126/S165, L369)
I2a2a1a2 (L1193)
I2a2a2 (L701)
I2a2a2a (P78)
I2a2a2b (L699/L703)
I2a2a2b1 (P704)
I2a2a3 (Z161)
I2a2a3a (L801/S390/Z76)
I2a2a3a1 (P95)
I2a2a3a2 (Z78)
I2a2a3a2a (L1198)
I2a2a3b (L623)
I2a2a4 (L1229)
I2a2a4a (Z2054)
I2a2a4a1 (L812/S391)
I2a2a4b (L1230)
I2a2a5 (L1228)
I2a2b (L38/S154)
I2a2b1 (L533)
I2b (L416)
I2c (L596)
Origins & History
I2 (M438/P215/S31) is thought to have originated during the Late Paleolithic, around the time of the Last Glacial Maximum, some 22,000 years ago. Its region of origin is undetermined at present. It could have been one of the Last Glacial Maximum refugia or somewhere in Anatolia or around the Caucasus. Three hypotheses are consequently possible.
The first scenario is that I2 originated in Europe. When the ice sheets started receding to the north from 20,000 to 12,000 years ago, the I2 hunter-gatherers re-expanded from their LGM refugium and colonised vast parts of western, central and Eastern Europe. In this hypothesis I2 would be associated with mtDNA haplogroups H1, H3, U5 and V, among others.
In the second scenario I2 originated in West Asia, but also colonised Europe when the ice sheets receded. In this hypothesis I2 would be mostly associated with mtDNA haplogroups J and T.
In the third and least likely scenario, I2 originated in West Asia but did not come to Europe until the Neolithic. There seems to have been several independent migrations of Neolithic farmers and herders from the Middle East to Europe, bringing lineages such as G2a, E1b1b, J and T. It is not yet clear at present whether each group brought only one or perhaps two haplogroups, or whether most migrations already comported blends of many haplogroups. In this hypothesis I2 could be associated with mtDNA haplogroups N1a, R, HV, H (various subclades), J, T, K and X.
In the two first cases I2 would have been absorbed by Neolithic farmers in Southeast Europe (M423), Central Europe (P214, L596), and the western Mediterranean (M26). The relative success of specific branches of I2 seem to be linked to the diffusion of agriculture. The south-western I2a1a (M26) branch was absorbed by Neolithic farmers of the Printed-Cardium Pottery culture (5000-1500 BCE), whose descendants are found mostly in modern Sardinians and Basques. The eastern I2a1b (M423) is probably linked to the Cucuteni-Trypillian culture (4800-3000 BCE), which was the most advanced Neolithic culture in Europe before the Indo-European invasions in the Bronze Age. In contrast, central, northern and Western European I2 lineages (such as L38, M223, L1286, L1294 and L880) only survived at low frequencies. The reason could be that I2 hunter-gatherers adopted agriculture too late and were not numerous when the wave of Indo-European took over central, northern and Western Europe (=> see R1b history).
Haplogroup I2a1 (P37.2)
Haplogroup I2a1 is by far the largest branch of I2 and the one most strongly linked to Neolithic cultures in south-east, south-west and north-west Europe.
Distribution of haplogroup I2a1 (formerly I2a) in Europe
Haplogroup I2a1a1 (M26)
I2a1a (M26, L158, L159.1/S169.1) was known as I1b2 until 2005, I1b1b in 2006-7, and I2a1 from 2008 to 2010. It is found in all Western Europe, and reaches maximum frequencies among the Sardinians (37.5%) and the Basques (5%), two population isolates. M26 is geographically restricted to the British Isles, the Low Countries, France, western Germany, Switzerland, Sardinia, Sicily, the west coast of Italy, Iberia and the Mediterranean coast of the Maghreb. The only M26 negative for the L160 mutation are confined to Ireland.
I2a1a-M26 was probably one of the main paternal lineages of the Megalithic cultures of Western Europe during the Neolithic and Chalcolithic periods.
Haplogroup I2a1b (M423)
I2a1b (M423, L178) was known as I1b until 2007, and I2a2 from 2008 to 2010. The main subclade, representing over 90% of all M423 lineages is L621 and its subclade L147.2. The other subclades are L41.2 (very rare) and L161.1 (found mostly in Germany and the British Isles).
Haplogroup I2a1b-L621
This branch is found overwhelmingly in Slavic countries. Its maximum frequencies are observed among the Dinaric Slavs (Slovenes, Croats, Bosniaks, Serbs, Montenegrins and Macedonians) as well as in Bulgaria, Romania, Moldavia, western Ukraine and Belarus. It is also common to a lower extent in Albania, Greece, Hungary, Slovakia, Poland, and south-western Russia. I2-L621 (L147.2+) is also known as as I2a-Din (for Dinaric).
The high concentration of I2a1b-L621 in north-east Romania, Moldova and central Ukraine reminds of the maximum spread of the Cucuteni-Trypillian culture (4800-3000 BCE) before it was swallowed by the Indo-European Corded Ware culture. This could mean that the Cucuteni-Tripolye culture was a native European group of hunter-gatherers who adopted farming after coming in contact (with perhaps some intermarriages) with the Middle Eastern farmers who settled in the Balkans (haplogroups E1b1b, G2a, J2b and T). After being Indo-Europeanized, I2a-L621 would have become the dominant paternal lineage among southern Slavs, while R1a remained dominant among northern Slavs.
The presence of I2a-L621 in Romania and Bulgaria could be attributed to the migration of the ancient Dacians and Thracians, who emerged as a mixture of of indigenous peoples and Indo-Europeans (in this case, essentially R1a-Z280) sometime between 3300 and 1500 BCE. The Illyrians, who conquered the territory of former Yugoslavia circa 1200-1000 BCE, might have been an offshoot from the Dacians or the Thracians, or a closely related tribe from the Carpathian basin.
The second great expansion of I2a-Din took place with the Slavic migration in the Late Antiquity and Early Middle Ages. I2a-Din had started to mix with Proto-Indo-Euroepan R1a around Moldova, Ukraine, Belarus and Poland during the Corded Ware period (2900-2400 BCE), then disseminated more uniformly across Proto-Slavic tribes during the Bronze and Iron Ages. After Germanic tribes living in eastern Germany and Poland, like the Goths, the Vandals and the Burgundians, invaded the Roman Empire, the Slavs from further east filled the vacuum. Following the collapse of the Western Roman Empire in 476, the Slavs moved in the Dinaric Alps and the Balkans. By the 9th century the Slavs occupied all modern Slavic-speaking territories, apart from the eastern Balkans under the control of the Turkic-speaking Bulgars.
Nowadays northern Slavic countries have between 9% (Poland, Czech republic) and 21% (Ukraine) of I2a-L621, while southern Slavs have between 20% (Bulgaria) and 50% (Bosnia). The higher percentage of I2a-Din in the south owes to the cumulative effect of Bronze Age and Early Iron Age migrations (Dacians, Thracians, Illyrians) and the medieval Slavic migrations. The relatively high percentage of of I2a-L621 in non-Slavic people like the Hungarians (15% ), Albanians (12%) and Greeks (9%) dates from the Bronze Age and population movement inside the Roman Empire which redistributed I2a beyond the original Daco-Thracian and Illyrian territories. Based on these frequencies, and the distribution of R1a subclades, it can be assessed that the Daco-Thracians and Illyrians carried approximately two to three times more I2a-Din than R1a, while the Early Slavs must have had roughly twice more R1a than I2a-Din. The higher proportion of R1a in many northern Slavic countries today is due to earlier migrations of R1a during Bronze Age (such as L260 among West Slavs and Z92 and Z93 among Russians and Belarussians).
Haplogroup I2a1b-L161.1
Commonly known in genetic genealogy circles as "I2-M423-Isles", L161.1 is found at highest frequencies in western Ireland (5-10%) and the Scottish Highlands (1-5%), but is also found at low frequencies (> 1%) throughout Central and Western Europe, from Latvia, Lithuania and Belarus to the British Isles, and from Scandinavia to north-western Spain. It has also been found in Albania, northern Greece, Bulgaria and Romania.
Overall the distribution of I2a-L161.1 is somewhat reminiscent of the extent of Germanic migrations. Its close phylogenetic relation to I2a-L621 branch means that L161.1 was probably absorbed early by the Indo-European migrations too. Its higher concentration in western Poland and northern Germany hint at an absorption by the western sweep of the Corded Ware culture. Around 2400 BCE the Corded Ware culture in Germany, Bohemia and western Poland was overrun by the Unetice culture, which represents the advance of R1b branch of Proto-Indo-Europeans from Southeast Europe. From then on, I2a-L161.1 would have been able to spread to Western Europe with the Proto-Celts (most probably the R1b-L21 branch) and to Scandinavia with the Proto-Germanics (chiefly R1b-S21). That would explain why I2a-L621 seem to correlate with the distribution of R1b-L21 (like in Ireland, Scotland and Brittany) on the one hand, but also with all regions settled by Germanic people.
Haplogroups I2-L880, I2-L1286 and I2-L1294
These minor subclades are found at low frequencies mainly in north-Western Europe, especially in the British Isles, north-west France and northern Germany, but also in Switzerland and Scandinavia. Like I2a2 (see below) these lineages are probably the descendants of central and north-west European hunter-gatherers.
Haplogroup I2a2 (P214)
I2a2 (S33/M436/P214, P216/S30, P217/S23, P218/S32, L35/S150, L37/S153, L181) was known as I1c until 2005 and I2b until 2010. It is associated with the pre-Celto-Germanic people of north-Western Europe, such as the megaliths builders (5000-1200 BCE). The wide variety of STR markers within I2a2 could make it as much as 13,000 years old.
I2a2 is found in all Western Europe, but apparently survived better the Indo-European invasions (=> see R1b) in northern Germany, and was reintroduced by both the La Tène Celtic expansion (5th to 1st century BCE) and the Germanic invasions (3rd to 6th century CE). Nowadays, I2a2 peaks in central and northern Germany (10-20%), the Benelux (10-15%) as well as in northern Sweden. It is also found in 3 to 10% of the inhabitants of Denmark, eastern England, and northern France. It is rarer in Norway, except in the south, where the Danish influence was the strongest historically.
Distribution of haplogroup I2a2 (formerly I2b) in Europe
There are two major subclades of I2a2 : I2a2a and I2a2b, the former further subdivided in four subclades:
Haplogroup I2a2a (M223)
I2a2a (formerly I2b1) amounts to over 90% of I2a2.
I2a2a1 (M284+) occurs almost exclusively in Britain, where it seemingly developed about 3,000 years ago.
I2a2a2 (L701+) has a very wide distribution. It is found in all Central Europe from Germany and the former Austrian Empire to Poland, Romania and Ukraine, but also in lower frequencies in Greece, Italy, France, Spain, England, Ireland, and Armenia. It could have been disseminated in part by the Goths. It is conspicuously absent from Scandinavia and Scotland. L701+ matches the I2 Continental 3 clade at Family Tree DNA.
I2a2a3 (Z161+) is commonly known as the I2 Continental clade (except Continental 3). It is the largest of the four subclades of I2a2a and is found predominantly in Germanic countries, with a particularly high concentration in Denmark, Germany, the Netherlands, England and in Northwest Sicily (Norman settlement). It is also found at lower densities throughout the rest of Europe, from Portugal to Russia. I2-Z161 is thought to have been propagated around Europe by the Danish Vikings (Britain, Normandy, Sicily), the Swedish Vikings (Baltic, Russia, Ukraine), the Goths (Moldova, Balkans, Italy, south-west France, Spain), the Suebi (Portugal and Galicia), the Lombards (attested by a hotspot in Campobasso, Molise), and the Franks (Rhineland, Belgium).
I2a2a4 (L1229+) is typical of England, Normandy (and other parts of France) as well as central and northern Germany. It is also found among English surnames in Ireland, although not Norman ones (but rather Anglo-Saxon ones). Its much higher density in Germany and England than in Denmark or France, and its absence from Sicily, indicate that it is probably an Anglo-Saxon lineage rather than Norman/Viking.
Haplogroup I2a2b (L38/S154)
I2a2b (formerly I2b2) has a distribution mostly limited to Alpine Italy (esp. Piedmont), Switzerland, the German Rhineland, the Harz mountains, the Low Countries, eastern France, and the British Isles (with the exception of Cornwall, Wales, Cumbria and the Scottish Highlands).
Four out of the six samples from the 3000-year old Lichtenstein Cave in central Germany belonged to L38+. The cave was part of the Bronze Age Urnfield Culture. Based on the STR dating, it is believed that this lineage spread from Germany to England via Belgium in the Late Iron Age with the Celtic people of the La Tène Culture. I2a2b is therefore essentially a Alpine Celtic haplogroup.
The distribution of I2-L38 matches fairly well that of haplogroup R1b-U152 north of the Alps. Both haplogroups are also found at low frequency in Hungary, Romania, Bulgaria and central Turkey, probably reflecting the migration of La Tène Celts in the third century BCE (see map). R1b-U152 is associated with both the Central European Celts (Unetice, Urnfield, Hallstatt, La Tène) and the Italic people. I2-L38 being limited to the Alpine region in Italy, mostly the north-west where Gaulish tribes settled, it is likely that I2-L38 was brought to Italy by Celtic migrations many centuries after the arrival of Italic tribes from the Alpine Danube region. I2-L38 people would therefore have been autochthonous to the region between the Alps, Central Germany and the Low Countries and were assimilated into the Celtic society during the Hallstatt or La Tène period.
Haplogroup I2b
I2b (L416, L417, L418) is a very minor subclade so far observed in a few samples from Italy, Germany, Scotland and Iran.
Haplogroup I2c
I2c (L596, L597) probably originated around the Rhine region during the Mesolithic period. I2c* can be divided in four groups: A, AB, B and C.
Group A is geographically limited to Switzerland, Germany, the Netherlands, Sweden, Poland, Britain and Ireland.
Group AB has been found in north-west Iran, around the Caucasus (Armenia and Georgia), in Turkey and in France.
Group B is found at low frequencies in West Asia (Turkey, Georgia, North Ossetia, Armenia, Azerbaijian and north-west Iran), in Southeast Europe (Moldova, Romania, Bulgaria, Albania, Crete), in Balto-Slavic countries (Russia, Ukraine, Belarus, Lithuania, Poland, Slovakia, Czech Republic), as well as in Germany, Austria, Italy, Spain and Britain.
Group C has a similar distribution to group A but has also been found in France, Italy and Norway.
Groups A and C seem to have expanded respectively during the Celtic Bronze and Iron ages, alongside R1b-S116/P312.
Additionally, the subclade I2c1 (L1251) has recently been identified. It is found mostly in Germany and England and in their periphery (Ireland, Norway, France, Italy, Poland). This subclade is thought to be approximately 6000 years old, which places it in the Late Neolithic period. It may be associated with hunter-gatherers from Germany who adopted agriculture after coming into contact with Near-Eastern farmers from the Linear Pottery (LBK) culture.
