The Story of Haplogroup I

Haplogroup I is the only Y-Chromosome haplogroup that is autochthonous to Europe. This means that is emerged (evolved) and is "native" to Europe, and also that is found almost nowhere else. The I Haplogroup emerged probably somewhere in Central Europe, after their ancestors, the second wave of Homo Sapiens Sapiens, colonized Europe. Haplogroup I is marked by the M170 marker, which all men carrying M26 also bear.

The Branches of Haplogroup I

Haplogroup I has diverged into several branches, or subclades. The three major branches are distributed primarily in Scandinavia (M253), the Balkans (P37.2 or L68), and Northern Germany. The distribution of these branches is clinal, meaning essentially, that it is possible to tell on a map clearly where the haplogroups likely originated, where they are most concentrated, and where they spread. Think of mapping a spill.


The distribution of subclade M26 is not clinal. There is no clear region where M26 emerged, and no clear map of its spread. Men bearing M26 are spread along the western seaboards of the Mediterranean and Atlantic. M26 has the most western distribution of any haplogroup.

Ethnic Groups Bearing M26

M26 is found among males of the following far-flung locales (in order of prevalence): Sardinia, Castile, coastal Spain, Pantellaria Island, Basque Country, Canary Islands, Sicily, Channel Islands, France, Ireland, coastal England, Holland, Italy, Wales, Corsica, southern Sweden, Belgium, Orkney Island.

Earliest Archaeological Sites in Western Europe Attributed to Haplogroup I

According to most theories, Haplogroup I is associated with Gravettian culture. The western Gravettians were responsible for the cave paintings at Lascaux, and other sites in France. If you are descended from I-M26, the westernmost marker and the only one still found in France and Spain, you are likely descended from humanity's first artists!

Studies and Graphics

Are posted frequently. Check back often!
Rare Marker on Y-Chromosome Tracks the Distribution of
European Megaliths

Abstract: Most archaeologists agree that the Megalithic (or large stone building) cultures of the Western Mediterranean and Atlantic Seaboard of Europe shared a multitude of common features. Nevertheless, whether these cultural features were transmitted through limited, non-genetic exchanges or spread by a more-or-less homogenous “mother” culture has been the topic of considerable debate. The author proposes a correlation between the Megalithic material culture and a Y-Chromosome sub-haplogroup (I-M26), whose unique pattern of distribution suggests a sea-based spread. I-M26 is found almost exclusively in locales that, during the late Mesolithic and early Chalcolithic, featured significant megalithic building activity. As such, I-M26 unites populations with little in common (e.g., Sardinia and the Orkney Islands) other than their significant megaliths (e.g., the Nuraghi and Skara Brae) suggesting a late Mesolithic dispersal of an elite builder population responsible for the spread of Megalithic culture and building.


For years, geneticists, archaeologists and the curious have speculated on who built the megaliths, the large stone structures like Stonehenge that dot the Western European landscape from Spain to Sweden. Scientists have long debated whether a group of conquering colonists sharing a common origin built the megaliths or whether the knowledge, skill and impetus to build the megaliths were transmitted culturally only. A genetic link has been discovered between a tiny percentage of men who inhabit the regions in Europe where a megalith is located. This genetic marker dates back to the Stone Age, and lends significant credence to the former theory.
Megaliths (or prehistoric, large stone structures used for defensive, territorial, burial, religious or astronomical purposes) are located over a broad expanse of Western Europe in countries touching the Atlantic seaboard, the Western Mediterranean and the North Sea (Cavalli-Sforza 1995). Because of the apparent similarities between faraway megaliths and the obvious need for significant technological advances to have occurred for ancient peoples to engage in building projects of such magnitude, archaeologists (beginning with antiquarian Jacques Cambry’s theory of a “Celtic” connection in 1805) have speculated that one culture was responsible for the spread of megalithic building.

Nevertheless, it has been debated whether even the most materially similar megaliths were created by a unitary, homogenous society of builder-colonists or simply a network of mutually influential, heterogeneous societies. Even archaeologists and geneticists favoring the former theory have speculated whether the megaliths were created by a single culture that settled the megalithic locales in large numbers or alternatively, whether the expertise necessary to erect megaliths along with the impulsion (whether religious, political or astronomical) was spread by a small, roving aristocratic or priestly group of elites, who imposed these large-scale building projects on the groups they encountered.

In modern times, searches for genetic links among the inhabitants of megalithic lands using nuclear and autosomal DNA have thus far been fruitless, discrediting the notion that, presuming a homogenous megalithic group existed, it settled the various megalithic locales in large numbers (Cavalli-Sforza 1995).

In the last decade, research into gonosomal DNA (i.e., genes passed unrecombined through either parent) has shown great promise for tracking prehistoric migration patterns. Studies of the non-recombinant portions of the Y-Chromosome have uncovered, inter alia, phylogeographic evidence linking different haplogroups to the spread of early farmers from the Levant during the Neolithic (Semino, et al. 1996); the spread of Uralic speakers in the extremes of Northeast Europe (Passarino, et al. 2002); and the post-Last Glacial Maximum (LGM) diffusion of major European lineages from Iberian, Balkan and Eastern European refugia (Semino, et al. 1996; Rootsi, et al. 2004). Other researchers have argued convincingly that the spread of certain prehistoric material cultures, most notably the painted pottery and ceramic figurines found across the Mediterranean can be linked with one or more Y-Chromosome haplogroups (King & Underhill 2002).

This paper proposes that a rare sub-haplogroup on the Y-Chromosome distinguished by the M26 marker, tracks the distribution of megaliths throughout Western Europe.

Y-Chromosome Sub-Haplogroup I-M26

M26 is the distinguishing Single Nucleotide Polymorphism (SNP) of the Y-Chromosome sub-haplogroup now known as I1b1b. (International Society of Genetic Genealogy, 2006). The Y-Chromosome Consortium previously referred to M26 as I1b2, a name that appears in many older scholarly publications. (Y-Chromosome Consortium, 2002). To avoid confusion, throughout this paper the sub-haplogroup is referred to by its distinguishing SNP (i.e., M26).
M26 is unique among sub-haplogroups of Hg I/M170, in that unlike most others (whose concentration peaks in Scandinavia or the Balkans) M26 has a uniquely Western European domain (Table 1). (The one other exception is I-M223, but I-M223 has a definite center of distribution in Northeast Germany). Assuming the initial distribution of the M170 mutation centered in the Balkans, was associated with Gravettian culture and that M26 bearers weathered the LGM in an Iberian refugium (Rootsi, et al. 2004), the likely site of the initial M26 expansion was in and around modern Dordogne, France, close enough to a putative Cantabrian refugium and the locus of significant Gravettian finds.

M26 bearing males are found in extremely low percentages in a select group of countries in Western Europe. Unlike the distribution of most other haplogroups in Europe, the distribution of M26 is not clinal. It is located, for the most part, in the regions of Western Europe bordering the seas. More so than any other haplogroup, it is distinguished by its notable numbers found on islands. Lands featuring some of the highest concentrations of M26 include Sardinia, Pantellaria and the Canary and Channel Islands, but it also is found in significant percentages on Corsica, Eastern Sicily and Orkney Island (Table 1).

So far, no theory has been postulated to explain adequately the curious distribution of M26. Aside from the fact it is a rare clade, the lack of such theories is likely to due to the fact that while some have tested for M26 in a specific region, and others have conducted broad surveys of European groups as a whole, no one has studied M26 on a micro-regional level for all localities throughout all of Europe.


For present purposes, all studies on Y-Chromosome SNPs that tested for M26 were aggregated (Semino et al. 1996; Rootsi et al. 2004; Scozzari, et al. 2001; Flores, et al. 2004; Capelli, et al. 2003; Flores, et al. 2003). Special caution was employed not to factor in the work of researchers who similarly aggregated other samples. These samples were added together and averages recalculated producing more accurate percentages, which is important considering the topic of the study is a clade where one occurrence in 100 is significant.

To augment these data, searches were performed using modal haplotypes in the Y-Chromosome Haplotype Reference Database (YHRD), along with the two largest other publicly available databases (SMGF, Ysearch). With the latter two, for individuals who had not undergone SNP testing, YCIIa/b = 11, 21 and DYS 385a/b = 12, 12 were used as primary Short Tandem Repeat (STR) polymorphism indicators of M26. Only data coming from men with clearly documented, reliable information on the Old World town of origin of a direct male ancestor born before 1900 were considered. For YHRD, which does not yet provide for searches on YCII, searches were conducted using the following the M26 modal haplotypes (Bosch, et al. 2001), variations of which are as follows: {A} DYS 385a/b = 12,12; DYS 389i/ii = 13,28; {B} DYS 385a/b = 12,12; DYS 389i/ii = 14,30; {C} DYS 385a/b = 12,12; DYS 389i/ii = 14,29; DYS 392 = 11; DYS 393 = 13; {D} DYS 385a/b = 12,13; DYS 389i/ii = 13,28; DYS 392 = 11; DYS 393 = 13; {E} DYS 385a/b = 12,14; DYS 389a/b = 13,28; DYS 392 = 11; DYS 393 = 13. To avoid false positives, care was taken to run each individual’s haplotype through haplogroup predictor software. (Athey, 2005). This unprecedented amount of data on the localities where M26 is found allows for a phylogeographic study of the clade.

Plotted on a map, it is readily apparent that contrary to other well-understood European haplogroups (such as R1a or N3), M26 was spread initially via the seas (Figure 1). This implies a time frame for the spread during an era of fairly advanced seafaring.

{Graphic omitted}

Historical mechanisms for the spread were carefully considered, then eliminated. For example, the significant presence of M26 in Britain, Calabria, Normandy, other parts of France and Sweden have caused speculation that the marker tracks at least in part the Norman conquests toward the end of the first millennium C.E. Nevertheless, the high presence in Sardinia and Iberia, the relatively low presence in Scandinavia, and the time to most recent common ancestor (TMRCA) calculations (performed by SMGF) tend to discredit the Normans as the mechanism for M26 spread. For similar reasons, the Vandals and Visigoths as mechanisms were considered and then rejected.

I-M26’s Overlay with the Distribution of Megaliths

Prehistoric movements of people were then reviewed. The distribution of M26 bears an extraordinary similarity to the distribution of megalithic structures in Western Europe (Figure 2). This extraordinary similarity to the map showing the distribution of megaliths indicates, by the simplest interpretation, that there was a migration of a population of males, associated with megalithic building, who had a small but significant impact on the Y-chromosomal diversity of the diverse lands they visited.

{Graphic omitted}

Aside from the fact that both M26 and megalithic building activity appear to be the only markers uniting the vastly different locales (e.g., the Canary Islands, South Sweden, Andalusia, Sardinia, Belgium, Orkney Island) denoted in Tables 1 and 2, several other factors support the notion that M26 tracks the movement of a megalith-building culture. Primarily, the simple facts that the highest concentrations of M26 are found in locales that had the most energetic, prolific megalithic building activity (e.g., Sardinia, parts of Iberia and specific locales in the United Kingdom) and the unexpected absence of M26 is regions where, coincidentally, megaliths are also absent (e.g., both megaliths and M26 are found in Sweden, but not Norway; Northeast Germany but not Southeast Germany, etc.) also weigh heavily in favor of the hypothesis. Moreover, the presence of M26 in parts of Germany that were the centers of significant Bronze Age commerce and astronomy (Meller, 2004) buttresses the notion of a spread in both the time frame and mechanism as described above. Finally, it would appear STR diversity of M26 males based on TMRCA calculations matches a separation time coinciding with the approximate time the megaliths were built.

Several other, non-genetic factors support the notion of significant contact between Western European maritime locales along the Atlantic zone during the Neolithic. For example, research into Ireland’s pygmy shrew (a small mammal half the size of a mouse) reveals it originated relatively recently in the Pyrenees, and was brought to the island on boats by humans during the late Mesolithic or Neolithic period. (Mascheretti, et. al. 2003). Similarities in Neolithic artistic styles in Iberia and the British Isles have been extensively described (Bradley & Valcarce 1998). Others have pieced together the various clues to argue for a more-or-less unified prehistoric European Atlantic culture, extending as far north as Scandinavia and south into the Western Mediterranean (Cunliffe 2004). Nevertheless, no study thus far has proposed M26 as genetic proof of such exchanges. (Indeed, no study has posited a Y-Chromosomal link for the “Megalithics” at all, despite the likelihood that a movement of elite or semi-elite sailors along the coasts during the Neolithic would likely leave some genetic vestiges along the male inherited Y-Chromosome).


It is likely that small groups of megalithic mariners influenced greatly the religious, political, cultural (and physical) landscape of the lands to which they ventured during the Neolithic. M26 is a strong candidate for the marker of a “single population of colonizers, navigators and cultivators” (Cavalli-Sforza 1995) which likely originated somewhere in the vicinity of the Pyrenees shortly after the LGM. As Cavalli-Sforza noted, “the Megalithics may have even been a priesthood or some kind of prehistorical aristocracy, who had good ships and perhaps good weaponry, as well as a much more advanced understanding of astronomy and architecture than their contemporaries.” Somewhat counter-intuitively, the low concentrations of M26 everywhere where it is found is consistent with a spread by a small population of seafaring elites during prehistoric times.

Further research is clearly necessary to answer several unresolved questions. Certain important megalith regions have thus far escaped in-depth Y-Chromosomal analysis (e.g., France and Malta). (It is important to note that M26 may not be present in large numbers in Malta, however, due to the fact that it has been almost entirely depopulated and resettled during historical times. For purposes of this theory, Pantellaria served as an appropriate proxy). Additional research is necessary to confirm the likely significant percentages of M26 in specific British locales, where for purposes of the present study, given the inherent limitations in the databases, precise percentages were impossible to calculate. (Table 2). Moreover, additional research on STR diversity would presumably help identify which precise region is the most likely candidate for the original homeland of the megalithic culture.
In the meantime, the considerable overlap between the maps in Figures 1 and 2 is too significant to be ignored.

Acknowledgments. I wish to thank Peter Underhill and L. Luca Cavalli-Sforza for their encouragement and helpful comments.

Athey, W. Y-Haplogroup Predictor. Available at (last updated 26 June 2005).

Bosch, E., F. Calafell, D. Comas, P.J. Oefner, P.A. Underhill & J. Bertranpetit. 2001. High-resolution Analysis of Human Y-chromosome Variation Shows a Sharp Discontinuity and Limited Gene Flow Between Northwestern Africa and the Iberian Peninsula, American Journal of Human Genetics 68: 1019-29.

Bradley, R. & R.F. Valcarce. 1998. Crossing the Border: Contrasting Styles of Rock Art in the Prehistory of North-west Iberia, Oxford Journal of Archaeology 17: 287-308.

Capelli, C., N. Redhead, J. Abernethy, F. Gratrix, J. Wilson, T. Moen, T. Hervig, M. Richards, M. Stumpf, P. Underhill, P. Bradshaw, A. Shaha, M. Thomas, N. Bradman & D. Goldstein. 2003. A Y Chromosome Census of the British Isles, Current Biology 13: 979-84.

Cavalli-Sforza, L.L. & F. Cavalli-Sforza. 1995. The Great Human Diasporas: The History of Diversity and Evolution. Reading, MA: Addison-Wesley.

Cunliffe, B. 2004. Facing the Ocean: The Atlantic and Its Peoples 8000 B.C. - A.D. 1500. Oxford University Press.

Flores, C., N. Maca-Meyer, A.M. Gonzalez, P.J. Oefner, P. Shen, J.A. Perez, A. Rojas, J.M. Larruga & P.A. Underhill. 2004. Reduced Genetic Structure of the Iberian Peninsula Revealed by Y-Chromosome Analysis: Implications for Population Demography. European Journal of Human Genetics 12: 855-63.

Flores, C., N. Maca-Meyer, J.A. Perez, A.M. Gonzalez, J.M. Larruga & V.M. Cabrera. 2003. A Predominant European Ancestry of Paternal Lineages from Canary Islanders, Annals of Human Genetics 67: 138-52.

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King, R & P. Underhill. 2002. Congruent Distribution of Neolithic Painted Pottery and Ceramic Figurines with Y-chromosome Lineages, Antiquity 76: 707-14.

Mascheretti, S., M.B. Rogatcheva, I. Gunduz, K. Fredga & J.B. Searle. 2003. How Did Pygmy Shrews Colonize Ireland? Clues From a Phylogenetic Analysis of Mitochondrial Cytochrome b Sequences, Proceedings in Biological Science 270: 1593-99.

Meller, H., Star Search: Recovered from Smugglers in a Daring Police Sting, a 3,600-year-old Disk Reveals that Bronze Age Europeans Were Surprisingly Acute Students of the Night Sky, National Geographic January 2004: 77-87.

Passarino, G., G. Cavalleri, A. Lin, L.L. Cavalli-Sforza, A. Borreson-Dale & P.A. Underhill. 2002. Different Genetic Components in the Norwegian Population Revealed by the Analysis of mtDNA and Y Chromosome Polymorphisms, European Journal of Human Genetics 10: 512-29.

Rootsi, S., C. Magri, G. Benuzzi, A. Lin, N. Al-Zahery, V. Battaglia, L. Maccioni, C. Triantaphyllidis, P. Shen, P. Oefner, L. Zhivotovsky, R. King, A. Torroni, L. L. Cavalli-Sforza, P.A. Underhill & A.S. Santachiara-Benerecetti. 2004. Phylogeography of Y-Chromosome Haplogroup I Reveals Distinct Domains of Prehistoric Gene Flow in Europe, American Journal of Human Genetics 75: 1023-34 (2004).

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Table 1

Percentages of I-M26 Males

in Regions Where It Is Found

M26 %
Italy Sardiniaa,b,c
Spain Castiled
Spain Cacerese
Spain Asturiasc,e
Italy Pantelleria Islande
Spain Pyrenees (non Basque)e
Basque country Spain & Francea,d,e,f
Spain Canary Islandsg
Italy Sicily Easterne
England Channel Islandsf
France (Undistinguished)c
Spain Andalusiaa,b,c,d
Spain Barcelonae
Ireland Rushf
England Midhurstf
Spain Zaragozae
France Low (SW) Normandya
Spain Extremadura (+Andalusians)e
Ireland Castlereaf
Netherlands Limburge
England Chippenhamf
Italy Umbriae
Spain Galiciae
Wales Haverfordwestf
Spain Leond
France Corsicac
France Interior Cities (Lyon + Poitier)a,e
Spain Madride
Italy Calabriaa,c
Spain Cantabriad,e
Spain Valenciad,e
Italy Latiumc,e
Italy Centrala
Switzerland Lausannee
Sweden Southa,e
Scotland Orkney Islandf
Germany Hamburge
Germany Badene
Italy Lombardye
Italy Marchee
Italy Tuscanye
Germany Berline
Germany Saxonye

a Rootsi, et. al. 2004 (4)
b Semino, et. al. 2000 (2)
c R. Scozzari, et. al. 2001 (8)
d Flores, et. al. 2004 (9)
e Tested for the present study by conducting a census of M26 modal haplotypes in the Y-Chromosome Haplotype Reference Database (13)
f Capelli, et. al. 2003 (10)
g Flores, et. al. 2003 (11)

Table 2

Regions Where I-M26 Has Been Attested

Belgium Hainut
England Dorchester
England Hampshire
England Lancashire
England Lincolnshire
England Liverpool
England Suffolk
England Surrey
France Alsace
France Normandy
Germany Baden
Ireland Clogher Tyrone
Ireland Cork
Ireland Kerry
Italy Latium
Italy Ragusa Sicily
Scotland Fifeshire
Spain Granada
Wales Glamorgan

Percentages are unknown, due to lack of data on sample sizes. M26 presence verified by a search of online databases used primarily for genealogical purposes. Those databases were: (run by Family Tree DNA, Inc.) and (The Sorenson Molecular Genealogy Foundation). Data was not considered unless the donor had clearly documented information on the Old World town of origin of a direct male ancestor born before 1900, and that the information appeared non-apocryphal. Since these data come from databases serving, for the most part, an educated American population, presumably a large percentage of the donor’s ancestors come from the United Kingdom. This makes up for the fact the UK, as a whole, is not as well studied as certain isolate populations (e.g., Sardinians, Basques, data for which is over-represented in the studies aggregated in Table 1). It is interesting to note that Clogher means “stone” in Gaelic, and that for years people speculated why the town bore that name, until archaeologists uncovered a building that had already become rubble by the fifth century C.E. See