Cres Island's Facinating Genetic History

One of the most genetically interesting places in Europe is Cres Island, off the coast of Croatia. They are profoundly different genetically from their neighbors in Croatia or anywhere else in Europe, despite living in a place that has been near a major path of European trade and commerce since before agriculture was invented.

In my view, these are not like European genetic outlier populations such as the Finns and the Basque, and African Pygmies and Khoisan people of Africa, who may be relict populations of their respective continents that survived later waves of farmer expansion (including Indo-European expansion in Europe and Bantu expansion in Africa). Instead, they have more in common with Jewish and Romani populations in Europe, and the people of Madgascar in Africa, as recent recolonizers from the East who have remained genetically distinct.

Another study have found significant examples of halotype F, usually associated with Southeast and East Asia, on a Croatian island, but that population was otherwise typical of the European norm. There are a variety of possiblities, only some of which were addressed in the paper that could explain this discovery. The paper fails, for example, to note how common sea trade with Asia was in this area in the 15th century. Cres Island, however, is different. The population is too distinct from the European norm to be easily explained with founder effects in local populations, or isolated instances of admixture. The genetic evidence from Cres Island points to a wholesale population replacement.

High Caste Indo-Aryan Speakers From South India, or relict Central Europeans?

The abstract of a new academic paper on their Mitochondrial DNA heritage is reprinted at Dienekes' Anthropology blog, and in five comments to that post, I spin out a plausible, but unproven story, to explain how this group of people, who show a strong genetic linkage to the Indo-European language speaking Havid Brahmins of South India, could have wound up on a Balkan Island.

I also briefly discuss reasons why it is less plausible, given the genetic evidence, that they have direct roots in Europe's early Neolithic Central European Linear Pottery Culture. The South Asian N1a halotype common on Cres Island is not the same as the version found in Central Europe. It is the smoking gun as it is found only among the Havid Brahmins of South India.

The U2e halotype is not the U halotype associated with early Neolithic Europeans like the Basque, although it is found in both Europe and India, and in particular among with upper caste Indo-European language speaking people from India. Central Europeans have a high frequency of halotype J (associated with the Near East), but only one person out of 119 mtDNA types on Cres Island had that halotype. And, halogroup W is not inconsistent with a high caste Indo-European speaking South Asian source for this population. Halotype U2, which is common in this population, is also found in Mongolia, but for a variety of other reasons, the genetic makeup of this population bears little similarity to the genetic makeup of the people of Cres Island, Croatia.

The history of the Havid Brahmins in South India, which had a thirty-two man population bottleneck around 300 AD, also provides a reason for there to be only a small number of lineages (probably just five lineages account for more than half of the Cres Island population). There is also a plausible, although dim link between Cres Island mythology and the mythology of the Havid Brahmins.

Finally, there is some genetic evidence (I read it recently and don't have a cite) that colonizing populations typically remain distinct from the locals for about a thousand years. If, as I suggest, the Cres Island people arrived at Cres Island in the 800s, this seems plausible. If, instead, they are a relict population from the earliest European Central European farmers, however, the Cres Islanders would have to have remained endogamous for five thousand to seven thousand years, which is less plausible.

Any genetic links between Cres Islanders and the Central European are probably remote. Early Central European farmers (who came out of Anatolia), probably speaking a proto-Indo-European language, are probably closely related genetically to nomadic pastrolists (i.e. herders) in Southern Russia North of the Caucus Mountains. These herders, in turn, were probably the source population for the Indo-Aryan a.k.a. Vedic civilization that conquered North India's earlier Dravidian language speaking people (possibly descended from pre-Semetic Mesopotamians via the Harappan Indus River Valley Civilization), and imposed themselves and their language and religion on the farming people they conquered as a ruling caste. They probably won, in significant part, because they had horses and knew how to use them in war. At this point, the Hindu religion came into being from synthesis with local religious ideas, and the various languages descended from Sanskrit, which is close to being a proto-Indo-Aryan language emerged. The Havid caste in South India claims, plausibly in light of their well studied genetic makeup, religious practices, language, and some sparse ancient written inscriptions, to have come from an area in North India in the foothills of the Himalayan mountains. There is also evidence that the caste system in India has maintained genetic isolation of groups living near each other must longer than any other place in the world.

Thus, the Havids of South India probably are remote descendants of early Central European farmers, but are sufficient remote that they can be distinguished pretty definitively through population genetics.

How Did They Get There? The Story I Propose.

Suppose that the Cres Islanders come from South India. How did they get from South India to Croatia?

I propose that they migrated to a city near modern day Baghdad when it was ruled by a curious and tolerant king at a time when it was the largest city in the world via the India Ocean along trade routes which we know from historical evidence existed at the time in the early 400s. Indeed, there is historical evidence that representatives of the early Christian church in South India (associated with Saint Thomas) attended the Council of Nicea in 325 AD.

I propose that this tight knit community then migrated to Antaolia in the Eastern Roman Empire, with whom they would have had contacts from a church conference held near the city in 410 AD, up the Tigris River, when a contemporary adversary of Attilla the Hun who ruled the empire based in this city two kings later, went on a harsh campaign to suppress minority religions.

Not long after that, the Byzantine Empire split from the Western Roman Empire. A couple of hundred years after that, there were hundreds of years of war between the rising Islamic Empire and the Orthodox Christian Byzantine Empire.

In the early 800s, Cres Island was sacked by Islamic forces, but the invaders weren't able to hold the territory for long. This happened at the peak of their first expansion into Europe a little beyond the furthest extent that they controlled on a sustained basis in Italy, Spain and the Balkans. At around the same time, the Byzantine army has a policy of forcibly seizing religious minority communities (often from Muslim controlled areas) and resettling them as farmers in areas that they controlled.

Somewhere along the way between the 400s and the 800s, this community probably adopted its own distinct version of Orthodox Christianity. The may have been South Asian Christians who came to the Near East for this reason, or they may have converted once they arrived. We know that the Romani people made as similar conversion to Christianity in their recolonization of Europe from India.

I propose that the descendants of the Havid people from India, still functioning as a tight knit community of agriculturalists, were brought in to repopulate Cres Island and came to become the predominant local population. This wouldn't have taken much. The island has an are of only about 160 square miles and a current population of 3,238 with all the benefits of modern technology. One expects that the island was more sparsely populated in the 800s when agriculture was less efficient, particularly in the wake of having its biggest city burned and raided during the Byzantine-Arab war when large scale taking of prisoners was common (more than 16,000 prisoners were taken by the Arabs over a few years at one point in the war).

The Cres Islanders then came under the rule of the Republic of Venice, from 1000 to 1358, then under the Croatian-Hungarian kings, and then from 1409 to 1797 until the 18th century.

The Venetians Republic was built on the trade of its merchant princes, rather than its military superiority, so they may have left the new Cres Islanders more or less alone in a way that other principalities of the Middle Age would not (perhaps explaining why similar communities aren't found elsehwere in Europe). Equally important, Venice was from the start at its founding in 421 AD, a Western Christian city, not an Orthodox Christian one.

The Cres Islanders may have been culturally divided and hence able to remain endogamous as an Orthodox Christian minority outpost in Western Christian Republic. Osor, a town on the island, served as an archdiocese of the Orthodox Christian church from the 500s, and in my theory, was resettled with the Cres Islanders by an Orthodox Christian Byzantine empire.

Osor led a Roman Catholic diocese until 1838. The Roman Catholic Pope (Innocent IV) gave churches in the area permission to use the Old Croatian language, unlike the rest of the Roman Catholic Church, in 1248, so the transition from being under the authority of the Eastern Church to the Western Church probably took place around then. The fact that Cres Island conducted its religious services in Old Croatian rather than Latin, like the rest of the Roman Catholic Church, probably helped it maintain its cultural isolation that led to its genetic isolation, even after it joined the Western church.

The power of religious and cultural differences to maintain the endogamy needed to sustain a distinct genetic identity is well attested in the same time period by the Jews, who would have co-existed in the Near East and in many less geographically isolated villages in Central Europe in the same time period, there were also largely endogamous Jewish ghettos in Venice at the same time that Cres Island was ruled from Venice.

The fact that the Cres Islanders are now Christians also has precedent in the experiences of the Romani people and a large share of Iberia's Jews during the reconquest.

Is this a true story?

This is historical fiction. It is a story that is consistent with the historical facts that we know that could have happened. It is a plausible theory that can explain a highly improbable fact, that the people of an island off the coast of Croatia appear to be descended genetically from a specific group of people in South India, in a way that involves a sensible chain of cause and effect.

Other ways that this could have happened seem less plausible. Archeological evidence and even reference to the island in the Illiad, make it clear that Cres Island was inhabited long before the Havid people of South India existed.

The sack of Osro in 841 is the most notable historical event since the Havid people came to exist that could have depopulated the island sufficiently to allow its population to be replaced almost entirely by migrants descendant from South India. The pronounced genetic distinctness of the Cres Island people despite robust contact with the outside world for thousands of years supports their relatively recent origins. Mechanisms for them to remain distinct in that time period since 841 exist.

There were precedents for this kind of mass relocation of members of minority religious sects at the time, as in the case of the Maronite Church (an Eastern rite church affiliated with the Western Church's Pope):

Following the death of Maron in 410, his disciples built a monastery in his memory and formed the nucleus of the Maronite Church.

The Maronites held fast to the beliefs of the Council of Chalcedon in 451. When 350 monks were slain by the Monophysites of Antioch, the Maronites sought refuge in the mountains of Lebanon. Correspondence concerning the event brought papal and orthodox recognition of the Maronites which was solidified by Pope Hormisdas (514-523) on February 10, 518. A monastery was built around the the shrine of St. Maro after the Council of Chalcedon. . .

In 687 the Emperor Justinian II agreed to evacuate many thousands of Maronites from Lebanon and settle them elsewhere. The chaos and utter depression which followed led the Maronites to elect their first Patriarch, John Maroun, in 687. This however was seen as a usurpation by the Orthodox churches. Thus, at a time when Islam was rising on the borders of the Byzantine Empire and a united front was necessary to keep out the Islamic infiltration, the Maronites were focused on a struggle to retain their independence against imperial power. This situation was mirrored in other Christian communities in the Byzantine Empire and helped facilitate the Muslim conquest of the most of Eastern Christendom by the end of the century.

The Maronites may have also provided a precedent for the papal relationship with the Old Croatian churches forged in the 13th century.

It isn't unprecedented for people to travel thousands of miles to colonize an island with a people completely different in ancestry for other people who live nearby. Madagascar tells that story. We also see something similar in Indonesia. An the Andaman islands illustrate the point that two places near each other can be very genetically distinct. We know that something close to that happened in Greenland, although it didn't last, but it came close. The Maronites live in large numbers in Latin America today.

It is hard to imagine any reason that the Croatian King (who ruled for only about 50 years) would have replaced the people of Cres Island would have had a people of South Asian origins (who are not Romani) to place on the island or that he could have done so without attracting prominent historical notice. The Venetians probably did have trade with South India (Marco Polo hailed from a small Italian city state), but there is no reason to think that they would have replaced the local population so completely.

One could image an earlier date for the migration of the ancestors of the Cres Islanders, perhaps in the 500s when the Orthodox archdiocese was established. But, much before that the Havid people wouldn't have been around to migrate to the island, and mass slaughter and prisoner taking seems like a more likely reason to move in to a new island.

One could imagine a different scenario. Maybe the Cres Islander's ancestors were a culturally distinct population that co-existed was indigeneous Cres Islanders for an extended time period. But, perhaps the food supply declined in the Little Ice Age in the Middle Ages, but superior agricultural talents of a people who are known as accomplished agriculturalists in South India, and a strong sense of community, allowed them to survive, while their neighbors gave up and left for Venice, died of starvation, died of disease while weakened by starvation, or died from a disease that the Cres islander's ancestors were immune to or not exposed to on account of different culturally vestigal practices surviving from their Hindu religious concerns about purity. Their island's signature lake myth about a woman who refused to share food with her sister could be evidence of the power of that kind of historical event to shape an earlier ill remembered myth from their ancestors.

The possibility of selection by disease is not merely hypothetical in this case. There is genetic evidence that a 15th century plague had a powerful selective effect in the area that strongly favored people with genes adapted to this disease.

Aim

To assess the frequency of 32 base pair deletion in CCR5 (CCR5Δ32), which has been shown to confer resistance to HIV infection in a homozygous form, in 10 isolated island communities of Dalmatia, Croatia, with different histories of exposure to epidemics during and since the medieval period.

Methods

In 2002, DNA analysis of 100 randomly selected individuals from each of the 10 isolated communities of 5 Croatian islands (Susak, Rab, Vis, Lastovo, and Mljet) showed high levels of 3-generational endogamy, indicating limited gene flow. Five of the communities were decimated by epidemics of unknown cause between 1449-1456, while the other 5 villages remained unaffected. . . .

Results

The frequency of CCR5Δ32 in the 5 villages affected by the epidemic was 6.1-10.0%, and 1.0-3.8% in the 5 unaffected villages. The Δ32 mutation was found in 71 of 916 alleles among the individuals from the affected villages (7.5%), and in 24 of 968 alleles in unaffected villages (2.5%, χ2 = 27.3, P < 10−6). A previous study in 303 random Croatian blood donors showed the frequency of the CCR5 Δ32 of 7.1% in the general population. . . .

Conclusion

Our results and historical evidence, suggest that the mid-15th century epidemic could have acted as a selection pressure for the CCR5Δ32 mutation.

A 17th century plague in an isolated community in Southern Italy known from historical evidence has similarly been shown to have left a clear genetic impact on the surviving population. (The plague is believed to have originated in Central Asia, although the bubonic plague theory for what that disease was now has competition with other candidate diseases.)

I considered that possibility that the Cres Islanders made their way to the island via Attila the Hun, but that seems less likely, given the extent of his conquest, than a Byzantine way point.

The path from South India to the Byztantine empire is particularly fuzzy. They could have come directly, bypassing the empire in between. The Roman empire certainly could have been a draw, perhaps under the reign of Constantine I or in the wake of news from the Council of Nicea.

But, if they had done that, why wouldn't they have ended up in Rome, and why wouldn't they have gone to an island that was part of the Western Roman Empire from the start?

The path that I propose is better motivated, and once they arrive in the Near East follows a path of least resistance. The reason for their group to travel to the Near East is also reasonably well motivated.

My story doesn't have much corroborating evidence from Cres Island itself, just one myth vaguely similar to one from India. DNA evidence is powerful, but I'd like to have more than that and a history book or two to rely upon. The story I've told provides enough probable cause to make it worthwhile to dig deeper and look for those connections in a place nobody know to the wider world ever had any reason to expect or look for connections before the DNA evidence was available.

Perhaps there is some plant grown on Cres Island that is native to South India and found nowhere else in Europe.

Perhaps it would be possible to take DNA samples from continuous used cemetaries to see how far back the current genetic makeup of Cres Island existed. Similar studies are being done now with the Eustrician/Tuscan divide.

Perhaps there are words of South Asian origin found only in Old Croatian out of all of the languages of Europe. Then again, it isn't at all unprecedented for genetically distinct populations, like African Pygmies, to adopt the languages of neighboring people and lose their own languages entirely.

Perhaps that are cultural practices unique to Cres Island that survive, or artifacts from the Middle Ages that show some sort of linkage.

Perhaps someone familiar with Roman, Byzantine, Venetian or Mesopotamian historical records might recognize a passing reference to these people if they knew what to expect. Perhaps other less widely known local myths would provide further connections.

If anyone is willing to pay me a living wages and expenses to do more research, I just might.