I was reading this Wikipedia article about the genetic history of Italy, and I found it interesting.

There are however a few things that puzzle me, because they seem to contradict each other. For example it states that because of the Alps forming a natural barrier Italy is, along with Finland, a genetic island in Europe. Does this mean Italians and Finns are genetically separated from all other Europeans, and to what extent? Later in the same article it says that "In Italy as elsewhere in Europe the most common haplogroup is haplogroup H", which would seem to contradict the genetic island theory. After all, Italy has been colonized by countless populations throughout its history, which might suggest the Alps didn't really stop the gene flow from neighboring countries (not to mention that other European countries are equally separated by mountains, like Spain).

I have no background in genetics whatsoever, so excuse my ignorance, I'm just trying to understand an article that seems very confusing and throws lots of different information together.

EDIT: Thanks for the quick reply! I've found another link (which seems to be more reliable than Wikipedia's unverified claim), though it still sounds like a weird theory to me.

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    $\begingroup$ Please don't ask many questions in a single post. Split them up into separate questions instead. I have removed the second question, please post it again separately. $\endgroup$ – terdon Nov 24 '13 at 16:22
  • $\begingroup$ you have to remember that in most human history people just didn't move around like can now. population haplogroups do migrate, but slowly enough to identify their movement. The Alps didn't stop migration, but they would have kept the flow down significantly compared to the overall migration rate in the french areas, connected by rivers and flatter terrain. $\endgroup$ – shigeta Nov 25 '13 at 19:31

I'm afraid that the "genetic island" idea is almost certainly wrong because

  1. The wikipedia page offers no evidence for this claim:

    Following scientific research carried out by Dutch geneticists, Italy has proven to be one of the last two remaining genetic islands across Europe (along with Finland), this due to the presence of the Alpine mountain chain that, over the centuries, has prevented large migration flows aimed at colonizing the Italian lands.[citation needed]

    Remember that any random idiot person can edit a wikipedia page. If there is no supporting reference for a claim you find in wikipedia, you should treat it as suspect.

  2. As you point out, the Alps only block entry on the north of Italy. Italy, however, is a pretty large peninsula, completely open to the sea along its entire length. For example, here is a map of Greek and Phoenician colonies circa 530bc (source):

    enter image description here

    As you can see, significant parts of the coast of what today is Italy were colonized by Greeks and Phoenicians. There were many subsequent waves of migration and/or invasion by various tribes such as

    enter image description here

  3. An article by Brisighelli et al. (which is actually quoted at the very top of the Wikipedia page you linked to) mentions that (emphasis mine):





    Before the Roman conquest, ancient Italy was characterized only by the presence of Indo-European populations living in the Italian Peninsula since the second millennium BC, corresponding to the period between the Iron Age and Romanization. During all this period there were also increasing contacts with the Phoenician and Greek colonists: the former being largely present on the coasts of Sardinia and western Sicily and the latter in Southern Italy.


    At the beginning of the first millennium BC the following native tribes could be distinguished on the Italian territory: the Ligures, on the coast that bears their name, in the northern Apennine valleys, part of the pre-alpine valleys and the western Po Valley; the Sicani, in the interior of Sicily; and the Itali, in present-day Calabria (from whom comes the name ‘Italy’, which was to be extended to all the territory of the peninsula). Besides the already mentioned Terramare tribe, on the southern edge of the Po Valley, and the Villanovans, probably from Eastern Europe who settled throughout Central Italy, there were also the Umbrians to the east of the upper basin of the Tiber. The Veneti, who occupied the territory that still bears their name, originally came from Illyria as did the Messapii (now modern Salento or South Apulia) and Iapyges, who settled in present-day Puglia (Apulia) 5. Many other populations of Central-Southern Italy were created by the mixing of local and foreign elements dating back to the previous millennium; it is the case of the Sabines and Latini who settled in Lazio together with Falisci, Aequi, Volsci, Hernici and Ausones. The interior of Abruzzo was dominated by the Vestini, Paeligni and Marsi, while the central Adriatic coast was populated by Picentes, Marrucini and Frentani. The Apennine area of Molise and Basilicata was peopled by the Samnites and Lucanians. In Calabria and Sicily there were also the Bruttii and Siculi.


    Molecular indices indicated that most of the Italian samples show diversity values that are comparable to other European populations. However, some differences were shown to exist, especially in isolated Ladin populations.


  • Brisighelli F, Álvarez-Iglesias V, Fondevila M, Blanco-Verea A, Carracedo Á, et al. (2012) Uniparental Markers of Contemporary Italian Population Reveals Details on Its Pre-Roman Heritage. PLoS ONE 7(12): e50794. doi:10.1371/journal.pone.0050794
  • $\begingroup$ To your point 2 I would also like to add that the fixation with land routes is a recent phenomenon. In ancient times, travel by sea was much easier than travel by land (roads were often few and poor), which meant that distant places linked by sea or rivers could be much more connected (both travel and gene flow-wise) than areas that were geographically closer together but linked by land. $\endgroup$ – fileunderwater Sep 15 '15 at 9:01

No, Italy is not a Genetic island but Sardinia is;

  1. There is no such thing as a genetic Italy or an Italian (genetically); Italian groups (North Italians / Central Italians / South Italians / Sicilians / Sardinians) are diverse and do not cluster with each other (DiGaetano et al 2012 / Nelis et al 2009) in PCA-plots; In fact Italians are just as little related with each other (IBD sharing) as they are to other nations (Ralph & Coop 2013);

  2. In general North and Central Italians cluster closest to each other and to Greeks and Albanians while South Italians cluster between Greeks and Cypriots (Lazaridis et al 2013);

  3. What is truly a 'genetic island' is the island of Sardinia; The Sardinians are an isolated population and only cluster with old Neolithic-Europeans (Keller et al 2012 / Lazaridis et al 2014 / Gamba et al 2014 / Haak et al 2015), reason being they are ~90% genetically identical (inheritance) with the old Neolithic-Europeans (Haak et al 2015 / Sikora et al 2014);

  4. As for the quoted study i.e. Lao et al 2008; It is not clear (to me) what the sample make-up of IT1 is; In Figure S2 one can clearly see its samples clustering all over the place; Some samples cluster in between Greeks (EL) and Swiss (CH) where as others are completely isolated; I assume that these samples are from all over Italy incl. Sardinia and that the isolated samples are the Sardinian ones; Lao et al is a study from 2008, and probably because of such results, more recent studies tend to label the Italian samples according to region (North Italians / Tuscans / South Italians / Sicilians / Sardinians) in order to have a clearer insight;

So the real 'lesson' is that Italians, despite being politically ONE nation, are in fact however genetically diverse i.e. not one people; And Sardinians are an isolated old-stock, in fact the last Neolithic remnants in Europe;

Ultimate advice: Dont bother with Wikipedia and whatever someone has written there; Read the studies themselves (first hand), thats the most reliable;

Some inside into Italian genetics:

K=7 and K=9 Admixture analysis (incl. North Italians / Sardinians) Di Cristofaro et al 2013 http://s3-eu-west-1.amazonaws.com/previews.figshare.com/1251712/860/p_01.png

K=10 Admixture analysis (incl. Tuscans / Sardinians) Behar et al 2010 http://s14.postimg.org/g7agga7e9/u1u11.png

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    $\begingroup$ That's an interesting answer. Can you add links to the cited papers? $\endgroup$ – Chris Sep 15 '15 at 7:27

Italians do have much less IBD sharing with other European populations and are more easy to distinguish based on aDNA from other European population, so this enforces the model of the ''genetic island''



Data for the map were generated by gene chips programmed to test and analyze 500,000 sites of common variation on the human genome, although only the 300,000 most reliable sites were used for the map. Dr. Kayser's team tested almost 2,500 people and analyzed the data by correlating the genetic variations in all the subjects. The genetic map is based on the two strongest of these sets of correlations.





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