Genetic history of Italy

According to archaeological records and historical documentation, Italy has been a melting pot for populations of different geographical and ethnic matrices. Although Italy has been a favorite subject for numerous population genetic studies, genetic patterns have never been analyzed comprehensively, including uniparental and autosomal markers throughout the country.^[1]

Not all of these various peoples were linguistically or ethnically closely related. Some of them spoke Italic languages, and others belonged to another Indo-European branch (Ligurian, Venetic, Lepontic) or were non-Indo-European (Etruscan, Raetic).

In 2008, Dutch geneticists determined that Italy is one of the last two remaining genetic islands in Europe (the other being Finland.) This is due in part to the presence of the Alpine mountain chain which, over the centuries, has prevented large migration flows aimed at colonizing the Italian lands.^[2]

Historical population of Italy

• Modern man appeared during the Upper Paleolithic. Specimens of Aurignacian age were discovered in the cave of Fumane and dated back about 34,000 years ago. During the Magdalenian period the first men from the Pyrenees populated Sardinia.^[3]

• During the Neolithic farming is introduced by people from the east and the first villages are built, weapons become more sophisticated and the first objects in clay are produced.

• In the late Neolithic era the use of copper spreads and villages are built over piles near lakes. In Sardinia, Sicily and part of "Continental Italy" the Beaker culture spreads from Western Europe.

• During the Late Bronze Age the Urnfield or Villanovan culture appears in Italy, characterized by the typical rite of cremation of the bodies originating from Central Europe, the use of iron spreads.^[4] In Sardinia the Nuragic civilization flourishes.

• From the 8th century BC Greek colonists settle on the southern coast and in Sicily and found cities, initiating what was later called Magna Graecia. The Etruscan civilization developed on the coast of Tuscany and Latium. In the 5th century Celtic tribes from continental Europe settled in Northern Italy and parts of Central Italy.

• With the Fall of the Roman Empire different populations of German origin invaded Italy, the most significant was that of the Lombards, who will try to unify politically the "Boot of Italy".

Y-DNA genetic diversity

The majority of Italians, Sicilians and Corsicans belong to Haplogroup R1b, common in Western and Central Europe. The highest frequency of R1b is found in Garfagnana (~ 80%), Tuscany This percentage lowers at the extreme south of Italy in Sicily (30%). The majority of Sardinians belong to Mesolotich European haplogroup I2a1a.^[5][6]

A Università Cattolica del Sacro Cuore study found that while Greek colonization left little significant genetic contribution, data analysis sampling 12 sites in the Italian peninsula supported a male demic diffusion model and Neolithic admixture with Mesolithic inhabitants.^[7] The results supported a distribution of genetic variation along a North-South Axis and supported demic diffusion. South Italian samples clustered with South east and south central European samples, and Northern groups with West Europe.^[8][9]

A 2004 study by Semino et al. contradicted this study, and showed that Italians in North-central regions (like Tuscany and Emilia-Romagna) had a higher concentration of J2 than their Southern counterparts. North-central had 26.9% J2, whereas Calabria (a far Southern region) had 20.0%, Sardinia had 9.7% and Sicily had 16.7%.^[10]

Migration High Medieval Y-DNA

In Sicily further migrations from the Vandals, Normans and Saracens have only slightly affected the ethnic composition of the Sicilian people. Norman civilization proliferated for several centuries on the island, with a strong impact on the culture of the place and different populations as Normans, Bretons, Anglo-Saxons, Swabians and Lombards have repopulated the island with a male contribution around 8% (haplogroup I). The Norman Kingdom of Sicily was created in 1130, with Palermo as capital, and would last until the 19th century. Nowadays it is in north-west Sicily, around Palermo and Trapani, that Norman Y-DNA is the most common, with 8 to 15% of the lineages belonging to haplogroup I. In the thirteenth century Frederick II destroyed Arab rule in Sicily and between 1221 and 1226 he moved all the Arabs of Sicily to the city of Lucera in Italy. Ultimately, the North African male contribution to Sicily was estimated 6%.^[11][12]

Overall the frequency of pure Germanic paternal lineages (Norman, Vandal, Gothic, Lombard, Frankish, Swabian,...) varies from a minimum of 5-10 % to a maximum of 40-50 %. In the South the highest values are found in Western Sicily, Molise and in Campania (20-30%). There is also a hotspot of U106 in Catania.

A 2015 study found high frequencies (25-35%) of Germanic paternal lineages between eastern Latium and western Abruzzo.^[13]

Adding up Celtic paternal lineages like R-L21, P312*, SRY2627,... the total frequency of Celto-Germanic paternal lineages raises by 5-10% at least.^[14][15]

Genetic composition of Italians mtDNA

In Italy as elsewhere in Europe the majority of mtdna lineages belong to the haplogroup H. Several independent studies conclude that haplogroup H probably evolved in West Asia c. 25,000 years ago. It was carried to Europe by migrations c. 20-25,000 years ago, and spread with population of the southwest of the continent.^[16][17] Its arrival was roughly contemporary with the rise of the Gravettian culture. The spread of subclades H1, H3 and the sister haplogroup V reflect a second intra-European expansion from the Franco-Cantabrian region after the last glacial maximum, c. 13,000 years ago.^[18][16]

African Haplogroup L lineages are relatively infrequent (less than 1%) throughout Italy with the exception of Latium, Volterra, Basilicata and Sicily where frequencies between 2 and 3% have been found.^[19]

A study in 2012 by Brisighelli "et al." stated that an analysis of ancestral informative markers "as carried out in the present study indicated that Italy shows a very minor sub-Saharan African component that is, however, slightly higher than non-Mediterranean Europe." Discussing sub-Saharan African mtDNAs the study states that these indicate that a significant proportion of these lineages could have arrived in Italy more than 10,000 years ago; therefore, their presence in Europe does not necessarily date to the time of the Roman Empire, the Atlantic slave trade or to modern migration."^[1] These mtDNAs by Brisighelli "et al." were reported with the given results as "Mitochondrial DNA haplotypes of African origin are mainly represented by haplogroups M1 (0.3%), U6 (0.8%) and L (1.2%)" for the 583 samples tested.^[1]

A 2013 study by Alessio Boattini et al. found 0 of African L haplogroup in the whole Italy out of 865 samples. The percentages for Berber M1 and U6 haplogroups were 0.46% and 0.35% respectively.^[20]

A 2014 study by Stefania Sarno et al. found 0 of African L and M1 haplogroups in mainland Southern Italy out of 115 samples. Only two Berber U6 out of 115 samples were found, one from Lecce and one from Cosenza.^[21]

The contribution in rebuilding Europe's mtDNA

Recent studies have shown that Italy has played an important role in the recovery of 'Western Europe" at the end of the Last glacial period. The study focused mitochondrial U5b3 haplogroup discovered that this female lineage had in fact originated in Italy and that then expanded from the Peninsula around 10,000 years ago towards Provence and the Balkans. In Provence, probably between 9,000 and 7,000 years ago, it gave rise to the haplogroup subclade U5b3a1. This subclade U5b3a1 later came from Provence to the island of Sardinia by obsidian merchants, as it is estimated that 80% of obsidian found in France comes from Monte Arci in Sardinia reflecting the close relations that were at the time of these two regions. Still about 4% of the female population in Sardinia belongs to this haplotype.^[22]

Autosomal

• Recent genome-wide studies have been able to detect and quantify admixture like never before. Li et al. (2008), using more than 600,000 autosomal SNPs, identify seven global population clusters, including European, Middle Eastern and Central/South Asian. All the Italian samples belong to Central-Western group with minor influences dating to Neolitich period.^[23]

• López Herráez et al. (2009) typed the same samples at close to 1 million SNPs and analyzed them in a Western Eurasian context, identifying a number of subclusters. This time, all of the European samples show some minor admixture. Among the Italians, Tuscany still has the most, and Sardinia has a bit too, but so does Lombardy (Bergamo), which is even farther north.^[24]

• A 2012 study by Di Gaetano et al. presents the first analysis using the 125,799 genome-wide Single Nucleotide Polymorphisms (SNPs) data of 1,014 Italians with wide geographical coverage. It showed by using Principal Component analysis and model-based individual ancestry analysis, that the current population of Sardinia can be clearly differentiated genetically from mainland Italy and Sicily, and that a certain degree of genetic differentiation is detectable within the current Italian peninsula population. Pair-wise FST statistics Northern and Southern Italy amounts approximately to 0.001 between, and around 0.002 between Northern Italy and Utah residents with Northern and Western European ancestry (CEU).

By using the ADMIXTURE software, the authors obtained at K = 4 the lowest cross-validation error. The HapMap CEU individuals showed an average Northern Europe (NE) ancestry (light green) of 83%. A similar pattern is observed in French, Northern Italian and Central Italian populations with a NE ancestry of 70%, 56% and 52% respectively (Figure 3). According to the PCA plot, also in the ADMIXTURE analysis there are relatively small differences in ancestry between Northern Italians and Central Italians while Southern Italians showed a lower average admixture NE proportion (43,6%) than Northern and Central Italy, and a higher Middle East ancestry (light blue) of 28%. The Sardinian samples display a pattern of crimson common to the others European populations but at a higher frequency (70.4%).

The average admixture proportions for Northern European ancestry within current Sardinian population is 14.3% with some individuals exhibiting very low Northern European ancestry (less than 5% in 36 individuals on 268 accounting the 13% of the sample).^[25]

• A 2013 study by Peristera Paschou et al. confirms that the Mediterranean Sea has acted as a strong barrier to gene flow through geographic isolation following initial settlements. Samples from (Northern) Italy, Tuscany, Sicily and Sardinia are closest to other Southern Europeans from Iberia, the Balkans and Greece, who are in turn closest to the Neolithic migrants that spread farming throughout Europe, represented here by the Cappadocian sample from Anatolia. But there hasn't been any significant admixture from the Middle East or North Africa into Italy and the rest of Southern Europe since then.^[26]

• Ancient DNA analysis reveals that Ötzi the Iceman clusters with modern Southern Europeans and closest to Italians (the orange "Europe S" dots in the plots below), especially those from the island of Sardinia. Other Italians pull away toward Southeastern and Central Europe consistent with geography and some post-Neolithic gene flow from those areas (e.g. Italics, Greeks, Etruscans, Celts), but despite that and centuries of history, they're still very similar to their prehistoric ancestor.^[27]

See also

• Genetic history of Europe
• European ethnic groups

References