Italian genomes mirror the multilayer history of Southern Europe

The cultural diversity that characterises Italy is appreciated by millions of people every year. Such variety is reflected in the several languages and dialects, traditional foods and customs present across the “Bel Paese” that originated from local dynamics and influences from nearby regions over the last few millennia. Facilitated by the peninsula being a natural crossroad between mainland Europe and the Mediterranean Sea, this richness has now been shown to be mirrored also in the DNA of the Italians, where the combination of several genetic “layers” have shaped the variation displayed by people living in the country.

In a new study led by Dr Cristian Capelli of the Department of Zoology, the team of scientists from across Europe, the Middle East and North Africa have recovered and characterised the genetic signatures of past migrations and subsequent events of gene-flow that shaped the genetic history of Italy and surrounding regions. 

The team found evidence that Italy, and especially the southernmost regions, harbours a signature of a layer additional to the three ancestral groups usually reported (Mesolithic hunter-gatherers, Neolithic farmers and Bronze Age Nomadic Pastoralists) that might be genetically related to modern-day Caucasus populations. This novel component might have occurred at the end of the Neolithic or at the beginning of the Bronze Age. Contributions from the African continent in historical times further enriched the genetic diversity of the Italians, who show a degree of variation larger than any other European country tested so far and comparable to variation observed across Europe. Interestingly, variation across Europe and Italy also extended to the amount of Neanderthal DNA present in the genome of modern-day populations, with groups in the North having more DNA inherited from our evolutionary cousins that populations from the South of the continent. 

There are several reasons, however, why this data should not be used to manipulate arguments for or against national identity. First, the actual differences among European groups is a small fraction of the total variation present in humans, which in turn is less than 0.1%. The bulk of human variation is shared across groups and only miniscule fractions differ between them. 

Second, the genetic variability in Europe follows a pattern related to longitude and latitude, and do not mirror the political borders we are familiar with, that are instead a very recent historical development. 

Third, these investigations have demonstrated that the history of Europe and Italy is a continuous and fluid combination of movements and admixture that involved several populations, resident and incoming, which mixed once they came into contact. Put it simply, all modern Italians (as any other population) are different from the people that were inhabiting the same area a few millennia ago as the result of ancient and historical gene-flow.

The identification of an additional unexpected ancient contribution requires now the characterisation of its sources and the definition of the chronology of its dispersal. Capelli and collaborators are currently focusing on modern populations in the South of Italy to further clarify the impact of this contribution and investigating ancient Italian samples to time will help to clarify its appearance along the peninsula.

The paper, published in Science Advancescan be read here.

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