italian genetic

Exploring the origins of genetic divergence within the Italian population

Genetic adaptations of early Italian ancestors to environmental changes, such as those that occurred soon after the Last Glacial Maximum, may explain some of the genetic differences between northern and southern Italian populations today, according to a study published in BMC Biology. The research suggests that northern and southern Italian populations may have begun to diverge genetically as early as 19,000-12,000 years ago and constitutes the earliest known evidence of genetic divergence in Italy so far.

A team of researchers at the University of Bologna sequenced the genomes of 38 unrelated participants from different regions in Italy, each the third generation of their family native to each region. The genomes were selected as representative of known genetic differences across the Italian population and over 17 million distinct genetic variants were found between individuals. The authors compared these variations with existing genetic data from 35 populations across Europe and the Mediterranean and with variants previously observed in 559 ancient human remains, dating from the Upper Palaeolithic (approx. 40,000 years ago) to the Bronze Age (approx. 4,000 years ago).

Prof. Marco Sazzini, lead author of the study said: “When comparing sequences between modern and ancient genome samples, we found early genetic divergence between the ancestors of northern and southern Italian groups dating back to the Late Glacial, around 19,000-12,000 years ago. Migrations during the Neolithic and Bronze Age periods, thousands of years later, then further differentiated their gene pools. Divergence between these ancestral populations may have occurred as a result of temperature rises and subsequent shrinking of glaciers across Northern Italy during this time, allowing ancestors who survived the glaciation period to move north, separating from groups who remained in the south.”

Further analyses also revealed signatures ascribable to specific biological adaptations in northern and southern Italian genomes suggestive of habitation in differing climates. The genetic history of northern Italians showed changes in the genes responsible for regulating insulin, body-heat production and fat metabolism, whilst southern Italians showed adaptations in genes regulating the production of melanin and responses to pathogens.

Prof. Sazzini said: “Our findings suggest that the ancestors of northern Italians adapted to lower environmental temperatures and the related high-calorie diets by optimising their energy metabolism. This adaptation may play a role in the lower prevalence of Type 2 Diabetes recorded in Northern Italy today. Conversely, southern Italian ancestors adapted to a warmer climate with higher UV levels by increasing melanin production, which may explain the lower incidence rates of skin cancers recorded across Southern regions. The genomes of southern Italians also showed changes in the genes encoding mucins, which play a role in protection against pathogens, and genetic variants linked to a longer lifespan. Further research in this area may help us understand how the observed genetic differences can impact population health or predisposition to a number of diseases.”

The authors caution that although correlations may be drawn between evolutionary adaptations and current disease prevalence among populations, they are unable to prove causation, or rule out the possibility that more recent gene flow from populations exposed to diverse environmental conditions outside of Italy may have also contributed to the different genetic signatures seen between northern and southern Italians today.

 

italian genetic
Adaptive events evolved by ancestors of N_ITA/S_ITA clusters and their health implications for present-day Italians. The putative selective pressures having plausibly prompted local adaptations are displayed on the left, while biological processes subjected to natural selection are reported on the map along with their impact on present-day disease susceptibility. Distribution of biological adaptations having the potential to modulate the longevity phenotype (e.g., involving the mTOR signaling, arachidonic acid metabolism, and FoxO signaling pathways) in the overall Italian population, but especially in people from Southern Italy, is represented by the arrow on the right. Putative selective pressures, biological processes, and distribution of adaptations potentially modulating longevity are color-coded as follows: N_ITA, blue; S_ITA, red. Picture from the paper, credits Sazzini, M., Abondio, P., Sarno, S. et al., CC BY 4.0

Sazzini, M., Abondio, P., Sarno, S. et al. Genomic history of the Italian population recapitulates key evolutionary dynamics of both Continental and Southern Europeans. BMC Biol 18, 51 (2020). https://doi.org/10.1186/s12915-020-00778-4

 

Press release from Springer.


Cenomani Gauls Verona Seminario Vescovile

Funerary customs, diet, and social behavior in a pre-Roman Italian Celtic community

Funerary customs, diet, and social behavior in a pre-Roman Italian Celtic community

Cenomani Gauls Verona Seminario Vescovile
Localization of main Celtic necropolises of Italy and examples of burials from SV. Credit: Laffranchi et al, 2019

Analysis of human remains from a Pre-Roman Celtic cemetery in Italy shows variations in funerary treatment between individuals that could be related to social status, but these variations were not reflected by differences in their living conditions. Zita Laffranchi of Universidad de Granada, Spain, and colleagues present these new findings in the open access journal PLOS ONE on April 17, 2019.

Archeological and written evidence have provided scant insight into social organization among the Cenomani Gauls, Celtic people who began to spread into Northern Italy in the 4th century BC. In a preliminary step to address this knowledge gap, Laffranchi and colleagues analyzed remains from Verona - Seminario Vescovile, a Cenomani burial site that was used between the 3rd and 1st centuries BC.

Seminario Vescovile features some variety in funerary approaches. Some individuals were buried face up, face down, or on their sides; some with animals; and some with varying amounts and types of objects, such as pottery and decorations. Focusing on 125 individuals buried at the site, the researchers set out to explore links between funerary treatment, age, sex, and diet--the first such study for Cenomani Gauls.

Bone analysis revealed different carbon and nitrogen isotope levels between sexes, indicating that men and women at Verona-Seminario Vescovile had different diets. Tooth analysis suggests that the population had higher rates of dental enamel defects than did other Pre-Roman and Celtic groups of the Italian Peninsula, pointing to higher physiological stress levels during childhood.

The researchers were surprised to find no differences between sexes in funerary treatment. They also found no links between funerary differences and isotope measurements or enamel defects. Increased age was somewhat related to increased number of grave objects, but age and burial position were not linked. These findings suggest the existence of weak social differentiation that could have influenced funerary treatment, but that, apart from different diets for men and women, individuals in the group shared similar living conditions.

The authors conclude that the individuals they analyzed were likely members of a homogeneous and potentially low-status group within the original population. Still, they call for extensive additional research to clarify the implications of their findings.

The authors add: "This is the first combined study of diet, developmental stress, and funerary patterns in a Celtic community from the Italian peninsula: the little known Cenomani (North-Eastern Italy)."

###

Citation: Laffranchi Z, Cavalieri Manasse G, Salzani L, Milella M (2019) Patterns of funerary variability, diet, and developmental stress in a Celtic population from NE Italy (3rd-1st c BC). PLoS ONE 14(4): e0214372. https://doi.org/10.1371/journal.pone.0214372

Funding: The authors received no specific funding for this work.

Competing Interests: The authors have declared that no competing interests exist.

 

Press release from Public Library of Science (PLOS)