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. 2014 Sep 17;9(9):e105920.
doi: 10.1371/journal.pone.0105920. eCollection 2014.

A Genome-Wide Study of Modern-Day Tuscans: Revisiting Herodotus's Theory on the Origin of the Etruscans

Free PMC article

A Genome-Wide Study of Modern-Day Tuscans: Revisiting Herodotus's Theory on the Origin of the Etruscans

Jacobo Pardo-Seco et al. PLoS One. .
Free PMC article


Background: The origin of the Etruscan civilization (Etruria, Central Italy) is a long-standing subject of debate among scholars from different disciplines. The bulk of the information has been reconstructed from ancient texts and archaeological findings and, in the last few years, through the analysis of uniparental genetic markers.

Methods: By meta-analyzing genome-wide data from The 1000 Genomes Project and the literature, we were able to compare the genomic patterns (>540,000 SNPs) of present day Tuscans (N = 98) with other population groups from the main hypothetical source populations, namely, Europe and the Middle East.

Results: Admixture analysis indicates the presence of 25-34% of Middle Eastern component in modern Tuscans. Different analyses have been carried out using identity-by-state (IBS) values and genetic distances point to Eastern Anatolia/Southern Caucasus as the most likely geographic origin of the main Middle Eastern genetic component observed in the genome of modern Tuscans.

Conclusions: The data indicate that the admixture event between local Tuscans and Middle Easterners could have occurred in Central Italy about 2,600-3,100 years ago (y.a.). On the whole, the results validate the theory of the ancient historian Herodotus on the origin of Etruscans.

Conflict of interest statement

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


Figure 1
Figure 1. PCA of TSI and samples representing main continental groups, including Africa (AFR; represented by YRI), East Asia (EAS; represented by CHB), broad Middle East (bMEA), and Europe (EUR; represented by CEU+GBR+IBS+SPA) (Figure 1A) and PCA comparing only TSI, EUR and different populations from bMEA (Figure 1B).
For each PCA analysis, only three principal components are represented (PC1 vs. PC2, and PC1 vs. PC3). See Table 1 for more information on population codes.
Figure 2
Figure 2. Weir and Cockerham's individual SNP FST values (the whiskers range from the lowest datum still within 1.5 IQR of the lower quartile [equals to 0 in this case], and the highest datum still within 1.5 IQR of Q3) between TSI vs. EUR and populations from bMEA (Figure 2A).
The populations are sorted from the lowest to the highest average FST values against TSI (indicated for each population in the top of each FST distribution). PCA plots of individual SNP FST values considering all populations from bMEA (Figure 2B), and the same PCA after eliminating SAM from the analysis (Figure 2C).
Figure 3
Figure 3. Bar-plot of individual ancestries as computed using the unsupervised clustering algorithm implemented in ADMIXTURE.
Figure 3A considered TSI and main continental groups, AFR, EAS, EUR, and bMEA, with K = 4 being the lowest cross validation value. Figure 3B considered TSI against EUR and the different populations from bMEA, with K = 2 as the optimal cross validation value.
Figure 4
Figure 4. Density curves of intra- and inter-population IBS values for EUR, bMEA and TSI.
Figure 5
Figure 5. Average IBS values between TSI individuals and individuals from EUR and other bMEA populations.
IBS values were arranged from the lowest averages with TSI (namely, ARM) to the highest.
Figure 6
Figure 6. Estimates of the age of admixture in TSI considering EUR and bMEA as the two source populations (7A) and considering EUR and a sample that merges the datasets from Turkey (TRK, SHP) and South Caucasus (ARM, GRG, AZR, and LZG).
All the estimates were statistically significant under the ad hoc z test carried out by ALDER.
Figure 7
Figure 7. The migration model aims to explain the origin of Etruscans accommodating the different findings reported on mtDNA studies and those observed in the present study.
The map shows FST interpolated values between TSI and Middle Eastern populations (no European datasets were considered here) with colors ranging from dark green (lowest values) to yellow (highest values). The non-colored map regions were not interpolated.

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Grant support

The research leading to these results has received funding from the “Ministerio de Ciencia e Innovación” (SAF2011-26983) and from the Plan Galego IDT, Xunta de Galicia (EM 2012/045) (A.S.) and Consellería de Sanidade/Xunta de Galicia (RHI07/2-intensificación de la actividad investigadora and 10PXIB918184PR), Instituto Carlos III (Intensificación de la actividad investigadora) and Fondo de Investigación Sanitaria (FIS; PI07/0069, PI10/00540 and PI13/02382) of the Plan Nacional de I+D+I and ‘fondos FEDER’ (F.M.T.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.