The Genetic Origin of Daunians and the Pan-Mediterranean Southern Italian Iron Age Context

Abstract

The geographical location and shape of Apulia, a narrow land stretching out in the sea at the South of Italy, made this region a Mediterranean crossroads connecting Western Europe and the Balkans. Such movements culminated at the beginning of the Iron Age with the Iapygian civilization which consisted of three cultures: Peucetians, Messapians, and Daunians. Among them, the Daunians left a peculiar cultural heritage, with one-of-a-kind stelae and pottery, but, despite the extensive archaeological literature, their origin has been lost to time. In order to shed light on this and to provide a genetic picture of Iron Age Southern Italy, we collected and sequenced human remains from three archaeological sites geographically located in Northern Apulia (the area historically inhabited by Daunians) and radiocarbon dated between 1157 and 275 calBCE. We find that Iron Age Apulian samples are still distant from the genetic variability of modern-day Apulians, they show a degree of genetic heterogeneity comparable with the cosmopolitan Republican and Imperial Roman civilization, even though a few kilometers and centuries separate them, and they are well inserted into the Iron Age Pan-Mediterranean genetic landscape. Our study provides for the first time a window on the genetic make-up of pre-Roman Apulia, whose increasing connectivity within the Mediterranean landscape, would have contributed to laying the foundation for modern genetic variability. In this light, the genetic profile of Daunians may be compatible with an at least partial autochthonous origin, with plausible contributions from the Balkan peninsula.

Keywords: Dauni. Iron Age; Southern Italy; ancient DNA.

Fig. 1.

Geographical location, dating, and genetic structure. (A) Geographical location of the newly generated Apulian ancient individuals (green, red, and blue diamonds and triangles) and other published Iron Age samples from Italy and surrounding areas (color scale mirroring their “years before present” dates). (See also table 1 and supplementary data 1 and 2, Supplementary Material online.) (B) Dating and number of SNPs from 1240K set covered. Samples with thick edges have been radiocarbon dated (mean presented), whereas for the others, we represented their archaeological dating (table 1 and supplementary data 1B, Supplementary Material online). (C) PCA of newly generated individuals with reference ancient individuals projected onto the genetic variation inferred from modern-day Western Eurasian populations (supplementary data 2 and 3, Supplementary Material online). For the ancient reference populations which have not been attributed to the Iron Age, we plotted their centroids.

Fig. 2.

Genetic relationship of Iron Age and Middle Age Apulians and their ancestral composition. (A) Heatmap representing the Z score values of f4(Modern Apulia, IAA; X, Mbuti), where X is an ancient Italian population. We also added the two Middle Age samples for comparison. Tests with Z scores between −3 and 3 or with less than 5,000 SNPs were not included (P, Palaeolithic; M, Mesolithic; N, Neolithic; C, Chalcolithic; CA, Copper Age; BA, Bronze Age; IA, Iron Age; A, Antiquity). (B) qpAdm proportions of ancient Apulian samples and other reference populations (Modern Apulians, Minoans, Croatia_EIA, and the Roman individuals from the Republican and the Imperial period) using “base” sources: Caucasus and Western hunter-gatherer component (HG), Anatolia Neolithic (Anatolia_N), Iranian Neolithic (Iran_N), Steppe-related ancestry. (C) qpAdm proportions using also the Minoans as source (Materials and Methods). In (B) and (C), we plotted the model with the highest number of sources and P value (complete results may be seen in supplementary fig. 7, Supplementary Material online).

Fig. 3.

Genetic affinities of Iron Age Apulian samples with the putative populations of origin: Minoans (Minoan_Lassithi), Illyrians (here proxied by the Croatia_EIA individual), and the Roman Republicans (here proxying the autochthonous Iron Age Italian ancestry). (A) Outgroup f3 statistics of IAA samples compared with the putative Daunian sources. Samples have been sorted and grouped according to the source whose f3 values were higher. (B) Heatmap showing the Z score values of f4(putative sources, IAA_P; X, Mbuti), where X is an ancient Italian population and IAA_P is the entire set of Iron Age Apulian samples taken together. Tests with Z scores between −3 and 3 or with less than 5,000 SNPs were not included (P, Palaeolithic; M, Mesolithic; N, Neolithic; C, Chalcolithic; CA, Copper Age; BA, Bronze Age; IA, Iron Age; A, Antiquity).