# At the Crossroads of Continents: Ancient DNA Insights into the Maternal and Paternal Population History of Croatia

## TL;DR

Ancient DNA from Croatia reveals consistent maternal genetic patterns over time, while paternal lineages show more change due to migrations.

## Contribution

The study provides new ancient genome data from Croatia, revealing genetic continuity in maternal lineages and shifts in paternal haplogroups over millennia.

## Key findings

- Maternal haplogroups H, U, and HV0 show continuity from prehistoric to modern times.
- Paternal haplogroups J, R1a, and I2a increased in frequency over time, indicating population shifts.
- Ancient Croatian genetic patterns align with broader European and Near Eastern trends.

## Abstract

Background/Objectives: Southeastern Europe and Croatia have served as a genetic crossroads between the Near East and Europe since prehistoric times, shaped by numerous and repeated migrations. By integrating 19 newly generated ancient genomes with 285 previously published ancient genomes from Croatia, we investigated patterns of maternal and paternal landscapes from the Neolithic, Bronze, and Iron Ages through to the Antiquity and medieval periods, as well as the modern Croatian population. Methods: Ancient DNA extraction from human remains and library preparation were conducted in dedicated clean-room facilities, followed by high-throughput sequencing on the Illumina platform. Sequencing data were analyzed with established pipelines to determine mitochondrial and Y-chromosomal haplogroups and the genetic sex of individuals. Results: New ancient data reveal a predominantly European maternal profile, dominated by haplogroups H, U, and HV0, whereas Y-chromosomal lineages are characterized by J subclades and R1a, with limited representation of R1b and the absence of I2a. When combined with published ancient Croatian genomes, the results reveal similar haplogroup diversity and patterns, as well as the expansion of mtDNA haplogroup H over time and a substantial increase in Y-chromosome R1a and I2a haplogroup frequency from the prehistoric to the modern period. Conclusions: Although the analyzed samples are heterogeneous and originate from different historical periods, their genetic signatures conform to the broader patterns expected for the region. In a wider context, the ancient Croatian mitochondrial data reveal stronger genetic persistence from prehistory to modern times, unlike paternal lineages, which show significantly higher divergence.