Kristiina Tambets1, Alena Kushniarevich1, Toomas Kivisild2, Fernando Racimo3, Rimantas Jankauskas4 & Gunita Zariņa5
1University of Tartu
2Katholieke Universiteit Leuven
3University of Copenhagen
4Vilnius University
5University of Latvia
Aims of the ECHO project
A comprehensive understanding of the human past demands close collaboration across diverse scientific disciplines and a high level of analytical expertise. Recognizing these needs, the ECHO project brings together archaeologists, geneticists, and anthropologists from Estonia, Latvia, and Lithuania, while partnering with leading research centres in Belgium and Denmark. This joint effort aims to build a network of experts, data, and skills to uncover new insights into human evolution and cultural transformations and to learn about the mostly unexplored post-Bronze Age period in the Eastern Baltic region.
Our team
To achieve the objectives of the ECHO project, the Archaeogenomics research group at the Institute of Genomics, University of Tartu (coordinator of the project) collaborates with two internationally renowned European research institutions: KU Leuven in Belgium and the University of Copenhagen in Denmark. This partnership facilitates the transfer of cutting-edge analytical methodologies for investigating key questions about human evolutionary history. It will enhance the expertise of Baltic partners in the integration and analysis of multiple data types, in analysing degraded ancient DNA, and detecting signals of natural selection. Within ECHO, workshops to improve the data analysis skills on those topics will be organised for a wider audience by the partners.
In addition to strengthening methodological capacity, the project aims to establish a pan-Eastern Baltic network that connects the expertise and resources of leading research institutions in Estonia (University of Tartu), Latvia (University of Latvia), and Lithuania (Vilnius University). This network will foster close interdisciplinary collaboration between humanities and natural sciences in the Eastern Baltic to study the human past across the region.
ECHO’s main objectives
- To extend the methodological expertise of researchers and students in the Eastern Baltics through various trainings led by experts from KU Leuven and University of Copenhagen.
- To develop constructive communication between specialists from the natural sciences and humanities in the Eastern Baltics through trainings, joint activities, and by establishing long-term collaborations.
- To carry out a Pilot Research Project as an interdisciplinary cooperation of stakeholders in the Eastern Baltic region.
A key element of our twinning strategy is a joint research project on the Post-Bronze-Age population history in the Eastern Baltic region from an ancient DNA perspective.
Background
There are various drivers (migration, natural selection, drift, etc.) that affect the genetic structure of human populations by changing the frequencies of alleles and reshuffling genetic ancestry components of populations. The mode of human mobility has varied substantially across time depending on both natural (ecological niche, availability of resources, climate) and cultural aspects (subsistence strategies, technological change, diffusion of languages, etc.). Knowing the dynamics and regional specificity of human movements and interactions over time is one of the keys to understanding today's genetic and cultural diversity (Marnetto et al. 2022; Haak et al. 2015; Allentoft et al. 2015; Mathieson et al. 2015; Lazaridis et al. 2014).
Along with the three major genetic ancestries (hunter-gatherer-, farmer- and steppe-like) that contribute to the genomes of most of today’s European populations, there is also a minor, so-called Siberian-like genetic component that is present in the genomes of northeastern European populations (Tambets et al. 2018; Kasperavičiūtė et al. 2004; Rootsi et al. 2006). The arrival of this ancestry component dates to the transition period from the Bronze to the Iron Age ca. 2500 years ago and is thought to be connected to the spread of Uralic-Finnic languages in the Eastern Baltic territory (Saag et al. 2019). The Bronze to Iron Age transition and subsequent periods witnessed significant and diverse changes to the material and cultural landscapes of the Eastern Baltics. This includes migration waves and cultural influences that contributed to the spread of the Baltic, Finnic and Slavic languages (Lang 2018; Grünthal et al. 2022). These possibly involved population influx from the east and large-scale movements during the Migration Period either through population contacts with Roman provinces to the south along the ancient trade routes or in the north during the Viking Age (Margarian et al. 2020).
The first millennium AD in the Baltics is characterized by the more extensive use of iron. It also included increased agricultural productivity, which resulted in population growth, social stratification, and emerging social/territorial organizations led by emerging elites. However, it is not clear to what extent differences in social status were heritable, as in Western Europe (Rott et al. 2017). The impact of later processes on the genetic composition of the region remains unclear, notwithstanding evidence of direct contacts already in antiquity (Reitsema et al. 2022).
Taking into account the importance of the post-Bronze-Age period in the formation of genetic and cultural diversity as well as the scarce data about the population genetic processes for the Eastern Baltics, our research project within ECHO aims to contribute to the understanding of the causes, consequences, and modes of demographic processes and adaptations in the region over the last three millennia. Importantly, we will concentrate on the period of the Late Iron Age for which bioarchaeological samples are available from all Baltic partners.
Research objectives and hypotheses
The project aims to uncover the fine-scale genetic structure and demographic dynamics of Iron Age populations in the Eastern Baltic region. It integrates archaeological, ecological, and paleoclimatic data to better understand long-term human-environment interactions. The project’s principal objectives and associated hypotheses can be summarized thusly:
Objective 1: Characterization of genetic structure in the Iron Age of the Eastern Baltic
Hypothesis 1.1: Genetic differences between Late Iron Age populations reflect cultural distinctions between northern and southern Eastern Baltic communities.
Hypothesis 1.2: Social status, as inferred from burial customs, was heritable within Iron Age societies.
To test our hypotheses, we will shotgun-sequence approximately 300 new ancient human DNA samples from the Eastern Baltic, spanning the Iron Age to the Medieval period. About half of these individuals originate from Plinkaigalis, a unique Iron Age archaeological site in Lithuania that provides an exceptional opportunity to explore patterns of social organization in the region. Each genome will be complemented with a detailed archaeological context.
We will perform genotype imputation using available tools (Davies et al., 2021; Rubinacci et al., 2021), allowing for more comprehensive downstream analyses.
We will characterize the genetic structure of the newly sequenced individuals in the context of published ancient and modern genomes using approaches published elsewhere (Kivisild et al., 2021; Ringbauer et al., 2023). We anticipate that the population structure of the Iron Age Eastern Baltic will reflect geographical patterns similar to those seen among present-day populations.
A detailed analysis of biological kinship, social structure, and burial practices will focus on individuals from the Plinkaigalis burial site in central Lithuania. Using methods such as READ (Kuhn et al., 2018) and IBD-based kinship inference (Ringbauer et al., 2023), we aim to test whether patterns of biological relatedness in the Iron Age Eastern Baltic correlate with indicators of social status.
Objective 2: Demographic modelling across time and space
Hypothesis 2.1: Climate change and resource availability were key drivers of human migration during the Late Bronze Age and Early Iron Age in Eastern Europe.
Hypothesis 2.2: The genetic structure of Iron Age populations in the Eastern Baltics developed largely in situ, with minimal external genetic input.
Here, we will integrate multiple types of data, including genetic, archaeological (radiocarbon chronologies and stable isotope analyses), geographical, and environmental, into a unified dataset.
We will test the demographic inferences obtained in Objective 1 using the non-spatial slendr
framework (Petr et al., 2023) and extend these analyses with spatiotemporal modelling to reconstruct migration dynamics across space and time. Together, these approaches will help identify potential drivers of human mobility in the Eastern Baltic over the past two millennia.
Objective 3: Human adaptation to environment and subsistence
Hypothesis 3.1: Phenotype-related genetic variants are influenced by ancestry components, such as the ‘Siberian’ component differing across Baltic subregions.
Hypothesis 3.2: Variations in exposure to infectious diseases and subsistence strategies have shaped allele frequencies related to immunity, metabolism, and other traits.
Here, we will analyse allele frequency of the variants associated with various phenotypic traits (immunity, metabolism) and inspect changes in frequencies in ancient and modern individuals from the Eastern Baltic as an indication of selection (Speidel et al., 2019; Stern et al., 2019; Marnetto et al., 2022; Margaryan et al., 2020). By comparing ancient and modern datasets and integrating archaeological and palaeoenvironmental information, we will explore how differences in subsistence strategies have influenced genetic adaptation in the region over time.
ECHO is a three-year project (2025-2027) led by Prof. Kristiina Tambets (University of Tartu, Estonia). It is supported by the Widening Participation and Spreading Excellence actions under Horizon Europe 4.1 programme under the Twinning Bottom-Up topic. To learn more about the project and its activities or to contact us, please visit the project webpage.
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