Population genomic analysis of ancient and modern genomes yields new insights into the genetic ancestry of the Tyrolean Iceman and the genetic structure of Europe.

Martin Sikora,Albert Zink,Maristella Pitzalis,Carlo Sidore,Brenna M Henn,Ilenia Zara,Peter A Underhill,Andreas Keller,Nikola Theodossiev,Timothy T Harkins,Serena Sanna,Andrea Angius,Meredith L Carpenter,Georgi Nekhrizov,Frank Maixner,Chris Jones,Carlos D Bustamante,Andrea Maschio,Federico Sánchez-Quinto,Francesco Cucca,Fabio Busonero,Andrés Moreno‐Estrada ,Goncalo R Abeçasis ,Dessislava Dimitrova ,Javier Mendoza‐Revilla

doi:10.1371/journal.pgen.1004353

Abstract

Genome sequencing of the 5,300-year-old mummy of the Tyrolean Iceman, found in 1991 on a glacier near the border of Italy and Austria, has yielded new insights into his origin and relationship to modern European populations. A key finding of that study was an apparent recent common ancestry with individuals from Sardinia, based largely on the Y chromosome haplogroup and common autosomal SNP variation. Here, we compiled and analyzed genomic datasets from both modern and ancient Europeans, including genome sequence data from over 400 Sardinians and two ancient Thracians from Bulgaria, to investigate this result in greater detail and determine its implications for the genetic structure of Neolithic Europe. Using whole-genome sequencing data, we confirm that the Iceman is, indeed, most closely related to Sardinians. Furthermore, we show that this relationship extends to other individuals from cultural contexts associated with the spread of agriculture during the Neolithic transition, in contrast to individuals from a hunter-gatherer context. We hypothesize that this genetic affinity of ancient samples from different parts of Europe with Sardinians represents a common genetic component that was geographically widespread across Europe during the Neolithic, likely related to migrations and population expansions associated with the spread of agriculture.

Highlights

The Tyrolean Iceman is a well-preserved natural mummy that was discovered on a glacier near the Austrian-Italian border in 1991
This study was limited both by the availability of data from Sardinians and by a lack of genomic data from other ancient European samples
We use genomic data from modern Sardinians and from ancient European individuals from different geographic regions and cultural contexts, to demonstrate that this ancestry component is shared among individuals associated with the onset of agriculture in Europe

Summary

Introduction

The Tyrolean Iceman is a well-preserved natural mummy that was discovered on a glacier near the Austrian-Italian border in 1991. Subsequent analyses revealed that the remains were from a ,45-year-old male, with a 14C dating estimated age of 5,300 years, making it the oldest human mummy discovered in Europe to date [1,2,3]. In a principal component analysis including more than 1,300 Europeans, the Iceman clustered outside of the genetic variation of the continental Europeans and close to individuals from Sardinia. A previous study on bone and tooth stable isotope compositions concluded that the location of the Iceman’s origin could be restricted to a few valleys close to the discovery site [6], the question of whether this signal reflects an ancestry component

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