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Exceptional ancient DNA preservation and fibre remains of a Sasanian saltmine sheep mummy in Chehrābād, Iran

Published version
Peer-reviewed

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Authors

Ruß-Popa, Gabriela  ORCID logo  https://orcid.org/0000-0001-8492-6238
Mattiangeli, Valeria  ORCID logo  https://orcid.org/0000-0001-9785-1714
McDaid, Fionnuala 

Abstract

Mummified remains have long attracted interest as a potential source of ancient DNA. However, mummification is a rare process that requires an anhydrous environment to rapidly dehydrate and preserve tissue before complete decomposition occurs. We present the whole-genome sequences (3.94 X) of an approximately 1600-year-old naturally mummified sheep recovered from Chehrābād, a salt mine in northwestern Iran. Comparative analyses of published ancient sequences revealed the remarkable DNA integrity of this mummy. Hallmarks of postmortem damage, fragmentation and hydrolytic deamination are substantially reduced, likely owing to the high salinity of this taphonomic environment. Metagenomic analyses reflect the profound influence of high-salt content on decomposition; its microbial profile is predominated by halophilic archaea and bacteria, possibly contributing to the remarkable preservation of the sample. Applying population genomic analyses, we find clustering of this sheep with Southwest Asian modern breeds, suggesting ancestry continuity. Genotyping of a locus influencing the woolly phenotype showed the presence of an ancestral ‘hairy’ allele, consistent with hair fibre imaging. This, along with derived alleles associated with the fat-tail phenotype, provides genetic evidence that Sasanian-period Iranians maintained specialized sheep flocks for different uses, with the ‘hairy’, ‘fat-tailed’-genotyped sheep likely kept by the rural community of Chehrābād's miners.

Description

Funder: FP7 Ideas: European Research Council; Id: http://dx.doi.org/10.13039/100011199; Grant(s): 295729-CodeX

Keywords

Population genetics, Research articles, ancient DNA, sheep, mummy

Journal Title

Biology Letters

Conference Name

Journal ISSN

1744-957X

Volume Title

17

Publisher

The Royal Society
Sponsorship
H2020 European Research Council (787282-B2C)