A team of geneticists and archaeologists has sequenced the DNA from a 1,600-year-old sheep mummy from an ancient Iranian salt mine, Chehrabad. This remarkable specimen has revealed sheep husbandry practices of the ancient Near East, as well as underlining how natural mummification can affect DNA degradation.

The incredible findings have just been published in the international, peer-reviewed journal Biology Letters.

The salt mine of Chehrabad is known to preserve biological material. Indeed, it is in this mine that human remains of the famed «Salt Men» were recovered, dessicated by the salt-rich environment. The new research confirms that this natural mummification process — where water is removed from a corpse, preserving soft tissues that would otherwise be degraded — also conserved animal remains.

The research team, led by geneticists from Trinity College Dublin, exploited this by extracting DNA from a small cutting of mummified skin from a leg recovered in the mine.

While ancient DNA is usually damaged and fragmented, the team found that the sheep mummy DNA was extremely well-preserved; with longer fragment lengths and less damage that would usually be associated with such an ancient age. The group attributes this to the mummification process, with the salt mine providing conditions ideal for preservation of animal tissues and DNA.

The salt mine’s influence was also seen in the microorganisms present in the sheep leg skin. Salt-loving archaea and bacteria dominated the microbial profile — also known as the metagenome — and may have also contributed to the preservation of the tissue.

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