Mummified SHEEP discovered in Iranian salt mine with perfectly preserved soft tissues

The mummified remains of a sheep have been discovered in a salt mine in Iran, and it has perfectly preserved soft tissue still attached to the bone, according to experts. 

An international team of geneticists and archaeologists sequenced DNA from the 1,600-year-old sheep mummy found at the ancient Iranian Chehrābād salt mine, about 230 miles from Tehran in the Zanjan Province.

It revealed sheep husbandry practices the time, and how natural mummification can degrade DNA, according to the team led by geneticists from Trinity College Dublin  

This natural process, where water is removed from a corpse, preserving soft tissues that would otherwise be degraded, has been seen in human remains from the mine.

While ancient DNA is usually damaged and fragmented, making it hard to study, the team found that this sheep mummy DNA had been ‘extremely well preserved’.

There were longer length fragments of DNA and less damage than would be associated with the remains of something 1,600 years old. 

This is what allowed them to study the remains in greater detail, including giving an insight into the ancient sheep husbandry processes and pests present at the time. 

The mummified sheep leg. The mummified remains of a sheep have been discovered in a salt mine in Iran, and it has perfectly preserved soft tissue still attached to the bone, according to experts

The Chehrābād salt mine is known to preserve biological material through a natural process due to the salt rich environment, including the ‘Salt Men’.

The first remarkably well preserved salt man was discovered in 1993, dating back 1.700 years, and others have since been found with tissue and clothing in tact.  

The new research confirms that the natural mummification process that occurs in the mine also conserved animal remains.

The research team exploited this by extracting DNA from a small cutting of mummified skin from a leg recovered in the mine.

Microscopic examining of the DNA and hairs  revealed sheep husbandry practices the time, and how natural mummification can degrade DNA

Microscopic examining of the DNA and hairs  revealed sheep husbandry practices the time, and how natural mummification can degrade DNA

While ancient DNA is usually damaged and fragmented, making it hard to study, the team found that this sheep mummy DNA had been 'extremely well preserved'

While ancient DNA is usually damaged and fragmented, making it hard to study, the team found that this sheep mummy DNA had been ‘extremely well preserved’

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, the team explained.

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.

The mummified animal was genetically similar to modern sheep breeds from the region, the team discovered.

An international team of geneticists and archaeologists sequenced DNA from the 1,600-year-old sheep mummy found at the ancient Iranian Chehrābād salt mine, about 230 miles from Tehran in the Zanjan Province

An international team of geneticists and archaeologists sequenced DNA from the 1,600-year-old sheep mummy found at the ancient Iranian Chehrābād salt mine, about 230 miles from Tehran in the Zanjan Province

This suggests that there has been a continuity of ancestry of sheep in Iran since at least 1,600 years ago, but that could go back further.

‘Mummified remains are quite rare so little evidence was known about the survival of ancient DNA in these tissues prior to this study,’ says lead author Conor Rossi. 

‘The astounding integrity of the DNA was not like anything we had encountered from ancient bones and teeth before,’ the PhD student explained. 

‘This DNA preservation, coupled with the unique metagenomic profile, is an indication of how fundamental the environment is to tissue and DNA decay dynamics.’

The group attributes this to the mummification process, with the salt mine providing conditions ideal for preservation of animal tissues and DNA

The group attributes this to the mummification process, with the salt mine providing conditions ideal for preservation of animal tissues and DNA

The mummified animal was genetically similar to modern sheep breeds from the region, the team discovered

The mummified animal was genetically similar to modern sheep breeds from the region, the team discovered

The team also exploited the sheep’s DNA preservation to investigate genes associated with a woolly fleece and a fat-tail – two economic traits in sheep. 

Some wild sheep – the asiatic mouflon – are characterised by a ‘hairy’ coat, much different to the woolly coats seen in many domestic sheep today. 

Fat-tailed sheep are also common in Asia and Africa, where they are valued in cooking, and where they may be well-adapted to arid climates.

The team built a genetic impression of the sheep and discovered that the mummy lacked the gene variant associated with a woolly coat.

Fibre analysis using Scanning Electron Microscopy found the microscopic details of the hair fibres were consistent with hairy or mixed coat breeds. 

The team also exploited the sheep's DNA preservation to investigate genes associated with a woolly fleece and a fat-tail – two economic traits in sheep

The team also exploited the sheep’s DNA preservation to investigate genes associated with a woolly fleece and a fat-tail – two economic traits in sheep

The team built a genetic impression of the sheep and discovered that the mummy lacked the gene variant associated with a woolly coat

The team built a genetic impression of the sheep and discovered that the mummy lacked the gene variant associated with a woolly coat

The mummy carried genetic variants associated with fat-tailed breeds, suggesting the sheep was similar to the hairy-coated, fat-tailed sheep seen in Iran today.

Dr Kevin G Daly supervised the study, sand said genetic and microscopic approaches, when combined, allows for a more detailed study.

It allowed the team to create a ‘genetic picture of what sheep breeds in Iran 1,600 years ago may have looked like and how they may have been used.

‘Using cross-disciplinary approaches we can learn about what ancient cultures valued in animals, and this study shows us that the people of Sasanian-era Iran may have managed flocks of sheep specialised for meat consumption, suggesting well developed husbandry practices.’

The findings have been published in the journal Biology Letters. 

WHEN DID HUMANS START FARMING?  

It is widely known that farming and the development of agricultural skills allowed humans to move from being hunter-gatherers to a functioning society. 

Many tools have been found dating back thousands of years but the earliest recorded evidence of the changeover may have been founding Turkey. 

Urine sample analysis found a boom in population numbers and density 10,000 years ago. 

The oldest layers at the site that had any evidence of human habitation date back 10,400 years.

For 40 years only a slight increase in urine concentration was detected before a sudden spike lasting for 300 years, the researchers detected.