Human DNA Extracted From Nits on Ancient Mummies Sheds Light on South American Ancestry

According to scientists, head lice found on ancient mummies contain more DNA than a tooth, which could shed light on ancient people and migration.

A team was able to extract the DNA from the ‘cement’ head lice used to glue their eggs to hairs on mummified bodies in South America, thousands of years ago.

A mummified adult man of the Ansilta culture, from the Andes of San Juan, Argentina, dating back approx 2,000 years

The DNA extracted from the cement was of better quality than that recovered through other methods, according to the team led by the University of Reading.

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It revealed clues about pre-Columbian human migration patterns throughout South America, including that the original population of the San Juan province migrated from the land and rainforests of the Amazon in the North of the continent.

‘There is a hunt out for alternative sources of ancient human DNA and nit cement might be one of those alternatives,’ said study first author Dr. Mikkel Winther Pederson, from the University of Copenhagen in Denmark.

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They recovered the DNA from head lice eggs, or nits, found in the hair of mummified bodies dating back 1,500 to 2,000 years and were found in Argentina.

‘This was possible because skin cells from the scalp become encased in the cement produced by female lice as they attach eggs to the hair,’ researchers explained.

The findings include clues into the migration of pre-Columbian South American people that haven’t been available through other methods.

They believe this method could allow for more unique samples to be studied from human remains – even when no bone or tooth samples are available.

Dr Alejandra Perotti, Associate Professor in Invertebrate Biology at the University of Reading, led the research.

He said: ‘Like the fictional story of mosquitos encased in amber in the film Jurᴀssic Park, carrying the DNA of the dinosaur host, we have shown that our genetic information can be preserved by the sticky substance produced by headlice.’

‘In addition to genetics, lice biology can provide valuable clues about how people lived and ԀiҽԀ thousands of years ago,’ Dr Perotti added.

‘Demand for DNA samples from ancient human remains has grown in recent years as we seek to understand migration and diversity in ancient human populations.

‘Headlice have accompanied humans throughout their entire existence, so this new method could open the door to a goldmine of information about our ancestors while preserving unique specimens.’

Until now, ancient DNA has been extracted from dense bone from the skull or from inside teeth, as these provide the best quality samples.

However, skull and teeth remains are not always available, as it can be unethical or against cultural beliefs to take samples from indigenous early remains.

Severe damage destructive sampling causes to the specimens also make these extractions taboo, as well as compromising future scientific analysis.

‘There is a hunt out for alternative sources of ancient human DNA and nit cement might be one of those alternatives. I believe that future studies are needed before we really unravel this potential.’

As well as the DNA analysis, scientists were also able to draw conclusions about a person and the conditions in which they lived from the position of the nits on their hair and from the length of the cement tubes.

They were able to determine the Sєx of the human hosts, how the populations migrated throughout South America, and evidence of viruses.

The team revealed a genetic link between three of the mummies and other humans are known to be living in Amazonia 2,000 years ago.

‘This shows for the first time that the original population of the San Juan province migrated from the land and rainforests of the Amazon in the North of the continent, in the area south of current Venezuela and Colombia,’ the authors found.

They also discovered that all ancient human remains studied belonged to the founding mitochondrial lineages in South America.

The mummies were all likely exposed to extremely cold temperatures when they ԀiҽԀ, which could have been a factor in their Ԁҽαths.

This was indicated by the very small gap between the nits and scalp on the hairs shaft. Lice rely on the host’s head heat to keep their eggs warm and so lay them closer to the scalp in cold environments.

Shorter cement tubes on the hair correlated with older and less preserved specimens, due to the cement degrading over time.

As well as the University of Reading, researchers from National University of San Juan, Argentina; Bangor University, Wales; the Oxford University Museum of Natural History; and the University of Copenhagen, Denmark were involved.

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