Cement Head Lice Use to Attach Their Eggs Can Preserve Human DNA

Researchers found that human DNA can be extracted from the cement head lice used to attach their eggs to their host's hairs that date back 1,500 to 2,000 years. They discovered that it could provide an important clue to the history of the Americas.

Science Daily reported that the new technique is possible because some skin cells from the scalp are encased in the nit cement that female lice produce as they attach their nits to the hair. Researchers tried it on mummified remains in which its DNA revealed how it died and the possible movements of populations from that period.

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Lice Biology Provides Clues as to How Ancient Humans Died

The study, titled "Ancient Human Genomes and Environmental DNA From the Cement Attaching 2,000-Year-Old Head Lice Nits," published in the journal Molecular Biology and Evolution, reported a new source of high-quality ancient DNA that is a non-destructive sampling method compared to other techniques that harvest the bones or teeth of ancient specimens.

Researchers characterized the host from the cells trapped in the nit cement in which the most well-preserved specimens have nits in their hair, Genetic Engineering and Biotechnology News reported. They noted that finding human DNA in nit cement is like the fictional story of a mosquito encased in amber with dinosaur DNA in the Jurassic Park movies.

Genetic analysis of the encased DNA revealed genetic relationships that suggest that the population of the host migrated from northwest Amazonia to the Andes of central-west Argentina. Further analysis of the mitochondrial DNA of the host lice confirmed this finding.

Moreover, the team investigated the nits on human hair used in textile from Chile and those from a shrunken head of an ancient Jivaroan person from Amazonian Ecuador. The DNA of the head lice mirrors the evolutionary history of the human host, enabling scientists to understand the host's health status to know the specific circumstances present at the time before they died.

They said that the position of the nits, the length of the cement tubes, and their overall biology p[provide clues on the environment of the human host, their health, and the cause of their death. They were able to find signatures of Merkel Cell Polyomavirus, the earliest record of the cancer-producing virus.

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Head Lice May Be a Vector of Merkel Cell Polyomavirus

Merkel cell polyomavirus was first described in 2008 in which scientists found that human skin shed this virus and may cause skin cancer, The Mississippi Link reported. The new study showed that head lice could be a vector for the virus, given the high amounts of DNA they found from the nit cement.

Researchers noted that it was striking how even a tiny amount of DNA could explain how ancient people lived and how ancient lice species were related and give hints of possible viral diseases.

They were also able to know the sex of the human hosts where the lice came from and know that they could be an alternative source of ancient human DNA.