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How to analyze stone age DNA

How to analyze stone age DNA

Status: 05/12/2023 06:49 AM

Researchers were able to analyze 20,000-year-old DNA on a necklace without destroying it. Participants speak of a “new era” in DNA research. How does the technology work?

Written by Stefan Troindel and Lena Schmidt, SWR

With the help of a single deer tooth, an international research team has made an archaeological breakthrough: They have developed a new method for extracting DNA and it is now in the specialized journal nature foot. In this way, human DNA could be isolated from the surface of a Stone Age object for the first time without destroying the find.

On April 25, 1953, two researchers wrote a scientific history: Both encode the structure of our genome.

Dentin checked chain necklace

A deer-tooth necklace made between 19,000 and 25,000 years ago has been examined under the Max Planck Institute for Evolutionary Anthropology in Leipzig. The gem was found in the famous Denisova Cave in southern Siberia. The cave is famous for its amazing archaeological finds. For example, the so-called Denisova man, a distant relative of the Neanderthal man, is named after her.

According to the institute, the study promises “A A new era in the study of ancient DNAA Until now, it has not been possible to relate objects from that period directly to the people who made or used them. This is the first time we can establish such a direct link,” explains molecular biologist Elena Essel, who was involved in the research. SWR.

Burials and funerary possessions were scarce at this time, and objects and skeletons were rarely found near each other afterwards. So if a tool is found, it can only be guessed at from the many excavations so far, for example, whether the find was used by “modern” man or Neanderthals. This is a debate that has been going on in archeology for decades, Essel says. The research team now hopes that this method will clarify a large number of results. “That would be crazy,” said the biologist, also V.I SWR.

This was detected through DNA samples

The research group was able to trace a large portion of the DNA on the marker to one person. Based on the number of X chromosomes, they determine that the necklace was made, used, or worn by the woman—whether the artist or the wearer remained open afterwards. However, it is clear that the woman must have used or touched the piece of jewelry extensively over a longer period of time in order for this amount of DNA to be left on it.

Genetic analysis also provided clues to the woman’s lineage. They were closely related to the so-called “Ancient North Eurasian” peoples who lived in the eastern parts of Siberia at the same time.

In addition to female DNA, the genetic material of the animal that supplied the tooth for the piece of jewelry was also extracted. It was an elk deer. This type of deer is still alive today and is found mostly in North America and Northeast Asia.

non-destructive DNA extraction method

Essel explains that bones and teeth have protected DNA from decay for thousands of years. Because the mineral that makes up most bones binds genetic material so well. The researcher says bone tools or artefacts from the Stone Age can still be checked for traces of DNA even after 10,000 years.

Until now, archaeological finds for DNA analysis were often destroyed because they had to be excavated, sawn, or milled. Thanks to the new method, the deer tooth was completely preserved, and further analyzes could be carried out. The team tested the effect of different chemicals on the surface structure of vestigial bone and dental fragments.

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The new, non-destructive method of DNA extraction is based on phosphates and works at temperatures up to 90 degrees Celsius. “I always like to compare it to a washing machine,” says the molecular biologist. The DNA is washed off the found body, so to speak: “We take this stuff and immerse it completely in a buffer that can dissolve the DNA. Then we successively heat that buffer up to 90 degrees and use it to dissolve the DNA from these samples.”

This year’s Nobel Prize in Physiology or Medicine has been awarded to Swede Svante Pääbo, who is researching in Leipzig.

Extreme caution when digging

However, to ensure that the scan is not rigged, great care must also be taken with this procedure. The method only works if archaeologists wear masks and gloves during excavations, for example. Otherwise, the material will be contaminated.

The research team discovered this themselves during preliminary experiments on finds from a French Paleolithic cave. A lot of DNA was also found in these finds – but mainly from those who touched the finds during or after the excavation. Finds from Quinçay Cave date back to the 1970s to 1990s. The analysis of newly discovered artifacts from Siberia has been crowned with success – and may well be a pioneer for the archeology of the future.