In 2024, scientists studied a 52,000-year-old mammoth, and found something ancient DNA was never expected to keep

Even nowadays, any researcher studying ancient DNA is working exclusively with fragments. First, researchers extract DNA fragments from bones, teeth, or preserved samples of an organism, and further, applying various methodologies, they attempt to reconstruct the genome of the species step-by-step. Such discoveries have significantly impacted the views regarding mammoths, Neanderthals, and a number of other extinct organisms.

Nevertheless, there is always one limitation. Given that DNA starts decaying over time, much of it cannot be researched anymore since it has disintegrated. Such considerations guided many scientific efforts in this sphere for decades. At least until scientists decided to conduct research on a woolly mammoth found in Siberia. At first, it seemed to be just another promising sample which can be studied. The results were unexpected.

Why the mammoth was unique


First of all, the discovered mammoth was female, and she lived around 52,000 years ago. Another thing which distinguished her was the excellent state of preservation of her skin. As stated in the scientific article published in the journal Cell in 2024, the significance of the findings could be understood only afterward via the application of novel imaging and genomics techniques.

In addition to detecting fragments of DNA, it became apparent that the structure of chromosomes of the ancient animal had also been preserved.

Chromosomes are not simply strands of DNA but much more intricate three-dimensional formations. In all cells, DNA is organized in such intricate three-dimensional formations that facilitate gene expression regulation. Scientists supposed that although fragments of DNA could be kept for thousands of years, three-dimensional structures would not survive. However, it appears that this assumption was wrong as at least partial preservation was discovered.

PaleoHiC technology helped scientists identify characteristics of the genome architecture of the ancient animal, specifically chromosome territories, loops, compartments, and formation associated with inactive X chromosome.

According to Nature magazine, the discovery is the first identification of fossil chromosomes in frozen mammoth skin. This helps us know what more could be found in the relics of olden times, say the scientists in their article that appeared in Nature magazine.

How freeze-drying helped in preserving the chromosomes

The scientists have based their discoveries upon the following exceptional natural process. According to the study results, it seems to be that the tissue had been subjected to natural freeze-drying because of extremely cold and dry environment, which resulted in complete drying of the water inside the cell, but did not disrupt its internal structure. This means that such circumstances helped create some sort of glass inside the tissues, thereby helping the chromosomes retain their shape.

In order to confirm their hypothesis, scientists made a comparison between the samples of mammoth tissue and those tissues which underwent artificial freeze-drying process. Similar effects of preservation were discovered; hence, it may be concluded that preservation was the result of some natural conditions.

What makes this research special compared to regular ancient DNA studies

Typically, such research projects aim at extracting genetic sequences. This has led to significant findings such as DNA sequences from a one-million-year-old mammoth featured in a historic study published in Nature in 2021. The latest mammoth research takes things one step further.

Rather than focusing only on analyzing the genetic codes, the researchers have been able to examine how the genetic information was organized within the cells. The preserved structures can reveal more about gene regulation and organization in ways DNA sequences alone could never reveal. A feature in Nature Genetics pointed out that the mammoth had preserved features like domains, loops, and chromosomes territories, which are often seen when studying modern chromosomes.

What it means for future fossils

Scientists have been cautious not to overstate the discovery. The study only included a single sample and an exceptionally well-preserved one at that. Fossil chromosomes may prove uncommon for ancient species. However, this research broadens scientists' horizons.

One of the co-senior authors Dr. Erez Lieberman Aiden explained that the mammoth had preserved a snap of the genome structure that had not previously been believed possible to retrieve from such old samples.

In summary, one thing that becomes obvious is that some fossils could potentially yield even more data than originally thought possible. Paleogenetics has mostly involved the analysis of DNA sequencing in extinct organisms. The case of the mammoth shows that sometimes it might be even possible to retrieve the original structure of the genome too.

It seems that future studies will need to involve the examination of not only what DNA survived in extinct creatures but also how was it structured back in the day. The discovery that a Siberian mammoth preserved in a frozen state revealed the actual structure of its genome is a very significant milestone for paleogenetic research. It opens a whole new field of paleogenetics which has not been researched before.