[Laboratory, Analysis, Chemistry image. Photo Credit to Pixabay]

On September 2nd, 2025, research and details on the discovery of the oldest host-associated microbial DNA was reported in the journal Cell.

Although fossilized traces of bacteria hinted out the past, in order to understand long gone organisms, scientists need their genetic blueprint- DNA.

However, due to its chemical instability and fragility, ancient DNA was not easily found as it could not stand the test of time.

However, modern advancements in sequencing and technology have allowed scientists to push back the boundaries on how much genetic data could be reached.

Researchers at the Centre for Palaeogenetics, a collaboration between Stockholm University and the Swedish Museum of Natural History, analyzed microbial DNA from 483 mammoth specimens, 400 of which were sequenced for the first time.

Utilizing advanced genomic and bioinformatic techniques, researchers successfully distinguished microbes between those which had lived alongside mammoths, and ones which had invaded the bodies after death.

This breakthrough opened a new path in exploring interactions between microbes and lives and deaths of ancient species, especially since knowledge on ancient microbes came from DNA preserved in places.

This included DNA found in permafrost, amber, human remains and artifacts– instead of extinct animals

Scientists had identified 310 microbes connected to mammoth tissues, and had once more analyzed the 1.1 million year old steppe mammoth, which had been found near the Adycha river in northeastern Russia.

The mammoth carried high significance, as scientists had sequenced its DNA in 2021 from its molars, which had been proved to be the oldest DNA discovered at the time.

Once again, researchers had found shocking results, discovering the oldest host-associated microbial DNA recorded from the mammoth.

Not only this, but the team had also successfully reconstructed part of a genome of Erysipelothrix, the microorganism found in the steppe mammoth fossil, amazing several scientists, especially due to the fact that microbial DNA degrades over long periods of time.

This discovery pushed the limits of what could be further learnt about the interactions between ancient species and their microbes.

From the mammoth remains, six different microbial groups consistently associated with mammoth hosts were analyzed, including relatives of Actinobacillus, Pasteurella, Streptococcus, and Erysipelothrix.

It has been found that some of these microbes may have been pathogenic. 

A bacterium related to Pasteurella had been identified to have also caused fatal outbreaks on African elephants in 2020, raising possibilities on how it may have affected mammoths as well due to the close relationships between the two species.

Furthermore, Erysipelothrix was found to be a group of bacteria which could cause endocarditis – a life threatening inflammation of the heart’s interior tissue, usually affecting modern dogs and pigs.

Two groups of Streptococcus were also identified, one of which is a leading cause of tooth cavities in humans due to the strain it could cause.

Although the exact impacts of the identified microbes on mammoth health and well-being have not been determined yet due to DNA degradation and limited comparative data, some predict that mammoths may have been vulnerable to similar infections.

To add on, this data supports the proposal by scientists from 2024, where it had been reported that mammoths were most likely not extinct due to inbreeding, but rather a lucky, random event– such as a virus or natural disaster.

Benjamin Guinet, a key member the research team and the lead author of the study had stated “Our results push the study of microbial DNA back beyond a million years, opening up new possibilities to explore how host-associated microbes evolved in parallel with their hosts,” showing how the research opens a variety of pathways.

This new discovery has completely changed our knowledge, and allowed scientists to study the relationship between ancient animals and microorganisms more deeply.

“This work opens a new chapter in understanding the biology of extinct species. Not only can we study the genomes of mammoths themselves, but we can now begin to explore the microbial communities that lived inside them,” Professor of Evolutionary Genomics at the Centre for Palaeogenetics, Love Dalén, added.

Additional research is required to determine the precise influences of the bacteria on the health of the mammoths.