(Love Dalén via SWNS)
By Stephen Beech
DNA dating back over one million years has been identified in the woolly mammoth remains.
Scientists who discovered some of the world’s oldest microbial DNA also identified for the first time bacteria that may have caused disease in the now extinct tusked mammals.
An international team, led by researchers from the Centre for Palaeogenetics in Sweden, analyzed microbial DNA from 483 mammoth specimens, of which 440 were sequenced for the first time.
Among them was a steppe mammoth that lived about 1.1 million years ago.
Using advanced genomic and bioinformatic techniques, the researchers distinguished microbes that once lived alongside the mammoths from those that invaded their remains after death.
Study lead author Dr. Benjamin Guinet, of the Centre for Palaeogenetics, said: “Imagine holding a million-year-old mammoth tooth.
“What if I told you it still carries traces of the ancient microbes that lived together with this mammoth?
“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.”
The team identified six microbial groups consistently associated with mammoth hosts, including relatives of Streptococcus, Actinobacillus, Pasteurella and Erysipelothrix.
(Love Dalén via SWNS)
They said some of the microbes may have been pathogenic. For instance, one Pasteurella-related bacterium identified in the study is closely related to a pathogen that has caused fatal outbreaks in African elephants.
Since African and Asian elephants are the closest living relatives of mammoths, the researchers say that their findings raise questions about whether mammoths may also have been vulnerable to similar infections.
The team reconstructed partial genomes of Erysipelothrix from a 1.1-million-year-old steppe mammoth, representing the oldest known host-associated microbial DNA ever recovered.
They say that pushes the limits of what researchers can learn about the interactions between ancient hosts and their microbiomes.
Study senior author Dr. Tom van der Valk, also of the Centre for Palaeogenetics, said: “As microbes evolve fast, obtaining reliable DNA data across more than a million years was like following a trail that kept rewriting itself.
“Our findings show that ancient remains can preserve biological insights far beyond the host genome, offering us perspectives on how microbes influenced adaptation, disease, and extinction in Pleistocene ecosystems.”
Although the exact impact of the identified microbes on mammoth health is difficult to determine due to DNA degradation and limited comparative data, the researchers say the study provides an “unprecedented” glimpse into the microbiomes of extinct big beasts.
The findings, published in the journal Cell, suggest that some microbial lineages coexisted with mammoths for hundreds of thousands of years, spanning both wide geographic ranges and evolutionary timescales, from over one million years ago to the extinction of woolly mammoths on Wrangel Island about 4,000 years ago.
Ancient DNA expert Love Dalén, Professor of Evolutionary Genomics at the Centre for Palaeogenetics, added: “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,”