Scientists discovered microbial DNA in woolly and steppe mammoth remains that date back more than one million years. This finding marks some of the oldest host-associated microbial DNA ever sequenced. The research opens new vistas in how microbes may have co-evolved with large mammals and possibly shaped their health, disease, and extinction.
What Was Studied
An international team led by the Centre for Palaeogenetics (Stockholm University & Swedish Museum of Natural History) examined 483 mammoth specimens. Out of those, 440 had never been sequenced before. They covered a broad temporal span: from the Early Pleistocene (about 1.1 million years ago) to the final woolly mammoths on Wrangel Island (~4,000 years ago). The specimens came from multiple regions (Siberia, North America, Britain etc.). The tissues included teeth, skull fragments, and bone.
Key Findings
- The team reconstructed parts of an Erysipelothrix genome from a steppe mammoth that lived ~1.1 million years ago. That represents the oldest example of microbe DNA known to have lived in connection with a host rather than simply in the environment.
- They found six microbial lineages that appeared repeatedly across many mammoth remains. These lineages include relatives of Actinobacillus, Pasteurella, Streptococcus, and Erysipelothrix.
- One Pasteurella-like bacterium is closely similar to a pathogen that causes deadly septicaemia in modern African elephants, suggesting mammoths may have faced related bacterial threats. Erysipelothrix DNA appeared not just in dental material but also in bone, which indicates it may have colonized various tissues.
- Because remains usually accumulate environmental microbes after death, the researchers used genomic and bioinformatic methods to filter out those post-mortem invaders. They thus focused on microbes that likely lived in or on mammoths while the animals were alive.
Why This Matters
- The temporal boundary for how far back host-associated microbial DNA can be recovered has been pushed back substantially. This study shows DNA can survive one million years or more in sufficient condition to identify taxa, lineages, and partial genomes.
- The findings offer deep evolutionary perspective: knowing which microbes remained with mammoths over many generations gives insight into disease pressures, microbiome evolution, and possibly physiological traits that affected resilience or vulnerability.
- This may also inform extinction biology. If pathogens persisted across time and geography, they could have imposed stress on mammoth populations. Of course, climate change, habitat shifts, human hunting etc. also mattered. The microbes are one piece in a larger puzzle.
Limitations & Open Questions
- DNA degradation remains a serious issue: even where DNA survives, it is often fragmented and damaged, which limits reconstruction of full genomes.
- Comparative data is scarce. Ancient microbial reference genomes are few, especially for microbes that depend heavily on hosts. That hampers precise assessments of similarity to modern pathogenic strains.
- We cannot yet determine how pathogenic these microbes were in mammoths. Just because one microbe resembles a modern pathogen does not mean it behaved identically. Factors like immune response, environment, co-infections are unknown.
- Geographic sampling may be biased. Specimens preserving microbial DNA well tend to come from cold climates or permafrost. Mammoth populations in other settings may not preserve DNA so richly.
Did mammoth microbes influence their extinction?
This work breaks new ground. Microbial DNA from mammoth hosts has been retrieved from remains older than one million years. Consistent microbial lineages persisted over vast stretches of time and space. While the exact impact on mammoth health and extinction remains speculative, the study adds a vital dimension: extinct megafauna carried microbial communities that shaped, and were shaped by, their biology.
REFERENCE
Guinet, B. et al. Ancient host-associated microbes obtained from mammoth remains. Cell 186, 1โ15 (2025). https://doi.org/10.1016/j.cell.2025.08.003
