Scientists Investigate the Bacteria That Colonized Extinct Mammoths—and Uncover the Oldest Known Microbial DNA From a Host

Some of the microbes might have been benign or helpful, while others could have caused deadly diseases

Sarah Kuta | Daily Correspondent

September 8, 2025

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Just like humans, mammoths had a robust community of microorganisms living on their skin and inside their bodies.

Now, for the first time, scientists have identified some of the individual species that made up the microbiomes of these extinct mammals. The findings, published September 2 in the journal Cell, could one day lead to insights into how microbes helped or hurt the hulking creatures—including whether they played a role in the eventual demise of mammoths.

“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,” says study co-author Tom van der Valk, a researcher at the Center for Paleogenetics in Sweden, in a statement.

Researchers took samples from the teeth, tusks, bones or skin of 483 mammoths. The specimens came from all over the world and spanned a wide time frame, including some from Wrangel Island, which hosted the last surviving population of woolly mammoths before they went extinct roughly 4,000 years ago.

The oldest creature in the study was a 1.1-million-year-old steppe mammoth (Mammuthus trogontherii) found near the Adycha River in northeastern Russia. In 2021, that same mammoth made headlines when scientists sequenced DNA from one of its molars.

For the new study, scientists not only sequenced the DNA of the various mammoths—including 440 that had never been sequenced or published before—but they also identified DNA from 310 different microbes living on or in the animals’ tissues. Many of those microorganisms probably showed up after the mammoths died. But the scientists also identified six “host-associated” microbial groups that likely colonized the mammoths when they were still alive.

The researchers can’t say for certain, but the mammoths might have gotten sick from some of those microorganisms. One was Pasteurella, which was similar to a strain of bacteria that killed six African elephants, among the closest living relatives of mammoths, in Zimbabwe in 2020. Another was Erysipelothrix, a group of bacteria that can cause endocarditis, a life-threatening inflammation of the heart’s interior tissues, in modern dogs and pigs. They also found two groups of Streptococcus, including one that’s related to a strain that leads to tooth cavities in humans.

Because they found partial genomes of Erysipelothrix in the remains of the 1.1-million-year-old steppe mammoth, it’s now the oldest known host-associated microbial DNA ever sequenced.

“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,” lead author Benjamin Guinet, an evolutionary biologist at the Center for Paleogenetics, says in the statement.

Scientists will need to conduct additional research to determine how these bacteria might have affected the health and well-being of their mammoth hosts. Some might have been benign or even helpful, while others might have caused deadly diseases. But for now, the study is a “good proof of concept” that ancient bacteria can be identified based on their DNA, says Eva-Maria Geigl, a paleogeneticist at the Institut Jacques Monod in France who was not involved with the research, to Nature’s Katie Kavanagh.

Nicolás Rascován, a geneticist at the Pasteur Institute in France who was not involved with the research but did help peer-review the paper, echoes that sentiment, adding that the research “opens the door to exploring the microbiota of extinct species and asking ourselves what their microbial ecology was like,” he tells El País’ Nuño Domínguez.

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Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.