Microbial life in Earth's deep biosphere survives mountain-building and erosion for hundreds of millions of years

A new study published in *Communications Earth & Environment* shows that microbial communities deep beneath the Earth's surface have survived and repeatedly thrived through hundreds of millions of years of mountain‑building and erosion. By examining minerals, fluids and gases extracted from a 2.3‑kilometre‑deep borehole in central Sweden, scientists have traced the history of life that has persisted in the planet’s deep subsurface.

The researchers identified episodic bursts of methane‑producing bacteria that correlate with major geological events that shaped Scandinavia. The data indicate that these microbes were able to exploit transient energy sources generated during tectonic uplift and subsequent erosion, allowing them to rebound and expand whenever conditions became favourable. The study provides a detailed record of how deep‑seated life responds to long‑term geological change.

These findings underscore the resilience of subsurface ecosystems and suggest that life can remain viable in extreme, isolated environments for geological time scales. The work also offers new insights into the biogeochemical cycles of methane and the potential for life in analogous habitats beyond Earth.