Don’t hold your breath, but oxygen may not be as essential to biological life as we once thought. A pair of new papers are demonstrating how certain microbes have evolved the ability to suck the energy out of iron, much like we do with oxygen. The tiny creatures have long existed in the cracks of the earth and could shed light on the origins of life on our planet. And maybe other planets, too.

The NASA-funded research exposes the tremendous diversity of life on Earth and raises the possibility that life on other planets may not require oxygen, expanding dramatically the number of locations we have to check. It also harkens back to a time when Earth contained much less oxygen, and iron, still the fourth most common element in the world, would have seemed like a better choice for young organisms. These microbes not only evolved a complex system for harnessing the energy of iron, but they have continued to do so for many millions of years, even after oxygen took over the atmosphere.

“These are fundamental studies, but these chemical transformations are at the heart of all kinds of environmental systems, related to soil, sediment, groundwater and waste water,” senior author Eric Roden, a professor of geoscience at UW–Madison, told Phys-Ed.

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