Study finds life relied on rare molybdenum metal 3.4 billion years ago

Wednesday 06 May 2026 - 07:39

Primitive microbes were using molybdenum, a metal that was extremely scarce in the oxygen-poor oceans of early Earth, billions of years before it became widely available, according to a new study published in Nature Communications. The finding challenges a long-standing assumption that life first depended on tungsten before switching to molybdenum, suggesting instead that both metals were central to biochemistry from nearly the very beginning.

The research, led by scientists at the University of Wisconsin–Madison including professor Betül Kaçar, used molecular dating techniques to trace the biological use of molybdenum back 3.3 to 3.7 billion years, well before the Great Oxidation Event approximately 2.45 billion years ago, which eventually brought dissolved molybdenum concentrations in the oceans to their present levels. Geological records show that dissolved molybdenum in Archean oceans was one to two orders of magnitude lower than it is today, making it far from obvious how early organisms could have accessed it in meaningful quantities.

Kaçar explained that the findings point to a more complex early biochemistry than previously modeled. Enzyme systems using both molybdenum and tungsten appear to have Archean origins, indicating that the earliest life forms were likely working with both metals simultaneously rather than transitioning from one to the other in sequence. The study argues that molybdenum use is considerably older than many models had assumed.

Molybdenum plays an essential role in numerous biochemical processes, most notably nitrogen fixation, the conversion of atmospheric nitrogen into forms that living organisms can use. The researchers suggest that hydrothermal systems and localized geochemical conditions may have concentrated the metal sufficiently for early life to exploit it, even when ocean-wide availability was minimal. A 2024 study conducted by the China University of Geosciences had already shown that ancient photosynthetic microbes could extract molybdenum directly from rock minerals, providing a plausible mechanism through which life could have sourced the rare metal in shallow-water environments.

The new study builds on related research published in January 2026 by the same team, which resurrected a 3.2 billion-year-old nitrogenase enzyme and demonstrated that its nitrogen isotope signatures had remained stable across geological time. Together, these findings appear to settle a long-running debate in geobiology: molybdenum was not a late addition to life's chemical toolkit but a founding component of its chemistry. NASA, which funded the research, highlighted the significance of a metal becoming biologically essential despite its scarcity among competing alternatives. The implications extend to astrobiology more broadly. If rarity alone did not prevent molybdenum from becoming indispensable to life on Earth, the assumptions scientists apply when searching for the chemical prerequisites of life on other worlds may need to be revisited.