New study traces molybdenum use in life back to 3.3–3.7 billion years ago, before the Great Oxidation Event.
A study published in Nature Communications indicates that life on Earth was utilizing the metal molybdenum as early as 3.3 to 3.7 billion years ago. This period predates the significant increase of molybdenum levels in the oceans, which occurred after the Great Oxidation Event approximately 2.45 billion years ago. The research is the first to trace molybdenum use this far back in time.
Findings
- Molybdenum is a metal essential for enzymes that drive major biochemical reactions in modern organisms, including nitrogen fixation.
- Geological evidence shows only trace amounts of molybdenum were present in Earth's oceans billions of years ago, prior to the rise of oxygenic photosynthesis.
- The study reconstructed the history of molybdenum use along the tree of life and combined this data with information on molybdenum's prevalence through geological time.
- Researchers also examined the use of tungsten, finding evidence that life experimented with both metals billions of years ago.
- The study tracked the movement of molybdenum within cells.
Statements from Researchers
"Both molybdenum and tungsten were used by early life." — Betül Kaçar, professor of bacteriology at the University of Wisconsin–Madison and senior author of the study.
Kaçar stated that molybdenum use dates back to the Eoarchean to Mesoarchean eras (3.7–3.1 billion years ago). She noted that localized systems, such as hydrothermal vents, could have supplied usable molybdenum even when seawater levels were low. Molybdenum's catalytic advantages may have made it worth acquiring despite its scarcity.
Implications
- The finding suggests that life can utilize scarce elements if they provide catalytic advantages.
- For astrobiology, the research indicates that efforts to detect life on other planets should consider different elemental inventories and redox histories.
Funding
The research was supported by NASA and other grants.