The first identifiable metabolism
Sulfur isotopes in Australian barite reveal microbes making a living the same way their descendants still do.
- When
- Known to
- ± 30 million years
- Era
- Paleoarchean, Archean
Microscopic pyrite crystals in the 3.47-billion-year-old North Pole barite deposit show a spread of sulfur-34 values that only microbial sulfate reduction produces. It is the earliest evidence not merely that life existed but of what it was doing — a specific biochemical pathway, still used by anaerobic bacteria today, identified in the rock record.