In a discovery that could influence the search for life on other planets, an international team of researchers working in Western Australia's Pilbara region have uncovered evidence of complex microbial ecosystems dating back 3.5 billion years. That's 300 million years earlier than previous finds.
What the researchers discovered was a particularly ancient geological phenomenon called microbially induced sedimentary structures, or MISS. These structures were created by "microbial mats" — highly diverse microscopic communities of bacteria that responded to changes in physical sediment dynamics. These layers are frequently found in a wide variety of environments, including tidal flats, lagoons, riverine shores, and lakes. MISS become the final resting place for these microbial mats, which then become a fixture of the geological record, the oldest of which date back 3.2 billion years.
Well, that was before this latest discovery. The researchers, a team that included University of Western Australia Research Assistant Professor David Wacey, found the well-preserved primordial ecosystem in a 3.5 billion-year-old sedimentary rock sequence dating back to the Archean Era.
The Pilbara region is proving to be a remarkable place that's providing important insights into the early evolution of life on Earth.
The Archean was a period during Earth's early history when the atmosphere lacked free oxygen. Fossils of cyanobacterial mats show that stromatolites were instrumental in producing the oxygen required for more complex life. Indeed, life was present during this era, but was limited to simple non-nucleated single-celled organisms called prokaryotes.
Multicellular animal life emerged on Earth about 555-million-years-ago, but MISS provides geological evidence of complex and rich microbial ecosystems before multicellular creatures were common.
Indeed, the significance of MISS is that they demonstrate the presence of whole microbial ecosystems that could coordinate with one another to respond to changes in the environment. This latest study, which was published in the journal Astrobiology, could be significant for studies of life elsewhere in our solar system and beyond. And in fact, MISS are often the targets of Mars rovers, which search for similar biological signatures on that planet's surface.
Read the entire study at Astrobiology: "Microbially Induced Sedimentary Structures Recording an Ancient Ecosystem in the ca. 3.48 Billion-Year-Old Dresser Formation, Pilbara, Western Australia."
Top image: Image Wizard/Shutterstock. Inset image: Astrobiology/Noffke et al.