Why does Australia get all the cool fossils and signs of ancient life? It must be the jolly spirit and amazing accents. Scientists have found signs of ancient microbial life in the Dresser Formation, an outcropping of rocks in Western Australia. The newly discovered traces date back almost 3.5 billion years, back to when Earth was in its infancy. Scientists believe Earth is about 4.5 billion years old, but it wasn’t until 100-200 million years later that water-indicating minerals and continents formed. Scientists have long wondered when exactly life started out of that soupy mix, and what it looked like.
A paper published in the journal Astrobiology sheds light on this discovery and its implications. The paper focuses on “microbially-induced sedimentary structures,” (MISS) a phenomenon some scientists believe may be linked to the earliest traces of life. The sedimentary structures form when microorganisms living in microbial mats )(which could be algae, bacteria, fungi, etc.) interact with sediment. There are 17 different types of MISS, which are thought to preserve early life forms better than any other structure. These structures are particularly hardy — despite being formed billions of years ago, they look similar to sedimentary structures that are only hundreds of thousands of years old. Must be the Botox.
Scientists believe that MISS aren’t just discrete examples of life, but rather evidence of ecosystems. In fact, the MISS featured in this study provides evidence of microbes called cyanobacteria, which are the first organisms we know of that were capable of producing oxygen. This means that life was more complex back then than we previously realized, and that life among organisms was a collaborative effort.
The Pilbara region in Western Australia is full of scientific treasure, including stromatolites (fossils created by the layering of sediment and microorganisms) that are roughly 3.45 billion years old and microfossils that are slightly older than that, at 3.47 billion years. Scientists believe that the Dresser Formation is the oldest grouping of sedimentary rocks never to be destroyed or altered by earthquakes or other tectonic plate movement, leaving them as well-preserved as possible. The estimated 3.48-billion-year-old formation unseats a 3.2-billion-year-old South African MISS as the oldest ever discovered.
MISS have piqued NASA’s interest as well, given that these structures, and the microbial mats that helped form them, are one example of life that scientists are trying to find on Mars. MISS may also provide additional information useful in testing the theory that life on Earth actually began on Mars. I personally volunteer to go to Australia to help.