Ancient microorganisms flourished on land long before we thought

The origins of life on Earth remain a huge scientific mystery. We know life started simple and small, but just where and under what circumstances did that first spark appear?

Charles Darwin's best guess was that life started in freshwater pools on land on a primeval Earth. 

But over the years, scientists have suggested a more likely scenario was that life started deep in the oceans, around rich, hot hydrothermal vents, like the bubbling "black smokers."

The ocean theory has been supported by good evidence, like fossils found recently in northern Quebec that could be over four billion years old.

• Oldest traces of life on Earth found in Quebec, dating back roughly 3.8 billion years

• Tetrapod Fossils Fill in the Blank

• Quirks & Questions: How can I guarantee I'll become a fossil after I die?

Now, new evidence found in remote Western Australia could be tilting the scales back to Darwin's freshwater springs on land idea. These rocks may also have implications for the search for life on Mars.

Joining Quirks & Quarks to tell us more is Tara Djokic, a PhD candidate in geoscience at the University of New South Wales, Australia.

• Paper in Nature Communications: Earliest signs of life on land preserved in ca. 3.5 Ga hot spring deposits