Freshwater, dry land existed on Earth 4 billion years ago, study finds

A recent study published in Nature Geoscience has revealed that freshwater and dry land existed at the same time on Earth 4 billion years ago, 500 million years earlier than previously thought.

There is a consensus among scientists that these conditions are requisite for life to originate and develop being critical for the formation of amino acids — the building blocks of proteins — and nucleic acids — which store genetic information — into bacterial life.

The oldest proof of life on the planet Earth is detected in rocks dated to 3.5 billion years ago, with some chemical data proposing that the origin of life might be as old as 3.8 billion years.

Dr Hamed Gamaleldien, Assistant Professor, of Earth Science at Khalifa University, along with an international team of researchers studied grains of zircon, a crystal found in Jack Hills, Western Australia, and discovered the earliest record of freshwater found on land.

These crystals, which are highly resistant to weather, were dated and tested for their oxygen isotopic ratios. Some of them presented a light oxygen signature suggestive of freshwater interaction, indicating that freshwater and dry land were present on Earth 4 billion years ago.

These results not only push back the timeline for the potential beginning of life but also offer a clearer picture of Earth's very early environment.

Freshwater and land are indispensable for the complicated evolution of life, providing new insights into those early conditions that might have been instrumental to the origin of life on our planet.