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Oldest Evidence Of Life On Land Found In Australian Outback

The 3.48 billion-year-old fossils suggest life existed on land earlier than we thought.

10/05/2017 2:40 PM AEST | Updated 10/05/2017 2:40 PM AEST
Kathy Campbell / UNSW
Tara Djokic and Professor Martin Van Kranendonk found the fossils in the Dresser Formation in the Pilbara in Western Australia.

The oldest evidence of life on land has been discovered in rocks in the Australian outback, in findings that could have big implications for the origins of life on Earth and even the quest to find life on Mars.

Australian researchers found the 3.48 billion-year-old fossils in hot spring deposits in the Pilbara -- an isolated outback region of Western Australia -- which are the oldest evidence of life ever discovered on land.

Before this, the oldest evidence came from deposits found in ancient soils in South Africa, which are dated at between 2.7 and 2.9 billion years old.

Life was inhabiting the land much earlier than previously thought, by up to about 580 million years."

While these single-celled organisms are a long way from the intelligent lifeforms that wander the planet today, the find suggests life was able to exist on land at a time when the oceans regularly reached boiling point and not long after the 'late heavy bombardment' period, when asteroids regularly peppered the planet.

These 3.48 billion-year-old life forms would be 14 times older than dinosaurs -- who roamed the Earth just 240 million years ago -- and not too much younger than the Earth itself, which is around 4.5 billion years old.

It's also worth keeping in mind that without microbes, we couldn't digest food, plants couldn't grow and there would be a whole lot less oxygen for us to breath.

"Our exciting findings don't just extend back the record of life living in hot springs by 3 billion years," explained the first author of the study, UNSW PhD candidate Tara Djokic.

"They indicate that life was inhabiting the land much earlier than previously thought, by up to about 580 million years."

The new findings were published in the scientific journal Nature Communications on Tuesday.

UNSW
Spherical bubbles preserved in the rocks suggest microbes lived there.

There are two competing theories on how life on Earth began. The first, dominant theory is that it started deep under the ocean with simple metabolic reactions in hydrothermal vents. The second is that it begun on land in what Charles Darwin famously described as a "warm little pond".

These ancient finds in Western Australia lend weight to a land-base origin of life like what Darwin described back in 1871, says Djokic.

The oldest evidence of life on Earth -- 3.7 billion-year-old fossil stromatolites in Greenland -- are believed to have developed in a shallow sea.

The research also has implications for the search for life on Mars, the scientists say, as the red planet has ancient hot spring deposits of a similar age to the Dresser Formation in the Pilbara.

"The Pilbara deposits are the same age as much of the crust of Mars, which makes hot spring deposits on the red planet an exciting target for our quest to find fossilised life there," says Professor Van Kranendonk.

University of Auckland / Kathleen Campbell
Ridges in the Dresser Formation in the Pilbara preserve ancient stromatolites and hot spring deposits.

Kranendonk worked on the study and is also the Director of the Australian Centre for Astrobiology and head of the UNSW school of Biological, Earth and Environmental Sciences.

He has also given geological advice to NASA on where to land the rover on the 2020 Mars Exploration Mission.

In 2020, NASA is preparing a Mars landing. One of the top three potential landing sites, Columbia Hills, is believed to be a hot spring environment.

"If life can be preserved in hot springs so far back in Earth's history, then there is a good chance it could be preserved in Martian hot springs too," Djokic said.

The researchers are attempting to get World Heritage listing for the major fossil sites in the Pilbara to ensure they remain preserved.


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