Rock microbes found in WA's Pilbara could be earliest signs of life on Earth

Updated

Researchers say they have potentially discovered the earliest signs of life on Earth in Western Australia's Pilbara, a breakthrough that may help scientists better understand the solar system.

The international team has found evidence of a complex microbial ecosystem in well-preserved sedimentary rocks that are almost three-and-a-half billion years old.

University of Western Australia researcher David Wacey says the microbially-induced sedimentary structures, or MISS, were found in a rock unit called the Dresser Formation, west of Marble Bar.

"They could be the oldest evidence for life on Earth," he said.

"We have found micro-fossils and stromatolites of about the same age, but they are generally a little bit younger, so this could just push back evidence for life on Earth by a few more million years."

A city of microbes communicating with each other

Professor Wacey says the "signs of life are basically degraded parts of microbes that you can no longer see their form".

"You can't see cells any more but what you can see is basically carbonaceous material which are the remnants of these cells," he said.

"And, what's happened is that when they were alive they were interacting with the sediment where they were living and they were creating little communities where they were all kind of helping each other out to survive in what would have been a very harsh environment back then."

He says it gives a new insight into what the microbes were doing.

"To find a whole community of these things and to see that they were interacting with each other and interacting with the sediment they were growing on, you can think of it almost like a microbial city and they're all communicating with each other and stabilising the environment they were living in so they could all survive," he said.

Professor Wacey says the Pilbara is the ideal research base.

"The rocks have been in a very stable environment for an incredibly long amount of time. They're actually probably Earth's oldest, well preserved, sedimentary rocks," he said.

"There are some older rocks on the planet, there's some in Greenland but they've been deformed more so it's very hard to see what the original structure of the rock was, whereas these have had very little deformation to them and they essentially look pretty much like they would have done billions of years ago."

The microbial structures are among the targets of Mars rovers which search for similar biological signals on the planet's surface.

Mars rovers searching for similar microbes

Professor Wacey says the team's findings could be significant for space research.

"You've got rovers up there now, searching for signs that Mars was once habitable," he said.

"If they were found on a very primitive Earth then those sort of environments could be very similar to the environments on Mars now, so that's one of their bits of significance.

"I mean going further forward you're looking at possibly collecting samples from Mars and bringing them back to Earth and we could study those in a similar way to the way we have studied the samples in the Pilbara."

Topics: science-and-technology, earth-sciences, astronomy-space, the-universe, marble-bar-6760, wa, australia

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