World's "oldest fossils" found in Western Australia dating back 3.4 bn years

Australian and British scientists say they have found the world's oldest fossils, microbes dating back 3.4 billion years, in outback Australia.</p>

Australian and British scientists say they have found the world's oldest fossils, microbes dating back 3.4 billion years, in outback Australia.

Everyone knows Australians love nothing more than to sun themselves on the beach. What nobody knew until recently is that they've been doing it for 3.4 billion years.

Scientists from Australia and Britain say they have found the oldest fossils on earth, tiny single-cell organisms that lived in rocks on the shores of a sulfurous sea 3.4 billion years ago.

David Wacey of the University of Western Australia and Martin D. Brasier of the University of Oxford described their discovery in Sunday’s issue of Nature Geoscience, according to The New York Times.

The bacteria-like creatures, possibly the oldest living things known to science, were found in sandstone at the bottom of the Strelley Pool rock formation in Western Australia.

The world back then was an unfamiliar and extremely inhospitable place, the Times reported:

The sandstone, 3.4 billion years ago, was a beach on one of the few islands that had started to appear above the ocean’s surface. Conditions were very different from those of today. The moon orbited far closer to earth, raising huge tides. The atmosphere was full of methane, since plants had not yet evolved to provide oxygen, and greenhouse warming from the methane had heated the oceans to the temperature of a hot bath.

Microfossils, or imprints of single-cell animals, are notoriously difficult to discern from mineral impressions in rocks, leading to much debate and controversy in the scientific world.

But Wacey and Brasier used smart new technology to analyze the composition of material within the fossil cell walls, and found carbon, sulfur, nitrogen and phosphorus. Carbon and nitrogen are common to all life forms.

In the absence of oxygen, the microfossils are believed to have fed off sulfur compounds, the study says.

"To us it would have seemed like a hellish place to live," Professor Brasier was quoted as saying by the Guardian. "To early life, this was paradise. A true Eden."

Wacey added:

What we can say is that early life was very simple, just single cells and small chains, some perhaps housed in protective tubes. The new evidence from our research points to earliest life being sulfur-based, living off and metabolising compounds containing sulfur rather than oxygen for energy and growth.

The New York Times said Wacey and Brasier agreed to remove a reference in the study to the microfossils being the oldest ever found, due to the sensitivity of such claims. Another team of scientists believe they've found 3.5-billion-year-old microfossils, also in Western Australia, but this research is controversial.

OK, so some scientists found the footprints of a few really old bugs. So what?

Wacey said it was important to understand how life evolved on earth so that we can know what to look for as we explore other planets.

"It is vital to know what the most simple life on our planet looked like, and how to unambiguously identify it, if we are to have any chance of identifying life elsewhere," he told the Guardian.