The world’s oldest fossils — smaller than the human eye can see — appear to show life on Earth began in modern-day Australia, scientists have claimed.
The 3.5 billion-year-old microscopic fossils were discovered in the Apex Chert deposit of Western Australia.
Scientists first discovered the tiny fossils in 1982. Eager to analyze them, William Schopf, professor of paleobiology at the University of California, Los Angeles, spent more than 10 years developing a technique to examine the fossils.
Along with a team of researchers, the professor crushed the original rock sample so the delicate fossil inside could be seen.
Critics initially disputed his findings, arguing the rocks were odd-looking minerals.
But today, according to John W. Valley, professor of geoscience at University of Wisconsin-Madison, “I think it’s settled.”
He added: “People are really interested in when life on Earth first emerged. This study was 10 times more time-consuming and more difficult than I first imagined, but it came to fruition because of many dedicated people who have been excited about this since day one.”
“I think a lot more microfossil analyzes will be made on samples of Earth and possibly from other planetary bodies.”
Schopf analyzed the carbon composition of the ancient rock to find out the ratios of different carbon isotopes — that is, different types of carbon.
The scientists discovered the ratios corresponded with the microbe-like structures in the rock.
He believes the fossils reveal life was “already present” 3.5 billion years ago because several different types of microbes were already there.
But, on Earth, because several different types of microbes were shown to be already present by 3.5 billion years ago, Schopf said it tells us that “life had to have begun substantially earlier — nobody knows how much earlier — and confirms it’s not difficult for primitive life to form and to evolve into more advanced microorganisms.”
Valley said: “We have no direct evidence that life existed 4.3 billion years ago, but there is no reason why it couldn’t have.”
“This is something we all would like to find out.”