The oldest fossils on Earth so far have been uncovered in Western Australia. At around 3.5 billion years old, the tiny fossils serve as the earliest direct evidence of life on Earth.
Thanks to further analysis and study by researchers at UCLA and the University of Wisconsin-Madison, our understanding of life’s origins could become much clearer now, and even pave the way to figuring out how life might exist off Earth.
The study was published on Monday in the Proceedings of the National Academy of Sciences (PNAS).
Critics suggested the fossils, which are invisible to the naked eye, are just unusual shapes in the rock and not evidence of life at all.
Now, work led by Professor William Schopf, the palaeobiologist at UCLA who first described the specimens in 1993, has officially settled the dispute.
The professor described 11 microbial fossil specimens stemming from five different taxa.
They connected the fossil’s morphologies to the chemical signatures we understand to be the basis for life. Some of the microfossil creatures were found to be similar to species alive today.
According to Schopf, through the use of a secondary ion mass spectrometer (SIMS), the team determined the fossils to be “a primitive, but diverse group of organisms.”
The fact that such complexity existed 3.5 billion years ago suggests that the origins of life were actually much earlier, according to the scientists.
Other studies have shown that oceans existed on Earth 800 million years before the creatures in these fossils existed, and this could have facilitated earlier life.
“We have no direct evidence that life existed 4.3 billion years ago but there is no reason why it couldn’t have,” said Professor Valley.
“This is something we all would like to find out.”
“People are really interested in when life on Earth first emerged,” Valley said. “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 analyses will be made on samples of Earth and possibly from other planetary bodies.”