Paleobiologists have confirmed today that life forms existed some 3.5 billion years ago. The new study, published in the journal Proceedings of the National Academy of Sciences, uses the latest techniques to date the most aged remains available. Quartz reports: The research, led by paleobiologist William Schopf of the University of California-Los Angeles and geoscientist John Valley of the University of Wisconsin-Madison, has been in the works for what seems a long time to most, but which the academics know is merely a blink of the eye in terms of life on Earth. The specimens in question, mostly now-extinct bacteria and microbes, were found in 1982 at the Apex Chert, a rock formation in Western Australia, in a piece of rock. In 1993, based on radiometric analyses of the rock, and the shape of fossils, Schopf dated them as biological beings that existed 3.45 billion years ago. The rock held the earliest direct evidence of life, Schopf thought, and inferred from it that creatures existed over a billion years earlier than anyone previously believed. But some scientists argued that this claim was too speculative and that the microfossils, invisible to the naked eye, were really just weirdly-shaped bits of rock, strange minerals that only seem to contain biological specimens but do not.
Since then, technology has improved and Schopf and Valley teamed up to devise a new way to analyze the rock specimen, which now lives in the London Museum of Natural History. Valley spent 10 years developing a method to analyze the individual species that are shaped like tiny cylinders and filaments. Any type of organic substance (including both rock and microbe) contains a characteristic mix of carbon isotopes. Using a secondary ion mass spectrometer (a very rare tool, one of which is housed at the University of Wisconsin), the scientists were able to separate the carbon in each fossil into isotopes. That way, they could measure the carbon-isotope makeup of each fossil, and compare those to fossil-less rocks from the same era. […] After analyzing the microfossils individually, they identified five species, concluding that two were photosynthesizers, two were methane-consuming organisms, and one produced methane.
Read more of this story at Slashdot.