Scientists Think They've Found the Oldest Fossil Ever
Mar 02 2017
They are represented by tiny filaments, knobs and tubes in Canadian rocks dated to be up to 4.28 billion years old.
The bugs, which lived on iron, are believed to have thrived in a deep sea hydrothermal vent system, a region of volcanic activity on the ocean floor.
If these fossils are really ancient bacteria, it means that life arose and evolved quickly on Earth, and there's no reason to believe it might not do the same on other planets under similar conditions.
She also said the maximum age of the rocks had proven to be very controversial, and that the true age was more likely to be closer to the 3.77-billion-year age.
Before this find, the earliest accepted evidence for life were 3.7-billion-year-old stromatolite fossils from the Isua Greenstone Belt in south-west Greenland. This is some of the earliest sedimentary rock yet discovered on Earth.
"These rocks have been cooked, they've been squeezed, they've been cooled down, then cooked and squeezed again". The structures appear to be the oldest known fossils, although some scientists are skeptical of the findings. Hydrothermal vents deep beneath the oceans have always been thought to be where life originated, leading Matthew Dodd and colleagues to search where they did. The remains could even be as old as 4,280 million years.
The paper's evidence that the rock features were caused by living organisms falls short, he said. Such filaments and tubes have also been seen in much younger "microfossils", named due to their microscopic size, found in Norwegian rocks. Though the data are less definitive than the evidence for life in younger rocks, he says, this "may be as good as it gets for as old as these rocks are".
"It provides us with this high degree of certainty that these structures are indeed, biological microorganisms that were living and thriving around hydrothermal vents billions of years ago", he says. "The individual lines of chemical evidence are not particularly strong, but put these together with the evidence from the filaments and one comes up with a pretty convincing biological scenario", he says. "We already have evidence of water at the surface of the Earth by about 4.3 billion years ago".
"All animals when they die, when they are fossilised, they are converted into a mineral mass of apatite and carbonate", Dr Papineau said. This also shows that hydrothermal vent environments were also one of the first, if not the first, places occupied by life on Earth. "You do get unique structures in these mat communities that are very easily identifiable as biological", he says.
"It's very possible that there was life at that time - I think it's nearly certainly the case - but as we delve deeper in the rock record, each interpretation gets more contentious, but here I think the science doesn't hold", said Professor Van Kranendonk.
"When I saw these structures in the field, I said, 'I have to sample this, '" Papineau said. "The lack of carbon isotopes and graphite compositions prevents further interpretations, such that we can only speculate that they were formed by cyanobacteria".