New find could be oldest evidence of life ever discovered ars_ab.settitle(1050961)

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An global team of scientists has discovered what they believe are the fossilised remains of microorganisms that would have clustered around a hot, seafloor vent. Those ancient critters lived an incredible 3.8 to 4.3 billion years ago.

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.

Stromatolites formed in the sunlit surface waters of the sea, and signs of life from hydrothermal vents show that even at this early date life had colonised the sea from its surface to the depths.

A team of experts led by Matthew Dodd of University College London (UCL) searched for signs of the earliest habitable environments on our planet.

Matthew Dodd, a member of the United Kingdom team from University College London (UCL), said: "Our discovery supports the idea that life emerged from hot, sea floor vents shortly after planet Earth formed".

Scientists have found what they claim are the oldest-known fossils on Earth, embedded in Canadian rocks that are at least 3.7 billion years old.

In fact, there's a chance the fossilised microorganisms could date as far back as 4,280 million years ago. However, many scientists believe the Western Australia microfossils are not fossils at all, but the result non-biological processes of geology such as changes in heat and pressure.

Jasper banded iron formation from the Nuvvuagittuq Supracrustal Belt in Québec, Canada, with grey magnetite layers and red haematite-rich silica layer.

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. Furthermore, the 3.7-billion-year-old fossils found in Greenland could have gotten their intriguing chemical signature from a nonbiological process, according to the new study, which was published today (March 1) in the journal Nature.

Some have criticized the findings by pointing out that the rocks appear to to have been volcanically heated more recently, which makes the microfossils dubious.

The researchers expressed confidence the fossils from northeastern Canada were formed by organisms, saying no non-biological explanation was plausible.

He said it wasn't impossible to discover definitive evidence of biological life in these sorts of formation, but it was challenging.

If this is indeed evidence of the earliest known life on Earth, then it suggests the simplest organisms could emerge on a planet nearly immediately, in geological terms. "As organisms die and decay it is released and it can then be incorporated into minerals". Rocks that are three billion years old or older are hard to come by, as they have mostly been crunched up or eroded away many times over through Earth's turbulent history.

Could the bottom of its potential ocean have hydrothermal vents?

Dodd and co-authors found the filaments and tubes inside centimeter-sized structures called concretions or nodules, as well as other tiny spheroidal structures, called rosettes and granules, all of which they think are the products of putrefaction.

As with all such claims about ancient life, the study is contentious.

"All animals when they die, when they are fossilised, they are converted into a mineral mass of apatite and carbonate", Dr Papineau said. Additionally, the Mars rover found complex minerals that were probably created in a relatively habitable environment.

"All these independent lines of evidence tell us that these microfossils are indeed biological in origin", Dodd says.

"We're on a quest to understand our origins and these kind of investigations are fascinating but we have to stay realistic about what we know and don't know", he said.
"The lack of carbon isotopes and graphite compositions prevents further interpretations, such that we can only speculate that they were formed by cyanobacteria".

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