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Life on Earth appeared 3.75 billion years ago – 300 million years EARLIER than previously thought

Life on Earth appeared 3.75 billion years ago - 300 million years EARLIER than previously thought

Life on Earth first appeared at least 3.75 billion years ago — about 300 million years earlier than previously thought, a new study has revealed.

The revelation is based on analysis of a fist-sized rock from Quebec, Canada, estimated to be between 3.75 and 4.28 billion years old.

Researchers had previously found tiny filaments, knots and tubes in the rock that appeared to be made by bacteria. However, not all scientists agreed that these structures were of biological origin.

Now, after extensive further analysis, the University College London team has discovered a much larger and more complex structure in the rock — a stem with parallel branches on one side that is nearly an inch long.

They also found hundreds of distorted spheres, or “ellipsoids,” next to the tubes and filaments.

The researchers say that while some of the structures may have formed through accidental chemical reactions, the “tree-like” stem with parallel branches was most likely of biological origin.

This is because no structure has been found that is made only through chemistry.

Until now, the earliest known evidence of life on Earth was a 3.46 billion-year-old rock from Western Australia that contained microscopic worm-like fossils.

dr.  Dominic Papineau holds a rock sample estimated to be between 3.75 and 4.28 billion years old

dr. Dominic Papineau holds a rock sample estimated to be between 3.75 and 4.28 billion years old

Life on Earth appeared 3.75 billion years ago - 300 million years EARLIER than previously thought
Life on Earth appeared 3.75 billion years ago - 300 million years EARLIER than previously thought
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Pictured: The ‘tree-like’ stem with parallel branches on one side, considered the most convincing trace of rock life. The main stem starts at the bottom left and extends up almost to the top of the image, with ‘pectinate’ (aligned parallel to one side) branches on the right side of the stem.

How the research was done

Researchers examined rocks from Quebec’s Nuvvuagittuq Supracrustal Belt (NSB), which was once a stretch of seafloor and contains some of the oldest sedimentary rocks known on Earth.

The research team cut the rock into sections as thick as paper (100 microns) using a diamond-encrusted saw to closely observe the tiny fossil-like structures made of hematite, a form of iron oxide or rust. and encased in quartz.

They then compared the structures and compositions to more recent fossils, as well as to iron-oxidizing bacteria found near hydrothermal vent systems today.

This allowed them to identify contemporary equivalents of the spinning filaments, parallel branching structures and distorted spheres (irregular ellipsoids), for example near the Loihi submarine volcano near Hawaii, as well as other ventilation systems in the Arctic and Indian oceans.

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“Using many different lines of evidence, our study strongly suggests that a number of different types of bacteria existed on Earth between 3.75 and 4.28 billion years ago,” said lead author Dr Dominic Papineau of UCL’s Department of Earth Sciences.

This means that life could not have started until 300 million years after the Earth formed. In geological terms, this is fast – about one turn from the sun around the galaxy.”

The team also discovered evidence of how the bacteria got their energy in different ways.

They found mineralized chemical byproducts in the rock that are consistent with ancient microbes that subsisted on iron, sulfur and possibly carbon dioxide and light through a form of photosynthesis without oxygen.

These new findings suggest that a variety of microbial life may have existed on the primordial Earth.

They also affect the possibility of extraterrestrial life.

“If life develops relatively quickly, under the right conditions, it increases the likelihood that life exists on other planets,” says Dr. Papineau.

For the study, the researchers examined rocks from the Nuvvuagittuq Supracrustal Belt (NSB) in Quebec, collected by Dr. Papineau in 2008.

Once a stretch of seafloor, the NSB contains some of the oldest sedimentary rocks known on Earth, believed to be near a system of hydrothermal vents, where cracks in the seafloor allow iron-rich water heated by magma to pass through.

Bright red concretion of hematitic chert (an iron- and silica-rich rock), containing tubular and filamentous microfossils

Bright red concretion of hematitic chert (an iron- and silica-rich rock), containing tubular and filamentous microfossils

Dr Dominic Papineau in his lab at UCL.  The new findings suggest that a variety of microbial life may have existed on the primordial Earth

Dr Dominic Papineau in his lab at UCL. The new findings suggest that a variety of microbial life may have existed on the primordial Earth

The research team cut the rock into sections about as thick as paper (100 microns) to closely observe the tiny fossil-like structures made of hematite, a form of iron oxide or rust, and encased in quartz.

These slices of rock, cut with a diamond-encrusted saw, were more than twice as thick as previous sections the researchers had cut, allowing the team to see larger hematite structures within them.

They compared the structures and compositions to more recent fossils, as well as to iron-oxidizing bacteria found near hydrothermal vent systems today.

This allowed them to identify contemporary equivalents of the spinning filaments, parallel branching structures and distorted spheres (irregular ellipsoids), for example near the Loihi submarine volcano near Hawaii, as well as other ventilation systems in the Arctic and Indian oceans.

For the study, the researchers examined rocks from the Nuvvuagittuq Supracrustal Belt (NSB) in Quebec, collected by Dr.  Papineau in 2008

For the study, the researchers examined rocks from the Nuvvuagittuq Supracrustal Belt (NSB) in Quebec, collected by Dr. Papineau in 2008

In addition to analyzing the rock samples under various optical and Raman microscopes (which measure the scattering of light), the research team also digitally recreated sections of the rock using a supercomputer that processed thousands of images from two high-resolution imaging techniques.

The first technique was micro-CT, or microtomography, which uses X-rays to look at the hematite in the rocks.

The second was a focused ion beam, which skims away tiny – 200 nanometers thick – disks of rock, with an integrated electron microscope creating an image between each disk.

Both techniques produced stacks of images that were used to create 3D models of various targets.

The 3D models allowed the researchers to confirm that the hematite filaments were wavy and twisted and contained organic carbon, characteristics shared with modern iron-eating microbes.

In their analysis, the team concluded that the hematite structures could not have been created by squeezing and heating the rock (metamorphosis) over billions of years.

They pointed out that the structures appeared to be better preserved in finer quartz (less affected by metamorphosis) than in the coarser quartz (which has undergone more metamorphosis).

The researchers also looked at the levels of rare earth elements in the fossil-laden rock and found that they had the same levels as other ancient rock samples.

This confirmed that the seafloor deposits were as old as the surrounding volcanic rocks, and not younger “trickster infiltrations” as some have suggested.

Prior to this discovery, the oldest fossils previously reported were found in Western Australia and dated to 3.46 billion years old, although some scientists have also disputed their status as fossils, arguing that they are non-biological in origin.

HOW IMPORTANT IS PHOSPHORUS FOR LIFE ON EARTH AND HOW DOES IT GET HERE?

While not nearly as abundant on Earth as carbon, hydrogen, or oxygen, phosphorus is one of the most important elements of life on our planet.

It helps form the backbone of the long chains of nucleotides that make up DNA — the building blocks of biological life as we know it.

Phosphorus is also vital for cell membranes and the cell energy-carrying molecule ATP.

Phosphorus probably came to Earth billions of years ago aboard meteorites.

The meteorites are believed to contain a phosphorus-containing mineral called schreibersite.

Scientists recently developed a synthetic version of schreibersite that chemically reacts with organic molecules, demonstrating its potential as a nutrient for life.

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