It seems life on Earth began earlier than initially thought. Scientists have recently discovered that the primordial phase began 3 billion years ago.
The Earth environment was initially unfriendly, with an atmosphere that lacked oxygen and an erratic climate. Still, life started to flourish.
A new study that was published in the Nature journal analyzed 52 samples coming from some of the oldest rocks on Earth. The samples have an age ranging between 2.8 and 3.2 billion years.
The team of scientists found the samples had organisms with the ability of extracting nitrogen from the atmosphere and turning it into a usable form. These organisms had first appeared 3.2 billion years ago. Previous estimates indicated they would have appeared only 2.2 billion years ago.
So primordial life forms might have survived without the need of oxygen, which wasn’t available on Earth until a phase called “the great oxygenation event” which took place 2.3 billion years ago. Instead of oxygen, these apparently used nitrogen to build genes and generate other important life processes.
This type of nitrogen, however, existed in the atmosphere only under a bonded form, which could not be used in the chemical reactions. Scientists believe that natural phenomenon such as lightning may have contributed to the splitting of some bonded forms, resulting in small amounts of free nitrogen.
As there were only small quantities of nitrogen available, organisms needed a way to produce its own – through an enzyme that could extract bonded forms from the atmosphere and convert it into a usable form. Evidence for the existence of such an enzyme was found in the rock samples. The team identified a chemical characteristic to the nitrogen-fixing process.
Study co-author and professor at the University of Washington Roger Buick explained the importance of their findings:
“Our work shows that there was no nitrogen crisis on the early Earth, and therefore it could have supported a fairly large and diverse biosphere.”
Lead author Eva Stueken, also a University of Washington professor stated that their findings indicate that intricate biological processes might have developed easier than initially thought. She added that “Imagining that this really complicated process is so old, and has operated in the same way for 3.2 billion years, I think is fascinating.”
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