Scientists have been considering different possibilities to explain the spark that gave rise to life on our planet , such as the impact of lightning or the activity of underwater volcanoes.
However, it is not clear how the first organisms developed in this primitive environment. For example, although life can exist in the absence of oxygen, nitrogen plays a key role in the formation of genes, making it essential for it to thrive.
Now, a team of researchers from the University of Washington has discovered evidence in some of the oldest rocks on Earth that shows that 3.2 billion years ago there were already living things that took advantage of nitrogen in the atmosphere to progress and extend their communities. Until now, this ability was believed to have arisen just 2 billion years ago.
According to Roger Buick, professor of Earth and space sciences at the aforementioned institution, “ in general, there was the idea that there was a kind of nitrogen crisis in the primitive Earth , a phenomenon that made it an inhospitable world, in which it would be difficult to find the conditions for the biosphere to develop.
The ability to fix nitrogen would change everything , so that suddenly, a couple of billion years ago, it became larger and more diverse. Well, our work shows that this was not the case. There was no such nitrogen crisis. The terrestrial biosphere was already remarkable long before it was thought ”.
In a study published in the journal Nature , these experts explain that they analyzed 52 rock samples between 2,750 and 3,200 million years old obtained in South Africa and Australia. In the oldest ones they found the chemical trace that proved that even then there were already organisms capable of taking nitrogen from the atmosphere and that they used it by means of an enzyme based on molybdenum, the most common of the enzymes capable of fixing nitrogen that still exist.
Currently, molybdenum is a fairly abundant element, ending up in the oceans when oxygen reacts with rocks, but its role is unclear billions of years ago, when the atmosphere did not contain enough oxygen. Perhaps, according to the authors of the essay, it was produced in small quantities by the first life forms that settled on earth in single-celled layers.
“We will probably never find direct proof that this was the case, but we do have enough evidence to say that life already existed 3.2 billion years ago . The microbes could have crawled out of the ocean and populated the silt blankets that covered the rocks, ”says Buick.
Photo: R. Buick / UW
