'Great oxidation event' completely changed the Earth

Earth has no oxygen 2.4 billion years ago. Experiencing a leap of evolution, when oxygen appeared, the planet's ecosystem changed completely.

The leap completely changed the Earth

According to the BBC, scientists call it the " great oxidation event" - creating oxygen on a global scale. Without it, there will be no oxygen respiration species that exist and the organisms will not be able to diversify from low-level single-celled to higher-grade multicellular flora and fauna, including humans.

Earth before oxygen.(Photo: SPL)

For many years, scientists believe that the very first life forms created "great oxidation events". And to do this, they themselves must go through a leap forward.

The Earth formed about 4.5 billion years ago. At the time of the " great oxidation event ", the entire Earth had only unicellular organisms . According to fossil evidence, the first unicellular organism appeared on Earth 3.5 billion years ago, before " a great oxidation event " about a billion years ago.

The group of organisms thought to produce oxygen for the Earth is cyanobacteria. The ancestor of this algae at 2.4 billion years ago was the first photosynthetic species (producing sugar through sunlight, CO2 and water).Oxygen is an excess product of this process, which is released into the atmosphere. The mechanism of oxygen occurrence has been explained, but scientists have yet to explain why the algae need so long (nearly a billion years) to start "the great oxidation event." ".

The current blue-green algae, which often form blue scum on the water surface.(Photo: NPL)

To answer this question, Dr. Bettina Schirrmeister, of Bristol University, UK, conducted research on 756 genes of the current blue-green algae. She concluded that cyanobacteria have evolved from single-celled multicellular organisms, just before the " great oxidation event ." Even cyanobacteria began to evolve to obtain cells. loss of ability to divide, but specialized by function, this is considered the first "version " of specialized cells that animals today have, like muscle cells, nerves or blood cells.

These are the factors that help Cyanophyta gain the advantage of survival at that time, and begin photosynthesis to release oxygen into the atmosphere as well as more easily stick to the rock due to the large surface area, difficult to flow. water swept along, thus proliferating more easily than unicellular organisms. Also when needed, populations of blue algae can also move from one place to another. This is very important in the early Earth, when there is no ozone layer to prevent harmful solar radiation .

This hypothesis of Dr. Schirrmeister still needs to be verified, by cultivating cyanobacteria in conditions simulated by Earth 2.4 billion years ago, whether it is true that they produce oxygen on the scale global or not.

In addition, scientists are still investigating if true evolution into multicellular organisms gives Cyanobacteria many survival advantages, why they need to take a billion years to do this. Dr. Schirrmeister said that it may be because this evolutionary process requires too many new genes to appear.

" The next step is to find out which genes are responsible for evolving cyanobacteria into multicellular organisms ," Schirrmeister said. " At that time, I was able to explain why the evolution process took so long. " Whatever makes "great oxidation events ", it is clear that it is one of the most important things. The most happening to this planet.