(ORDO NEWS) — Iron is an essential component of proteins and enzymes necessary for life. This element is, in principle, needed for its inception. Therefore, too little of it makes the planet not very habitable. But an excess of iron, as on Mars, is bad: it will interfere with the retention of liquid water on the surface.
It is believed that on the young Earth, the iron content was optimal in order to keep water in a liquid state and at the same time dissolve in it. The latter circumstance made iron available for feeding simple forms of life. But 2.45 billion years ago, the planet’s oxygen levels began to rise – a process called the oxygen catastrophe.
As a result, free oxygen appeared in the Earth’s atmosphere, and the general nature of the “air” shell of the planet changed from reducing to oxidizing. The original atmosphere is believed to have been based on carbon dioxide, hydrogen sulfide, ammonia and methane. The cause of the oxygen revolution, most likely, was primarily cyanobacteria , in which oxygen photosynthesis arose 2.7-2.8 billion years ago.
An increase in the amount of O2 in the atmosphere caused it to react with iron. This led to the fact that it stopped dissolving in water. Thus, life had to find new ways to obtain iron. And one of them, according to researchers from the universities of Oxford (UK) and Lorraine (France), was the development of multicellular life – in order to more efficiently absorb this element. The work of scientists is published in the journal PNAS .
The need for iron as the driving force behind the evolution and subsequent development of a complex organism can be a rare or random occurrence, which is important for assessing how common complex life forms are on other planets. And such things have yet to be explored. Nonetheless, the researchers say that now knowledge of the importance of iron for the development of life may help in the search for planets on which such biological processes could take place.
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