New Theory Suggests Earth Might Disappear and Reappear Before It Evolves
It has been generally accepted that the complex life of planet Earth has appeared at least 1.27 billion years ago. However, a new research suggests that there may have been a much earlier period where complex life could have evolved before it disappears and the reappears again.
The study, led by the University of Washington and put forward the theory, was published in the journal Proceedings of the National Academy of Sciences. The researchers put into details how the isotopic ration in the element selenium in sedimentary rocks suggests a high presence of oxygen in the atmosphere of the Earth between 2 and 2.4 billion years ago.
IFL Science reported that the suggestion is that, for this relatively brief period in Earth's 4.5-billion-year history, the conditions may have been in favor of complex life. Before, it had been thought that the Earth's oxygen went through a period of none, then some, until to a lot. It is when the eukaryotes -- animals, plants, fungi and protists came into existence.
Thus, the research suggests there was a spike before "none" and that it dropped down again. The study co-author from the University of Washington Roger Buick said that, "There is fossil evidence of complex cells that go back maybe 1.75 billion years. But the oldest fossil is not necessarily the oldest one that ever lived - because the chances of getting preserved as a fossil are pretty low."
In line with this, Buick added that the study revealed there was enough oxygen to allow complex cells to evolve and become ecologically important. However, that does not directly mean that they did.
This is not the first time that the theory of increased oxygen earlier in the Earth's history has been proposed. But, it does provide some additional possibilities, such as Earth's atmosphere and surface ocean experienced an increase of oxygen, but not the deep ocean.
One of the researchers from St. Andrews, University of Scotland, Eva Stüeken, said that, "It's unknown why it happened, and why it ended. That's the million-dollar question," according to Science Alert.