Oxygen in the Earth's atmosphere, which paved the way for intelligent life, evolved "spontaneously" rather than as a result of major biological or tectonic shifts
The three jumps in oxygen levels in the Earth's atmosphere occurred spontaneously, and not as a result of biological or tectonic revolutions, the study says.
Approximately 2.4 billion years ago, the Earth's atmosphere did not contain oxygen, and at this moment the first of three so-called "major oxygenation events" occurred.
The great oxygenation event was followed by two more dramatic increases in oxygen content, one about 800 million years ago and the other 450 million years ago.
Scientists believed that each of these events must have had a specific source - for example, tectonic activity, causing shaking the earth's crust and volcanoes.
However, experts from the University of Leeds believe that each event was an inevitable result of feedback processes in the cycles of oxygen, carbon and phosphorus.
All that was required, they argue, was the initial start of plate tectonics and the evolution of early photosynthetic, oxygen-producing microbes.
Thus, it would simply be a matter of time before atmospheric oxygen reached the levels needed to sustain complex life.
Our work shows that the relationship between the global cycles of phosphorus, carbon and oxygen is fundamental to understanding the history of the Earth's oxygenation.
It could help us better understand how a planet other than ours could become habitable, scientists say.
