Life on Earth began 260 million years after the planet’s early atmosphere witnessed two major spikes in oxygen concentration — the first one is called the ‘great oxygenation event,’ which occurred one roughly 2.3 billion years ago, and a second occurred 800 million years ago. Researchers say that fluctuations in oxygen levels, falling to from 0.1% to rising as high as 40% of present atmospheric levels is the probable cause for the evolutionary silence dubbed the “boring billion.”
Read more in Nature.
doi:10.1038/nature.2014.15529
