To try and comprehend how, when and why life might evolve on other planets, it makes sense to look to the only planet we currently know of which hosts life: Earth. Understanding our own planet’s complicated evolutionary history might provide the key to finding other planets capable of supporting life.
We set out to explore and reconstruct atmospheric oxygen levels during the [Neoproterozoic oxygenation event, or] NOE to see what conditions the first animals appeared under. To do this, we built a computer model of the Earth, incorporating knowledge about the various processes which can deliver oxygen to the atmosphere or remove it.
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Our results suggest that periods of low atmospheric oxygen levels could have been important for developing more complex life by driving the extinction of some simple organisms and allowing the survivors to expand and diversify when oxygen levels rose again. So, we should not rule out taking a closer look at exoplanets that have a poorly oxygenated atmosphere.
Of course, this is a very Earth and even animal-centric view. Alien life may be completely different to life on Earth.
