Oxygen began entering Earth's oceans around 2.32 billion years ago, and shallow seas followed within a few million years.

We think of oxygen as life, sustenance, a literal breath of fresh air. But it's actually a very reactive element. Anyone who's burned a log has witnessed this firsthand. So why do so many life-forms ...

Emma Hammarlund receives funding from the European Research Council Horizon 2020. Imagine a world where the oxygen you need changes dramatically between day and night. Your world shifts from being ...