Oxygen is everywhere on Earth today. But that hasn’t always been the case. Scientists think oxygen only became a lasting part ...

Aerobic respiration began hundreds of millions of years earlier than previously thought, a new study suggests.

Oxygen fills the air today, but for most of Earth’s early history it barely existed. Scientists say the atmosphere did not hold steady oxygen until about 2.33 billion years ago, during the Great ...

Oxygen is a vital and constant presence on Earth today. But that hasn't always been the case. It wasn't until around 2.3 billion years ago that oxygen ...