The curious minds at What If discover what Earth was like 2 billion years ago, exploring early life, atmosphere, and continental formation.

The Purple Earth Hypothesis has significant implications for the search for life on other planets.

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

New research suggests complex life on Earth emerged billions of years before previous estimates. The research also suggests ...

The origins of complex, nucleated cellular life – everything from amoebas to humans – may date back a lot further in Earth's history than we thought. A new study tracing the earliest steps toward ...

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

Parts of ancient Earth may have formed continents and recycled crust through subduction far earlier than previously thought.

Add Yahoo as a preferred source to see more of our stories on Google. Tiny air bubbles trapped in ancient salt crystals are offering the clearest view yet of Earth’s atmosphere a billion years ago.

How did life begin on Earth? While scientists have theories, they don’t yet fully understand the precise chemical steps that led to biology, or when the first primitive life forms appeared. But what ...

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 ...

Deep in some of Earth’s oldest rocks, traces of ancient life still linger, even when every cell has crumbled. You would not see shells, bones, or clear microfossils in these rocks. Instead, you would ...