Nobody knows how life began on Earth, but some tantalizing clues from an asteroid suggest it might not have started here.

The way amino acids are synthesized has changed during the history of Earth. The Hadean eon represents the time from which Earth first formed. The subsequent Archean eon (approximately 3,500 ...

The Precambrian eon is vast, almost unimaginably so ... this includes all of geological time prior to the Cambrian period. Hadean Era (4,550-3,850 mya) The Precambrian's oldest era, the Hadean ...