The Archaea evolved as one of the three primary lineages several billion years ago, but the first archaea to be discovered were described in the scientific literature about 130 years ago. Moreover, the Archaea were formally proposed as the third domain of life only 20 years ago.

When did archaea originate?

Archaea and Evolution

Archaeans are an ancient form of life, possibly the most ancient. Putative fossils of archaean cells in stromatolites have been dated to almost 3.5 billion years ago, and the remains of lipids that may be either archaean or eukaryotic have been detected in shales dating from 2.7 billion years ago.

How was the first archaea discovered?

The first observed archaea were extremophiles, living in extreme environments such as hot springs and salt lakes with no other organisms. Improved molecular detection tools led to the discovery of archaea in almost every habitat, including soil, oceans, and marshlands.