For a century, anything small without a nucleus was a bacterium. Methane from mud and the pink of salt ponds were curiosities until molecules split the tree.
The 1977 rRNA paper did not instantly convince everyone. Lipid chemistry and later genomes made the domain unavoidable.
Timeline
Nineteenth-century chemists already knew marshes make methane. The microbes responsible were still unnamed archaea.
Culture work on methane bacteria begins in earnest; they are still filed under bacteria.
Carl Woese and George Fox publish 16S rRNA trees that peel archaea away from bacteria.
Unusual ether lipids corroborate that methanogens are not ordinary bacteria.
Halobacterium's purple membrane becomes a model for a light-driven proton pump.
Woese, Kandler and Wheelis formally argue for Bacteria, Archaea and Eucarya.
Methanocaldococcus jannaschii is sequenced — a hydrothermal methanogen with a surprising gene mix.
Lokiarchaeota genomes blur the archaea–eukaryote boundary and revive endosymbiosis debates.
Archaeal history is also the history of sewage works, rice paddies and hydrothermal vents.
Keep exploring
More in Tree of microbes
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Single-celled prokaryotes with cell walls ? the oldest widespread life form, and both partners and pathogens.
Familiarity 95Viruses
Packets of DNA or RNA that are not cells — they replicate only inside living hosts.
Familiarity 96Fungi
A eukaryotic kingdom of yeasts, moulds and mushrooms — chitin walls, external digestion, partners of plants.
Familiarity 80Bacteriophages
Viruses that infect bacteria — Earth's most abundant biological entities, and a concept-level idea in medicine.
Familiarity 42Protozoa
Motile unicellular eukaryotes — a teaching grade that includes pond ciliates and a minority of serious parasites.
Familiarity 58