You're the only one of (currently) four replies to correctly identify that the sentence is confusing because it's ambiguous what "first one" refers to, rather than because the GP doesn't know what archaea are or what "latter" means.

> The latter (archaea) were completely unknown until the first (archaea) were found in 1977.

Aha ! Thanks.

Quite frankly the rest of the article isn't easy to decipher either (but English isn't my first language).

The list of beliefs/theories that could change throws me off because some statements are about some topics that I thought most were in agreement (eg: the universe is expanding)

> Things will continue to change. Below I have put a few things that I think could change from now into the beginning of the next century.

> - The Universe is not expanding.

The cosmology list is more about fact waiting to happen that expansion of knowledge but I am just a layman.

What's the other interpretation of this sentence? "The latter" comes directly after an enumeration, with arachea as the last term. It seems pretty clear?