Comment on If conditions on earth are perfect for life to form shouldn't have happened more than once?
Rhynoplaz@lemmy.world 6 days ago
I’m not convinced it’s only happened once.
A new bacterium could have been created in the ocean yesterday. How would we ever know?
AmidFuror@fedia.io 6 days ago
Assume you mean from simple building blocks instead of evolving from the reproduction of other bacteria, we could know if there were ever enough of this new bacterium for us to find and isolate it.
For one thing, if it didn't come from other living things it would not share the genetic code. Almost all organisms on earth use exactly the same translation of RNA codons to amino acids. The few exceptions are changes of just a couple of codons which had fallen to very low frequencies in the hosts' genomes.
That universal code is one of the reasons we know all life discovered to date evolved from a common ancestor.
A new bacterium, if it evolved convergently to use DNA and RNA and a 3 letter code (a big if), would not use the same translation as modern life. Even if there is some bias towards specific codons, the chance of the same core code happening twice is astronomically low.