
Luca, the Ancestor of All Living Things - boulos
http://www.nytimes.com/2016/07/26/science/last-universal-ancestor.html
======
stillsut
I was thinking prions might be a good candidate for OOL.

Early Earth apparently was rich in amino acids and so chains of them may have
formed natural proteins. So a prion - a functional protein that can change
other proteins into its shape - would be able to set off an evolutionary
fitness search for the protein which could best "convert others" while
resisting being changed by others.

The other reason is I'm skeptical of starting with a polymer type information
encoding molecule. It seems too unlikely that any minimally viable genetic
molecule could assemble by pure chance and there is not a good way for
information to flow from the environment/cell -> genetic polymer.

~~~
ars
A prion can change the shape of other proteins, but can't make proteins.

~~~
gus_massa
I agree that prions are bad candidates. They can only change the shape of one
specific protein (perhaps a small family of proteins). To get something that
is barely alive it must be more general.

------
jessaustin
_Dr. Sutherland and others have no quarrel with Luca’s being traced back to
deep sea vents. But that does not mean life originated there, they say. Life
could have originated anywhere and later been confined to a deep sea
environment because of some catastrophic event like the Late Heavy
Bombardment, which occurred 4 billion to 3.8 billion years ago. This was a
rain of meteorites that crashed into Earth with such force that the oceans
were boiled off into an incandescent mist._

Kind of like _Seveneves_... If this hypothetical were true, we'd be at kind of
a dead end, wouldn't we? Any information we'd have about pre-Luca life would
either be represented somehow in Luca, or it would be completely gone.

~~~
Retra
That information could easily have been transferred to non-life in the form of
fossils, waste patterns, or 'trails' in various materials.

~~~
maxander
The oldest rocks on Earth that haven't been recycled by plate tectonics date
to about the same era, so there's not much of anywhere for these fossils or
etc to be.

