128
All Life on Earth Comes From One Single Ancestor. And It's So Much Older Than We Thought.
(www.popularmechanics.com)
this post was submitted on 15 Jul 2024
128 points (97.8% liked)
science
14563 readers
1265 users here now
just science related topics. please contribute
note: clickbait sources/headlines aren't liked generally. I've posted crap sources and later deleted or edit to improve after complaints. whoops, sry
Rule 1) Be kind.
lemmy.world rules: https://mastodon.world/about
I don't screen everything, lrn2scroll
founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
That they say it existed in the middle Hadean is striking. It was grabbing a toehold even when our world was a literal hellscape.
I think it increasingly likely that DNA first formed in space when the ambient temperature of the universe allowed liquid water. How else does a LUCA appear as if life on earth was a fait accompli, in the wake of a collision with another planet no less.
Edit: probably not
Planet: is actively boiling rock
Life: Its free real estate!
Microbes usually like it warm. Actively boiling rock seems like it would be pretty warm.
Among all the shit this [insert time period here], your comment got me to fully belly laugh. So thank you.
well, we need RNA before DNA. and we already have rna origin theories, so no, space dna doesn't seem to fit there as an emergent property of rna to self replicate.
here's a good one https://en.m.wikipedia.org/wiki/RNA_world
Actually this makes sense in the context of autocatalytic sets hypothesis - you'd need large variety of inorganic compounds and a strong energy gradient to kickstart a metabolism.
There's great video on the subject from Sabine Hossenfelder https://www.youtube.com/watch?v=7yOiZLHDV3U
Part I'm talking about starts at 15:48
What do you mean liquid water in space? Liquid water doesn't exist at low pressures, so you also need a somewhat pressurized environment like an atmosphere
I could be mistaken but I believe the hypothesis is that at one point the universe had an average temperature and matter distribution (pressure) to make it so that in most or at least a large portion of the universe it was significantly easier for organic molecules to start forming including the building blocks of DNA and then when it cooled/expanded some of that organic matter made its way to earth to eventually turn into life.
MMm... Probably not, at least in mechanism.
The issue is that of concentration. You need some kind of biogeochemical cycle that creates a concentration gradient. Otherwise the basic components are too diffuse to do anything meaningful.
I still lean into the "volitile ice balls" theory. NHx, NOx, Ox, etc. as volatile ices on asteroids in orbits where the iterate between freezing and melting. Moving between freezing and melting creates the biogeochemical cycle necessary to concentrate the basic elements sufficiently to be meaningful.