Today my husband asked me (because he thinks I know every damn thing for some reason)
"why can new life just start evolving now in some primordial soup from scratch like it did long ago? Why aren't there many different evolutionary trees with different starting points? Why one big tree?"
uuuuh I have some guesses but I don't know. 🧵
My guess is that:
1. Life changed the composition of the atmosphere, weathering of rock, the seas everything. So it's just not the same now.
2. Nothing as simple as early life, which might not even have cell walls could cut it in the hurly burly of a modern puddle. So maybe it happens but never goes anywhere.
But I don't think this explains ALL life having a common ancestor as DNA suggest. Even plants and people have some common DNA.
Is there some other factor?
@futurebird Is the question why doesn't some "competitor" to DNA emerge- some other self-replicating molecule?
Perhaps the formulation of DNA truly is a one-in-a-<extremely big number> event. Like the chances of a bunch of atoms combining into a molecule that replicates itself are so small that it is unlikely for it to happen again for eons and eons.
Instead, all life is simply building off of that incomprehensibly rare event.
@escarpment @futurebird what I'm saying in a roundabout way is that we have a single origin in part because the software we use to generate visualisations assumes a single origin.
@gringene @futurebird Can you clarify? Are you using "visualization software" as a metaphor?
There is a theory that plant cells somehow... ate... but kept alive photosynthetic bacteria that are now the chloroplasts. Likewise what is up with the mitochondria with their own genetic system?
Is this the result of symbiosis gone wild?
Will Acropyga ants someday merge with the little obligate mutualist (domesticated er myrmesticated) mealybug they carry on their nuptial flights?
@futurebird @escarpment @gringene
Parasitic becomes symbiotic becomes a single organism, over time. That's how it's always been explained to me.
