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?
"But I don't think this explains ALL life having a common ancestor as DNA suggest. Even plants and people have some common DNA."
The basic amino acids that make up life have been found in space.
Once life exists, it expands to fill every niche. After every mass extinction event in history, species adaptation has happened, and the world fills up again.
@ScottSoCal but vast sequences of DNA are identical for plants and humans