Mostly I interpret this claim as "all -surviving- life is descended from a single ancestor cell," which leaves room for the idea of billions and billions of competing modalities whose descendants have all died off--or are yet to be discovered in the deeps. Or splashed out in the pores of asteroids cast adrift during the Heavy Bombardment.
But once a descendant from a competing progenitor is found, odds are really really good that a common ancestor for both progenitors will be proposed. But not absolutely certain.
Primarily, I'm attempting to establish the 'Tree of Life' as a continuous entity, and make the argument that organisms are an arbitrary definition. It seems like you're suggesting there might be an alternative strain of life that does not share the 'Last Common Universal Ancestor' (LUCA)? That may be true, but considering we are aware of all of the most prominent species of life on Earth, my desire to establish kinship between them is still valid.
I'm 100% behind the unification. Even without a common ancestor (though I do think it's hugely likely that all remaining life on Earth shares one) we share the environment that we can't be separated from if we want to thrive. Even if we established another line of life with different ancestry, we would be unified through how we affect and are affected by the Earth itself, our mutual host, and thus affect and are affected by one another--and less likely to thrive without each other. Because mutual interdependence eventually develops even between bitter enemies. It's just a fact of efficient resource management and optimization.
Further, to break the Earth-centric view in a universe likely to contain elements of life that are too distant from one another to be causally linked beyond the common origins of everything, we would still be united by the principles of entropy and energy dissipation that demand that life must exist wherever the potential for complexity is high enough.
Every planet might eventually settle on its own surviving tree, but there's still something that makes a bunch of individual trees into a forest, I feel, and it shouldn't matter how many trees there might be on any particular world. I hope.
Mostly I interpret this claim as "all -surviving- life is descended from a single ancestor cell," which leaves room for the idea of billions and billions of competing modalities whose descendants have all died off--or are yet to be discovered in the deeps. Or splashed out in the pores of asteroids cast adrift during the Heavy Bombardment.
But once a descendant from a competing progenitor is found, odds are really really good that a common ancestor for both progenitors will be proposed. But not absolutely certain.
Primarily, I'm attempting to establish the 'Tree of Life' as a continuous entity, and make the argument that organisms are an arbitrary definition. It seems like you're suggesting there might be an alternative strain of life that does not share the 'Last Common Universal Ancestor' (LUCA)? That may be true, but considering we are aware of all of the most prominent species of life on Earth, my desire to establish kinship between them is still valid.
I'm 100% behind the unification. Even without a common ancestor (though I do think it's hugely likely that all remaining life on Earth shares one) we share the environment that we can't be separated from if we want to thrive. Even if we established another line of life with different ancestry, we would be unified through how we affect and are affected by the Earth itself, our mutual host, and thus affect and are affected by one another--and less likely to thrive without each other. Because mutual interdependence eventually develops even between bitter enemies. It's just a fact of efficient resource management and optimization.
Further, to break the Earth-centric view in a universe likely to contain elements of life that are too distant from one another to be causally linked beyond the common origins of everything, we would still be united by the principles of entropy and energy dissipation that demand that life must exist wherever the potential for complexity is high enough.
Every planet might eventually settle on its own surviving tree, but there's still something that makes a bunch of individual trees into a forest, I feel, and it shouldn't matter how many trees there might be on any particular world. I hope.