For those interested in going deep on this, I highly recommend this essay I was fond of in grad school by W. Ford Doolittle, who writes a lot on this subject: [Pattern pluralism and the Tree of Life hypothesis]([https://www.pnas.org/content/104/7/2043)
For a while now amongst evolutionary biologists it has been clear that the "root" of the evolutionary tree, or the so-called "LUCA" (last universal common ancestor) may not exist, mostly because horizontal gene transfer is so common amongst unicellular lifeforms that it ruins the orderly notions of descent-with-modification that we have formed following Darwin's studies of higher life.
I imagine this is disheartening to most people, and the orderly notion of a "tree of life" with a simple root persists because we want an uncomplicated picture of the world; human needs for ontological clarity trump the disgusting ball of muck and sputum that is actual life.
For a while now amongst evolutionary biologists it has been clear that the "root" of the evolutionary tree, or the so-called "LUCA" (last universal common ancestor) may not exist, mostly because horizontal gene transfer is so common amongst unicellular lifeforms that it ruins the orderly notions of descent-with-modification that we have formed following Darwin's studies of higher life.
I imagine this is disheartening to most people, and the orderly notion of a "tree of life" with a simple root persists because we want an uncomplicated picture of the world; human needs for ontological clarity trump the disgusting ball of muck and sputum that is actual life.