Think about it. What is necessary for Darwinian evolution?
Nothing related to the beginnings of cellular life as we know it. Darwin was quite explicit about this. Darwinian evolution applies to the fossil record. What might has set it all off was beyond Darwinian ken, and he was quite careful to say so quite often, to avoid being embroiled in the abiogenesis debates.
Of course something way different, to which the Darwinian rules do not all apply, was going on before Prokariotes and Thermatoga made their debute. The only people surprised by this are the staunch proponents of the "whirlwind kind build a 747" argument as applied to Prokariotes.--who are, alas, mired hopelessly in last century's active debates on this subject.