If we play that game this turns into All Good Things, and even if that's still my favorite TNG episode, it's hard enough to extrapolate alternate history when we have reliable records of events. When we get into anthropology rather than pure history we're forced to hope events have been accurately reconstructed without the benefit of first hand witnesses and THEN speculate on the outcome had events played out differently.

That's not to say the more challenging task isn't worthwhile, but it's not really "history" in the accepted sense, is it? I concede the world would be very different without the emergence of the first eukaryotes, but that happened so long ago and is so poorly documented that the effects would be impossible to predict with any certainty, however interesting they are to consider. "Awww... see what you did? "