While the fine distinctions in defining and counting species are interesting, it seems that a key issue is related to the Fermi Paradox, Drake Equation, and the

While the fine distinctions in defining and counting species are interesting, it seems that a key issue is related to the Fermi Paradox, Drake Equation, and the Great Filter question. How many separate times did potentially technological-level intelligence arise separately (and how separately)? Is it fairly likely to arise from a range of environments and evolutionary paths, or is the evolution of technological humans an absurdly unlikely fluke? Are these multiple potentially technological species likely, and once one species gains technological advantage, it just dominates, or did just one 'branch' arise, most of the 'twigs' die out, and we've been just a bit more lucky so far? My guess is that the more branches, and the further back in the tree they occur (i.e., further back than higher intelligence develops), the more likely it is overall that we are not alone, but we'd need a lot more information to make that call.