Not often on this forum when a microbiologist like me has something substantive to contribute! First, let's see what the data really are here when the paper is released. It's pretty common for leaked press reports to mangle things. Second, it's alway good to be a bit skeptical when people are pushing up against the limits of what can reasonably be inferred from the data. It sounds like they have found chemical signatures suggestive of biological origin, which is not the same as, say, actual microfossils. That said, there is some value in considering how long things took to appear on Earth relative to the "lifespan" of sun-like stars. Signs of bacterial life can be found in rocks almost all the way back to when the Earth cooled enough to allow liquid water. On the other hand, eukaryotic cells (which have much more complex internal structures) do not appear until more than a billion years after that, and abundant, complex multicellular eukaryotes take more than a billion years after that. Technological intelligence takes "only" a few hundred million years after that (leaving aside the question of what steps come _after_ us). And as the Sun continues to brighten over time, in less than a couple billion years more, the Earth will no longer be able to sustain liquid water, so in the one example we have to work with, Earth will have spent most of its time in the Habitable Zone populated with single-celled life, but technological intelligence was a bit of a close call. Hope is that by studying the chemistry of promising targets over the next few decades (Mars subsurface, Europa, Titan, Enceladus, and perhaps spectroscopic analysis of extrasolar planets), we'll get a better idea of how likely life might be elsewhere.