[notfed]

Agreed that modelling it as a "pathogen" is missing the mark.

But predatorless photosynthetic self-replicating gray goo that grows exponentially across the planet, resulting in a drastic change in CO2 and oxygen levels across the globe? Wouldn't be the first time. [1]

[1] https://en.wikipedia.org/wiki/Great_Oxidation_Event

[mlyle]

Presumably that's gotten a lot harder/less likely given that we've had billions of years since and life fills a lot more niches. But that's not really something to bet civilization on without a bit more evidence.

[aydyn]

The difference is there is competition now.