One point to note is that humans evolved from apes at a quick pace. I've heard claims that longer life-span, the ability to engage in complex vocalizations, opp

One point to note is that humans evolved from apes at a quick pace. I've heard claims that longer life-span, the ability to engage in complex vocalizations, opposable thumbs, upright stance, binocular vision and so-forth are all pretty recent innovation over evolutionary short period, with large brain size turning out to be last addition. The human package might be not much more complex than "start with a rock-throwing mob and features providing benefits" So, on the surface, you could have a species that sprinted to all the features required for civilization - and then destroyed itself in a blaze of less-than-glory as we seem on a trajectory to do. Edit: Note, I should add that I'd actually doubt this scenario could happen only because the evolution of human seems part of the general acceleration of evolution that can be seen throughout geological history.