A useful guide is to study previous collapses and apocalypses. We all know about the Dark Ages that happened after the fall of the Roman Empire, or the collapse of Mycenaean civilization and the following Greek Dark Age. These spasms occur quite frequently in history, but do seem to work themselves out in the long run. Rome seems to have crashed because it was just too big to manage, and in the Eastern Mediterranean the catastrophe may have been the result of the volcanic event at Thera. There seems to have been a major crash at the end of the Bronze Age, although prehistorians are still arguing about that.

There have been many other episodes like this, at smaller scales, all over the planet, throughout history. Is there a pattern to them, or are we imposing an order on human evolution that doesn't really exist? And remember, Egyptian civilization lasted about three millennia, as long as everyone else put together!

What I find disconcerting is that in most of our historical examples, the skills , technology and institutions survived at the local level, allowing civilization to rebuild. Consider, after the fall of Rome, every village in Europe had a functioning agricultural economy. People knew how to grow food. People also knew how to make pottery, build houses, construct ships, breed livestock, work metal, tan leather, weave cloth. Medieval architects couldn't match Roman builders at first but before long they were building cathedrals.

What worries me about future apocalyptic scenarios is that no one any more knows how to really DO anything. All of our skill sets are plugged into the system, without civilization, none of us knows how to grow food, work metal, navigate* a ship. I've always wondered if the most likely place for civilization to take hold again is India, where an established and stable village culture still exists that can keep food on the table and clothing on their backs. The ruins of cities will become quarries for raw material.

*Yeah, I know celestial navigation, but that relies on my having access to an accurate timepiece, a sextant, charts, a trig table or slide rule and an almanac (not to mention pencils and paper). After a year, most of this stuff would be useless. I could still do latitude sailing like the 18th century sailors, but in a few more years, even that would become impossible due to precession. My magnetic compass would probably last a lifetime, but I'd have no way to make a new one. What's the point of knowing how to drive a stick shift if there are no more cars? I could still sail a boat, but I'd have no knowledge or skills to build, repair or maintain one. I would probably outlast my tools, and I'd have little knowledge to pass on to the next generation.

I guess I could still get a job as a Fortran programmer.