Getting back to my special topic, after a long lay off, let me start off with a question. How long does a civilization last, in all its glory. As pointed out earlier, none of the ancient civilizations ever died out entirely. The guys who lived in Mohan Jo Daro and Harappa quit long ago, leaving only the ruins. Most of us think we know what happened to the Mayans. Mesopotamia exists no more. But the people who created these ancient glories, are probably still around in some gene pool.
But that is not the question. The question concerns the peak and slow decline of these cultures. With my limited knowledge of history, it seems to me that the duration of the peak and the speed of decline, as wel as the speed of the ascend, have all accelerated.
Which, once more, brings me to my favourite topic: Do civilizations have something like half live for radioisotopes?. Funny question. But I suspect there is something in that.