Human civilisation may be much older than we think. There are drowned structures governments and archeologists refuse to acknowledge lying about 100 feet down on continental shelves in a number of locations. As we know these only from Sonar images, the archeological fraternity, wedded as they are to the "Egypt is the start of human civilisation..." philosophy, refuse to acknowledge these and dismiss them as "natural formations". Having seen some of these on the sonar I would say that they are the first I've ever seen that run across tide and current flows and have right angled corners. I would suspect that Egypt, the Indus valley, Babylonian and Chinese may well have had forerunners that were submerged by the ice melt sea rises which hit around 12000 years ago, probably destroying whole civilisations as the land submerged. (What the AGW/IPCC mob say will happen to us...)