The bursting of a land barrier between the Mediterranean and the Black Sea causing the latter to suddenly flood around 8 thousand years ago has been theorized. And discovery of what looks like outlines of old settlements on the Black Sea floor could be evidence. It certainly would fit the time frame and location of the tale of Noah. And genetic research says that at one point modern humans were reduced to a small group from which all of mankind today sprang. Personally I take Genesis as true as what people could understand and write down of stories about real events that had been passed down orally for perhaps thousands of years.