It's a possibility that the numerous flood myths that have survived have their origin in post-glacial sea-level rises around 8-6000 BC. In some cases these were accompanied by catastrophic events, for example the Storegga Slide which may have caused the tsunami that finally inundated 'Doggerland', the land bridge between Britain and mainland Europe. Certainly these sea level changes would have removed ancestral hunting grounds and migration routes. It must have had a heck of an impact though for the tale to survive 3,000+ years until someone thought up writing.