Hi, it is my suspicion that any true lost civilization was wiped out long before the Younger Dryas ecent of 12.8 kya. We are getting echoes of its existence from the evidence of human innocation coming out of the Qesem Cave, and relating to an epoch approximately 420 kya. See my new article [www.ancient-origins.net] The question becomes, if the Qesem individuals were so advanced, then what became of their descendants? What level of high culture did they achieve and when? I suggest that the Qesem individuals can be classed as proto Siberian Denisovans. If so then we know for certain that they achieved great things by the start of the Upper Paleolithic age, circa 45 kya. The Qesem individuals begin the transition from the Lower Paleolithic to the Middle Paleolithic, a transition that we might find was equally important in the emergence of human innovation.