I am glad you find the conversations interesting, so do I.
As I write in my book, Crete has been an island for the past 5 million years. However, archaeological findings on Crete, attributed to Homo Heidelbergensis and Homo Erectus, show that these two species had reached Crete by sea 130.000 to 700.000 years ago. The Paleolithic positions which were investigated were in caves that at that time were coastal.
Since less advanced human species were crossing the seas so easily and so early on, I have every reason to believe that modern humans (Homo Sapiens) may have been doing it too ever since they appeared on Earth.