Ryan and Pitman made the suggestion in their book, citing the sudden appearance of fortification and/or violent ends to various older settlements in Anatolia, M.E., and possibly elsewhere. It's not unlikely that the population of that now-submerged area was very large, due to then-current climate possibly as large as the surrounding areas put together.
Some decades ago I saw an interesting National Geographic article about the excavation of a 50 foot high village mound in Bulgaria. The earliest pottery was lively and brightly colored. Then about 3,000 BC the potter was all dull gray or brown with no ornamentation but very well formed and smooth. My thought then was my gosh what happened to these people. Now I suspect that the women (pottery makers) were captured by invaders, their men and older children murdered and they were a sad and depressed female population whose lack of happiness and spirit was reflected in their pottery.