The story of your pre-historic ancestors' trip across the Pacific is interesting, but have you ever wondered what provoked their curiosity in the first place?
Have you ever seen the movie "What the 'Bleep' do you know?" There is a story of the first contact between Europeans and Native Americans, who we are told could not recognize the Europeans' ships at first because ships had yet to be introduced into their reality/consciousness or conscious minds. It involves quantum physics, but since I'm not a scientist I'm not going to try to explain it merely reccommend that you view the movie.
There is also a West African story about a journey across the Atlantic, I can't recall to which West African people the story belongs, but the journey was pre-colombian. I have a theory that the curiosity which prompted both journeys stem from a previous knowledge/awareness. Somewhere or something in the DNA of these people convinced them that the journey was not without reward because it was accomplished in the past. Whether that knowledge was written in their DNA or told from generation to generation Jheli/Griot style.
As a child of colonialism, I learned that Pre Colombian Europe thought the world was flat and sailing West mean't you were liable to fall off the face of the earth; so before I discovered that Colombus had considerable contact and was quite familiar with Portuguese sailors and cartographers, I credited him with much more wisdom than he deserved. When you factor into the situation Portugese contact with Western Africa all Colombus really should be given credit for is a pair of large ones and greed.
I say this to suggest that your ancestors' trip across the Pacific might not have been as spontaneous as you perceive, but a desire based on prior knowledge; that so human desire to return home. This suggests a different model than the European model of gene flow or genetic inheritance for the first Americans; and according to the BBC the Australoid del Fuegians were in Brazil as long ago as 50kya, now how do you reconcile that date with the currently accepted date for your ancestors arrival in Australia. It would suggest that they took the same amount of time to cross from Timor to Australia as it took for them to cross from Australia to Brasil. Compare links
As for your biblical flood I suggested in the past that since these flood myths are global and that your "world is the limit of your horizon", then the cause of the flood might have been localized, and I'm not willing to guess where, but its effects might have been far reaching. As in the effects of the tunguska phenomenon and Krakatoa. As our recent experiences with the Indian Ocean Tsunami and Iceland's volcano eruption. I'm not willing to hazard a guess at the level of destruction, that recently discovered undersea volcano might cause if it erupted in our lifetime, but one must accept that there's nothing solid about the ground we stand on, no matter the location.
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