Hello y'all,
First thing I want to say; longtime reader, first post. I would be 'lost' without DarkUfo :).
Second, on to Adam and Eve.
It's obvious they are Rose and Bernard NADLER (that's their last name). Why?
Also,the producers promised an anagram in the episode NOT IN PORTLAND as a clue to that mystery. "Only fools are enslaved by time and space" (of the room 23 video) can be re-arranged to form the phrase: "bones of NADLERS may lay lost deep in cave".
So no worries everyone, Sun and Jin are ok!
Rose and Bernard are planning to stay on the island. The beads signify their races: one black, one white.
Rose and Bernard skipped with many of the other 815ers back to the 1970s, where they lived alone in the jungle with Vincent, independent of DHARMA or the Hostiles. Rose told Jack that she and Bernard were "retired," and no longer interested in pursuing adventures. It is possible they remained on the Island in the 1970s, eventually dying or being laid to rest in the caves. Even if less than 40-50 years passed since their deaths, as Jack had postulated, their bodies would be plenty decomposed by the time they were discovered in 2004.
Bernard and Rose may be the two characters who help Jacob to win the argument of the goodness in humanity, as foreshadowed by the sentiments they expressed in the finale. This explains the significance of the skeletons.