Ever since they were discovered in episode 1x06 "House of the Rising Sun," the two corpses by the inland stream have intrigued me. Discovered by Jack and Kate, and dubbed "Adam and Eve" by John Locke, these two bodies have been one of the island's deepest mysteries, and yet no one seems to be asking questions about them. It is my belief that all roads lead to whoever these two decomposed bodies end up being, and that it will be one of the final moments of Season Six when we finally discover the truth.
Look first to the January 31, 2007 interview that Damon Lindelof and Carlton Cuse had with Entertainment Weekly's Jeff Jensen. In it, a Q & A concerning Adam and Eve takes place; I've posted it below:
JENSEN: What is the meaning or significance of the two skeletons that Jack and Kate found in the cave of season 1?
CUSE: The answer to that question goes to the nature of the timeline of the island. We don't want to say too much about it, but there are a couple Easter eggs embedded in [the Feb. 7 episode], one of which is an anagram that actually sheds some light on the skeletons and hints at a larger mythological mystery that will start to unfold later in the season.
LINDELOF: There were certain things we knew from the very beginning. Independent of ever knowing when the end was going to be, we knew what it was going to be, and we wanted to start setting it up as early as season 1, or else people would think that we were making it up as we were going along. So the skeletons are the living — or, I guess, slowly decomposing — proof of that. When all is said and done, people are going to point to the skeletons and say, 'That is proof that from the very beginning, they always knew that they were going to do this.'
Now, what is most intriguing about this response is that both men tap into some very well-processed ideas. Lindelof, for instance, makes certain that it is realized: they have had a plan for Adam and Eve from the beginning. And since the two writers have said repeatedly that they discussed who of the main characters would live and who would die before the Pilot was even scripted, we can assume that the corpses will belong to someone we know rather closely. This, in my opinion, excludes some fairly obvious people; Ben (because he wasn't created yet), Juliet (same), Faraday (unless they planned WAY ahead), Alpert (nah), and so forth. Further more, I believe that the two corpses belong to members of Flight 815. I'll explain more on that later.
Back to the interview, it is Cuse's words that drop the most hints. He mentions the Easter Eggs that are planted throughout the February 7th episode, #3x07 "Not in Portland," the one pertaining to the skeletons being an anagram. Unfortunately, even after close analysis, the only true anagram discovered in "Portland" was the name of Richard Alpert's fake company Mittelos, while rearranges into Lost Time. As we know by now, in the middle of season 5, time on the show LOST passes alot more differently than it does in the real world, particularly when turning the Frozen Donkey Wheel can send you to 1974 and beyond. It's my opinion that Lindelof and Cuse were, at the time, giving reference to the idea of 'whatever happened happened,' and that perhaps, with the Island jumping around in space and time, a 1974 person could confront the 2008 version of themselves if so inclined.
So in the end, what do we know about the two bodies left decomposing by the river? Not much, except that the ideal of time in this show plays heavily into the plausibility of the skeletons existing. What does this mean? It means that I've developed a theory -- when they stumbled across Adam and Eve, Jack and Kate inadvertanly discovered their own bodies from another timeline. Therefore, before Flight 815 ever crashed on the Island, Jack and Kate were already there, passing away with one another close by their side. This would play heavily into the concept of the time loop Horace is stuck in; and while they may not be jammed in time like he was, the concept of time travel and being two places at once is taken to whole new levels with this situation.
That's my two cents. Jack and Kate will pass away near the end of Season Six, and decompose into Adam and Eve nearly ten years before they again crash onto the Island on Oceanic Flight 815. If this happens, it will be the ultimate form of redemption: a woman who always runs away settles down with a man who, while he used to always need someone, is willing to sit back and let whatever happens happen. As for the white and black gem stones that Jack finds on the male corpse, we'll just have to wait and see.
[EDITOR'S NOTE: As for why I didn't say it was Desmond and Penelope, or Sun and Jin -- both couples have a kid, and that would just be too cruel.]
[EDITOR'S NOTE #2: The irony of Adam and Eve being in the beginning of the Bible, and the end of LOST, would ring awesome on so many levels.]