Now my mom's and my theory on that was that Adam and Eve were actually Desmond and Penny. Because the creators of the series have said that Desmond and Penny are central to the mythology of the island. So my guess is that Ben killed Penny. And Desmond will be heartbroken. But he, like Locke, is special and therefore exceptions are made for him. So, in order to get Penny back, he'll have to go the island again. And then I'm guessing that maybe it'll be like if, once Penny is alive and on the island or something, they can't ever leave the island again. Yeah, I know this is kinda far fetched. But what the heck, the whole SHOW is far fetched! lol ^_^