Before I'm torn to shreds for this theory, let me just say it's a longshot and is quite possibly inaccurate on many levels - here goes:
We know that Jacob knew Ilana personally from when he recruited her in the finale of season 5. Jacob didn't seem to know many of the characters that personally. Certainly not Ben. We can assume that he knew Richard personally, as Richard explained that he is how he is because of Jacob. If we are to believe that Richard was a slave on the Black Rock, could we assume that Ilana, Bram etc were also on the Black Rock and now don't age because of Jacob?
Shoot me down at your liberty, evidence against this will make things clearer :)