I believe Richard Alpert appears ageless because he is immortal. Jacob is the reason Richard does not appear to age. The big question is why Jacob would have done this to/for Richard. Apparently, this Locke-a-like/Mr. X/Esau/Whatever you want to call him (the man who was speaking with Jacob in the beginning) was able to 'impersonate' dead John Locke. Let's assume that he can impersonate other dead people as well (Locke was just the 'key' dead guy needed to influence Ben to kill Jacob blah blah blah).
So this Locke-a-like wants to kill Jacob, and he can impersonate dead people. This would make it really hard for Jacob to trust anyone. How could he be sure that whomever he was speaking two wasn't just Mr. X impersonating someone who was dead?
So we have Richard. Jacob met Richard and deemed him trustworthy. Therefore, Jacob made Richard immortal (which is why he appears ageless) so he could have one advisor that he KNEW he could trust. If Richard cannot be killed, then Jacob would KNOW that Mr. X wasn't impersonating a dead Richard. This would make Richard the only person on the island that Jacob could truly trust.
So this Locke-a-like wants to kill Jacob, and he can impersonate dead people. This would make it really hard for Jacob to trust anyone. How could he be sure that whomever he was speaking two wasn't just Mr. X impersonating someone who was dead?
So we have Richard. Jacob met Richard and deemed him trustworthy. Therefore, Jacob made Richard immortal (which is why he appears ageless) so he could have one advisor that he KNEW he could trust. If Richard cannot be killed, then Jacob would KNOW that Mr. X wasn't impersonating a dead Richard. This would make Richard the only person on the island that Jacob could truly trust.
