We don't. Then again we don't know what exactly Sylar can do or why he's doing it or why he's cutting all these people's skulls open or how he knows who has the potential for superpowers or if he knows their powers or why he picks one superhero over another or really anything, other than that he saw that one scene in Indiana Jones and the Temple of Doom with the monkey brains and thought, "YUM!"

In other words ...

*twirls*

Welcome to Conjectureland! We have ponies and cotton candy and theories based on very little evidence! ;)