I would have thought tigers are opportunistic hunters... humans are not it's natural food, but if there is nothing else going they will eat anything that moves, within reason. If the tiger is being taunted or perceives a threat in any way it will attack if cornered. They tend not to be overly aggressive animals in the wild... they don't fight unless they have to. There is a monastery in India where the monks rear tigers and they run around pretty much wild, they have food and are used to human contact... wonder why they don't eat people?