Lisa, when gymeejet comes up with the "humans = tasty" scenario -- it's a reference to a well-worn hypothetical that is often used in undergraduate philosophy classes.

This hypothetical has been around for a good thirty years, if not more.

(In fact, someone's actually written a novel based on this hypothetical. Can't remember the guy's name, but the title of the book is "Under the Skin." It's written from the point of view of a race of aliens who come to this planet and start harvesting human beings for food. Some bleeding heart liberal alien comes along at some point and says something like "Well, shoot, shouldn't we be compassionate to these poor animals and leave them to live their lives in peace?" The other aliens say "Are you kidding? We're hungry. We need the food. Anyway, look at them. They walk on two legs. They don't speak our language. They have no culture to speak of. They can't even accomplish inter-galactic travel. They're stupid, and we're hungry. You can't possibly think we should sacrifice our well-being for the sake of this clearly inferior species.")