When hollywood figured out that allowing the zombies run would save film, increase the threat from more zombies allowed differant type of fight scenes. For our fast food nation, as for brains zombies in the 1968 classic ate all parts of the body its only in retrurn of the living dead films that they eat brains which doesnt make sense as the skull is one of the thickest bones in the body a ombies wouldnt be abl bite through a skull.