A frog's tongue is anchored n the very front, unlike with the humans, simply because of their feeding habits. When a frog wants to eat, usually an insect, it will sort of throw its tongue outside in order to catch a fly or something, then wrap the tongue around the insect, and then withdraw the tongue inside its mouth in order to chew on its victim. Humans don't normally eat like this, which is why their tongues are anchored differently.