The size of the brain’s frontal lobes appear to differentiate humans from other members of the creature kingdoms. For example, a human’s frontal lobes comprise about 30 percent of the brain. In dogs, a comparable portion of their brain comprise about 7 percent (some dogs are capable of learning several hundred words but they do not articulate words as do humans). The comparable portion of the brain in cats is about 3 percent of the brain. Many people perceive they are able to have a more reciprocal relationship with a member of the canine family (as compared with the cat family). This perception may be related to the size of the brain area devoted to frontal lobes in relationship to the total brain size. In addition, humans have a pre-frontal cortex (right behind the forehead), which contains complex functions that it appears non-human brains do not contain.