Companions for humans, cats have a long history of relationships. Several millennia are marked with feline loyalty. Although cats are the cause of allergy flare-ups, they are not a cause of harm for humans. Generally weighing between five and fifteen pounds, cats have a height and body length close to one foot. With specialized teeth, tongue, and ears, cats can use body language to communicate their mood. Their teeth are made for eating meat. Their tongue is barbed to aid in grooming and helps to spread their own natural deodorant. Their ears are able to detect high pitched sounds. Cats have more sensitive senses than humans and often sleep more to store energy.