Q. How and why do cats pur?
A. The how is easier. Purring is produced by rapid, cyclic pressure changes in the trachea or throat of cats, caused by stimulation in the muscles of the larynx and diaphragm. That rapid process is controlled by a unique site in the cat's brain, which is why humans and other species can't purr. Why they do it has intrigued scientists for centuries. Researchers now know tha it is a voluntary act, controlled by the animal. But it is not just a sign of contentment. Badly frightened cats, severely ill cats and female cats delivering kittens also purr. For a complete answer, we will probably have to wait until genetic engineers produce cats that can talk. For more information, visit www.howstuffworks.com//question394.htm and wsiwyg://93http://www.zooclub.farpost.com/eng/cats/sost/4.htm.