Domesticated animals often show signs of pleasure and relaxation when being rubbed, massaged or otherwise petted by people. Now researchers think they know why: it mimics the animals' social caressing.

Joanne Ritter, spokesperson for Guide Dogs for the Blind, told Discovery News that spending quality time with pets might be good for both the health of the pet and the person.

Ritter explained, "We know that petting dogs can lower the blood pressure of humans, so we are very interested to learn that we might be doing the same for them."

http://dsc.discovery.com/news/2007/05/09/petting_ani.html

Humpin' the animals is also a good way to show them affection and relieve stress. And guess what, these specific animals end up for sale in your local super market!