they are helping there salves all the time it does not matter here.

Well according to Wikipedia,

"The first computer mouse, held by inventor Douglas Engelbart, showing the wheels that make contact with the working surface.
The first computer mouse, held by inventor Douglas Engelbart, showing the wheels that make contact with the working surface.

Douglas Engelbart of Stanford Research Institute invented the mouse in 1963 after extensive usability testing. Engelbart's team called it "bug". It was one of several experimental pointing devices developed for Engelbart's oN-Line System (NLS). The other devices were designed to exploit other body movements—for example, head-mounted devices attached to the chin or nose—but ultimately the mouse won out because of its simplicity and convenience.

The first mouse, a bulky device (pictured) used two gear-wheels perpendicular to each other: the rotation of each wheel translated into motion along one axis. Engelbart received patent US3541541 on November 17, 1970 for an "X-Y Position Indicator for a Display System". At the time, Engelbart intended that users would hold the mouse continuously in one hand and type on a five-key chord keyset with the other."

Here's the link if you want to know more about the mouse. Goodluck!

DC

http://en.wikipedia.org/wiki/Computer_mouse

look for evidence such as poo or bits of food missing or somewhere else, pasta packets with holes in ect

They bite it right on the neck which usually kills it instantly.