Why do Presidents pardon turkeys?

Every year during Thanksgiving, the President of the United States "pardons" turkeys presented to him by farmers. How did this tradition begin? And what do they do with the "pardoned" turkeys?

Thanks to Google, I was able to research and write this "exposé" from the comfort of my home while I'm defrosting chickens. Apparently, most Presidents ate the turkeys they were presented with, and those that did not like turkey meat donated them to the local homeless shelter.

The turkey pardoning sort of started off as a joke by Ronald Reagan in the 1980s.

Reagan, who I guess was doing some sort of press conference, was asked before Thanksgiving whether or not he would pardon Oliver North for his role in the Iran-Contra deals. Reagan, in typical Reaganesque manner, deflected the question with a joke, saying he would pardon the turkey.

President George H.W. Bush later turned the turkey presentation, the Wednesday before Thanksgiving, into a turkey pardoning day. After the turkeys are pardoned, they're sent to some farm to live out the remainder of their lives. Although this begs the question, how long do the turkeys live afterward?

Domesticated commercial turkeys are bred to maximize weight gain in the shortest amount of time, which shortens their natural life expectancy to as short as two years for male and three years for female birds.

These "pardoned" turkeys don't live very long at all... maybe the Presidents should just donate them to the local food bank or something...