Recent research indicates that pigs may be capable of recognizing themselves as individuals in a mirror. This would put them among the select group of creatures (including dolphins, elephants, and some primates) that are also known to be this intelligent.

My bf found an article in Spiegel and translated it to me from German. It references a study from the English journal Animal Behaviour which did show at the very least that pigs understood their position in relation to the mirror so that they could orient themselves to find (odorless) food correctly.  (The journal may require access, which I've got through my university...)  I'll post more English sources as I find them.  (Gotta do some homework first, then I'll investigate this further.)

I was already making an effort to eliminate pork, beef, lamb, etc. (all mammal meat) from my diet.  Now I vow with even more conviction never to eat pork.  I'm also making sure not to buy any pet food that contains pork or beef.  (Oh man!  Cat food is a whole other topic to be concerned with!  Recently I found out that most brands of cat food are absolute garbage, and some get away with price extortion to a ridiculous degree.  Don't be fooled by Science Diet.  Buy grain-free food for cats if possible.  Another post, later maybe.)

Oink Oink!