National Geographic TV has a show about wild pigs that's really interesting. They have one about eggs that worth seeing too.
One of the things that really surprised me on that show was that when a domestic pig escapes, or is released, and it lives off of the land, it's DNA changes. It actually becomes a different animal!!! It's ears stand up, it's tail straightens out, it grows hair and overall, it physically changes. This only takes a year to happen!!!!
There are no pigs native to North America. Javelina are not part of the pig family.
Pigs have no way of cooling themselves. They do not sweat like some mammals do, and they do not pant, like dogs do to cool off.
The show also talked about their social structure and how quickly they reproduce. It's really a worthwhile show to watch if you are interested in wild pigs.
In the back of my mind, it might of also talked about Hogzilla, and how some pigs can grow to a massive size. There was a lot of information in that show.