Our southern hogs are traced back to the Spainards with Desota expeditions and others that followed him. My favorite deer stand is on the "Desota Trail" on the Big River but that another story......We call our hogs ferral hogs which means domestic hog turned wild. We have ferrel cats , ferrel dogs and we had a one time ferral Emus and a peacock at the Paradise....still another story... However 100% of the hogs I have killed in Ga, Fl and Sc were ferrel hogs from what was the Essex breed. The Essex breed was a popular breed of hog used in the south around 1800's and early 1900 for meat and LARD..They would really put it on after they were casterated. This hog was a predominately black swine with single hair follicle and NOT like the hair of an imported Russian or Belgium hog you see at some fence places.
I would suspect the west coast hogs have a strong background from the polynesian hogs that were dropped off by Capt Cook and others. But with the recent (in last 200 years) settling of the west, I am sure some eastern hogs made the wagon trip and/or train ride.
Interesting enough we now have a ferral Vietinese Potbellied hog showing up recently in mid ga. on some selected tracts .Pet owners turning these pets a loose..Old hogs do die in the woods....their skulls do rot or squirrels chew them up, or deer eat nibble on them but due to TB, hunters, depredation hunters, floods and general sickness,, the ole boy has a hard time making it very old...An average wild ferel hog will gain under decent mast and floral conditons 60# a year...a farm hog will gain what 200#..... so think about how many hogs see in a pack......you might see one large mature 200# -350# every so often....they a far and few between. A mature boar can rome a 100miles in a summer along a tributary..He's bound to run into a hog cowboy and a bulldog, depredation poison,trapped or sickness.....he has got it tough.... I admire these animals greatly....intersting past about them although they are basically scorned by the QDM deer hunting crowd..