Likely as few as 2 or 3 created that population... A pot belly will grow some nasty long sharp tusks if allowed to. I seen a pet p-belly boar with 5 inch swords sticking out of his mouth...
I did a little pig farming as a boy. We bought 3 tri-color sows to add to our program and all we knew them as was "texas pigs"... The way they destroyed their young and behaved, I am positive we got suckered into buying wild pigs. The wild sows will kill their young under high stress.
The rest I learned first hand or researching to be a better trapper and hunter. Seen some odd things doing this, bullets, shot and even a 2.5-3 inch 4 blade broadhead in their shields...
Brent