It has nothing to do with pigs it is people. If a rattlesnake did not rattle a buffalo would step on them. So they rattled or died. But when people come along and they rattle we kill them. So if they rattle they die. It is just selective breeding. If only the ones that don't rattle live to breed then that trait is passed on.
I cant support this Warren.
The only rattle snakes that I have ever killed never rattled. The few that I have heard rattle sent me walking the other way!