the Elder Pliny, The Natural History of Pliny, Volume 3…
“ Each pig, too, knows its own teat, according to the order in which it was born, and draws its nourishment from that and no other: if its own suckling, too, should happen to be withdrawn from any one of them, the pap will immediately dry up, and shrink back within the belly: if there should be only one pig left of all the farrow, that pap alone which has been assigned for its nutriment when born, will continue to hang down for the purpose of giving suck. ”
