Stinky was captured and enslaved by a group of soldiers lead by an ape hunter named Jakob Willits. Stinky was repeatedly tortured by the humans and branded with a number on the left side of his head known as their symbol, "2517".
Planet of the Apes: Last Frontier
Stinky fought alongside Willits and his army of soldiers against a tribe of apes at Miller's Bridge. Stinky is captured by the apes in the confusion and brought before their leader, Tola. After Tola's brother, Bryn arrives, Stinky tells them about his history and warns them of an army of soldiers arriving by train to kill them all. Tola sends Bryn to scout ahead and validate Stinky's story while taking him along as a guide. Stinky shows Bryn the camp of soldiers around a train they will use to transport themselves before Stinky flees the area. It is unknown if Stinky became a member of the tribe of apes that captured him or went to live on his own.