User blog comment:PhoenixRising101/Zoan Talk/@comment-31.205.64.145-20120212210258/@comment-4812569-20120212222931

Enlightment only goes to the people and animals that eat their own type of zoan fruit, not just the hito hito no mi. chopper was originally a reindeer, so thats why he can communicate with animals and eating the hito hito no mi enabled him to learn human speech.