...Even non-opposable ones. Consider clever critters who do; consider the short life and illustrious career of escapologist, pacifist and ringleader Ken Allen. The orangutan.
Darned pity those guys don't have language -- I'm quite sure he was tryin' to tell the zoo something. Of course, the original people in those parts (edit: that would Borneo and Sumatra) claimed -- and may yet -- that orangs speak well enough but won't do it around people, lest they be rounded up and put to work. A wise judgment, were it true.