Illiterate Medieval serfs could recognize heraldry - sometimes their lives depended on it. Head Start can get slum bunnies to echo "I want my rights!" after a few years of intensive training, practice, and free feeding (like training pigeons in a Skinner box). Language is more than semiotics. You speak a language when you can create something new within it.
Penny Patterson and Coco the gorilla (actual name: Hanabi-Ko; grandiloquent propagandistic spew) can converse in sign language. The gorilla made some headlines for telling Penny about a nasty toothache. Coco hasn't written a trashy novel, drawn images, or created music. Cracking a nut with a rock is not the same thing as building a doorway as an arch,
http://www.pitt.edu/~medart/menuglossary/arch.htm
When the gorilla makes puns and apolgizes for them, that's animal use of language.
