Signs are calls to action, and are necessary for survival.
...like the days of the week, counting from one to ten, and others. Hence, swearing is not language. It is a sign of an emotional state . (See comments in Notes on swearing parrot.)
Up to this point, all of the types of communication we have discussed that were not language and based on signs. To a large extent we can see that signs are calls to action.
The dance of the bee, babies crying, cicadas buzzing, birds calling, dogs snarling, people raising their voices or swearing all demand some response--go there, feed me, hold me, stay away, etc.
Likewise, we have seen that signs are also very important, being necessary for survival. Where would the cicadas be if they couldn't communicate?
Notes: Click here for an experience with a Swearing Parrot