Eugen Rosenstock-Huessy, in his book, "Origin of Speech" proposes that human beings require rituals and tangible signs to establish an orderly environment, and control this environment based on the power exerted through speech.
Read a paper by Charles F Hockett, on the origins of speech and the 13 design-features of language.
A saying from the Vedas claims that "Speech is the essence of humanity." Speech and writing, are the ultimate tool for expressing ideas and actions. The New Testament states, "In the beginning was The Word. And the Word was with God and the Word was God..." In Buddhist and Hindu practices, the chanting of mantras, or recitation of verses, is an essential spiritual practice.