Humans are a communicative species. Communication occupies a good deal of our time and energy. Our very existence and success as a species rests on our ability to communicate. We are not the only species that communicates information between individuals, nor even the only species to use language. While not unique, communications, especially via a language is used far more by humans than other species.
Language is used to move mental images from one brain to another. Species without language, and even those with, can move information in other ways like facial gestures, posturing, dancing, and odors. Language seems to add a precision lacking the others.
Humans appear to be genetically programmed to speak and understand language. Unlike other land mammals, our larynx (end of windpipe) does not lead directly to our lungs. Between four and six months of age, our larynx drops down below our tongue. The disadvantage is that you are more likely than a great ape to suffocate while choking on food. The advantage is that the greater breath control allows us to make a wider variety of sounds which we use to create linguistic concepts.
Most simply, languages consist of two types of words. There are those that cut the world into objects and words that link objects together. Nouns, adjectives and descriptors cut the world up. Verbs, adverbs and prepositions describe how the objects are related.
While human brains are hard wired for language, the specific sounds used to represent mental images are variable. The specific word used to represent "sister" or "love" is not genetically coded and will vary from one human group to another. Despite this variability, children learn to use language relatively easily.
By separating the information content of a word from a specific genetic code, the possible messages that can be sent between individuals becomes infinite. Language's survival value might lie in the fact individuals can pass on new information without waiting for the population's genetic code to mutate and adapt to new environments. Imagine if new words could be added to our language only after a mutated gene allowed us to speak the word. Similarly, our automobile culture would need more time to evolve if a society could drive cars only after they had genetically inherited the ability to recognize red octagons as the signal to stop. Language dramatically reduces the time it takes information to spread through a population.
Language has evolved to convey both referential and affective symbols. That is words can refer to specific objects like "rock" or "dog." But linguistic information is not merely housed in the words but also in how the words are vocalized. Much affective information is conveyed by tone and loudness independent of the actual words spoken. While words alone might not convey it, speech can communicate hate, outrage, sympathy, humor, compassion and similar emotional information.
Just as we crave food and biological necessities, humans crave exchanging mental images.
Primates in general spend a good deal of time socializing. Humans exhibit similar patterns and
have taken communications even further. Several of our more important technologies involve
enhancing our language and communications, including the World Wide Web through which
our interactions is being mediated.