It is only human beings that have verbal language naturally. We really do not teach our children to talk they acquire it as their brain becomes ready. If we want our pets to understand language we need to purposefully teach the meaning of a word and they likely will never learn to verbally respond to carry on a conversation. They only follow instructions. So the understand but can not produce language. The study of language if often attributed to Norm Chomsky. The developmental understanding of language is that there is a location in the brain that is mainly used to learn language. Newborns come fully equipped to learn language and to learn any language. Babies hear sounds called phonemes. These are not full words just sounds. Mothereeze is so interesting to babies (and helpful) because it centers on these sound. Babies will stop sucking to listen to mothereeze. It is thought that children are listening to these sounds even before birth. An infant will turn toward their own mother’s voice speaking mothereeze and not toward another mother. This likely indicates that the child is familiar with that voice of their mother’s and not the other voice. He/she has been listening in the womb. Cooing which happens at about 4 weeks old is imitating those phonemes. Later babbling is imitating the sentences. It begins to show sentence cadence and inflection. To go from babbling to speech the child must learn that words are symbols. Children soon recognize that words and objects are connected and they go from there very quickly. At two years, a child knows a few hundred works, by six he has a vocabulary of 10,000words.
After recognizing phonemes, children learn grammar. That sounds strange but it is true. So, while parents are busy enunciating words thinking baby is learning, the child is putting together the grammar rules in their language. That is why when a child is fist putting sentences together just past one year old, the child will say “Mommy goed to the store.” The rule for past tense in the English language is to add an ed. The child is following those rules it began to learn at birth. By the age of one the child knows 5 to 100 words and all the grammar rules they need. The area in the brain intended for language learning begins to be used for other things by the end of the third year of life. These first three years are the years to teach multiple languages. After they turn four they must learn language in another way (Like when you were learning a foreign language in high school) and it does not come as easily.
Theorists believe because of the adaptive nature of language learning that it suggest it has an adaptive origin. They think perhaps it is the FOXP2 gene that allows us to utilize language. Humans seem to have a unique form of this gene that seems to have appeared between 100 thousand and 200 thousand years ago.
Language and the brain
In most animals that communicate using sound, we know that language is centered in only one hemisphere of the brain (usually the left). This would include such animals as birds, dolphins, mice and to some degree monkeys. This is also true of humans. The right hemisphere control language in only 3 % of right handed people and 19% of left handed people.
There are basically two areas in the brain involved in language, Broca’s and Wernicke’s areas. Broca’s area is mainly responsible for putting sentences together using proper grammar and locally appropriate vocabulary. Wernicke’s area is responsible for language processing. That is, understanding the meaning of the words heard and then a ability to put words together to make sense to others. It is thought that other areas surrounding the Sylvian fissure, which is a line separating the parts of the brain that are only found in humans from those shared by animals, also has something to do with language production.
Evolutionary origin of language
One theory (Michael Tomasello and Talmy Givon) claims that we learn language by imitation which puts it in the category of learning. They do not believe that there is an innate grammar structure in the brain for language. That theory began before we had the valuable brain imaging we have now. They still say that since that portion of the brain that shows early language learning is taken up by other areas of the brain that therefore it is not language specific in nature.
Tecumseh Fitch says that it is impossible that every aspect of language is adaptive. He says instead that the evolutionary origin of language is best understood as resulting from the convergence of many different and separate adaptations coming together into one complex system.
Terrence Deacon, the author of The Symbolic Species believes that different aspects of language have evolved at the same time independently from one another but in conjunction with the general evolution of the mind. Therefore, the ability to use symbols is part of our whole cognitive evolution.
If we could agree on a single theory, we are still left with the most important question if we are to use this knowledge in the future and that is: which of the brains many functions has been the basis of the language adaptation? Several theories (as you likely expected) are out there. One theory is that it evolved for the purpose of social grooming. So, it is useful to humans for forming contracts, everything from mating contracts to business contracts.
It is likely that as needs have changed; the way in which we communicate has changed. Evolutionists study the difference between direct and derived functionality. Direct communication refers to the things that are responsible for reproduction and survival. Derived communication are the things we have found to use language with along the way. This may be something like using gossip to obtain socially acceptable outcomes. It may be that we are moving into an era of more derived evolution. We certainly have moved into a time of different kinds of communication much of it being digital. Where this research will take us and how it will apply to our understanding and use of psychology is yet to be determined. If nothing else we will likely be updating how we understand language as a part of human development.
The Evolution of Language Out of Pre-Language, Michael Tomasello, edited by Talmy Givón, Bertram F Malle