Whether language acquisition is a human instinct or not has been discussed and investigated by linguists for a long time. As human beings are able to respond and learn all kinds of language patterns that outsiders expose to them and children can come up with their own language, it's obvious to say that language is a human instinct. But children are not able to learn and master a language without being exposed to a normal language speaking environment which can be defined as a normal social life, leading to a more specific conclusion that language acquisition is a human instinct under the social condition.
Petitto' s Research program shows that when deaf children were exposed to sign language environment and hearing children were exposed to only spoken language environment, only sign language environment and bilingual environment respectively, they achieved identical linguistic milestones such as timing courses. This research reveals that baby can accept all kinds of language patterns inputted by environment and it occurs universally.
So it's not hard for us to reach that human brain possesses special biological function for language studies, which is our innate function.
Language acquisition is a human instinct also can be reflected by the creation of Nicaraguan Sign Language. Deaf students in the relatively isolated environment came up with their own language that linguist Noam Chomsky claims to have the "universal grammar". The birth of the language was driven by children's need to communicate with each other, which also symbolizes our human beings' instinctive need to express and to understand other people. The "universal grammar" implies that all kinds of human languages have grammars or rules in common. This coincidence suggests that humans all over the world have the instinctive ability to create languages that have similar structures.
However, without the language environment,