For more than 150 years ago, the assumption that language is a singular event has hampered progress in explaining its evolution. Another obstacle was the failure to recognize that certain social interactions, uniquely human interactions, are necessary for the evolution of language.
These problems have been recently remedied by recognizing that words had to evolve before grammar and discovering non-verbal emotional and cognitive relations between an infant and caregiver. As I elaborate below, those relations are known as intersubjectivity and joint attention.
Darwin argued that the theory of evolution could account for the transition from animal communication to language by the principle of natural selection. The idea was that “language differed in degree and not kind” from animal communication. What remained to be discovered was the degree–“innumerable gradations” that separated them.
Some of those gradations have been discovered in recent years. But their nature suggests that language differs in kind from animal communication. With Darwin, Alfred Wallace, who published the first article on the theory of natural selection, wondered how natural selection, which assumes the survival value of a new ability, could account for man’s “superior intelligence.” Compared to apes, Wallace couldn’t understand why natural selection would produce anything more than a slight increment in mental ability. Language, not to mention numerical knowledge or music, is hardly necessary for survival.
Because Wallace assumed that language was a singular event, he didn’t realize that words had to evolve before grammar. If he did, he might have recognized how a theory of the evolution of words would be consistent with the principle of natural selection.
Before words could evolve, some of our ancestors had to become more cooperative than apes. That increment in cooperation was necessary for intersubjectivity and joint attention to evolve. To see how language’s verbal and non-verbal components relate to one another, it is helpful to review why chimpanzees, our nearest living relative, can’t learn language.
Read more: Psychology Today