One of the most controversial hypotheses for the origin of the human language faculty is the evolutionary conjecture that language arose instantaneously in humans through a single gene mutation.
…[R]esearchers have applied a variety of techniques from theoretical biology to the question of how to quantify the probability of a complex trait like language evolving in a single step, in many small steps, or in a limited number of intermediate steps, within a specific time window and population size.
Researchers concluded that, instead of a single mutation with an extremely large fitness advantage, the most likely scenario is one where higher number of mutations, each with moderate fitness advantages, accumulate. “A scenario in which the genetic bases of our linguistic ability evolved through a gradual accumulation of smaller biological changes. This scenario can be articulated in many different ways, for instance, as syntax evolving from phonological form, from rapid manual actions or from much simple pragmatic sequencing of words,” said [researcher Cedric] Boeckx.
Researchers explained that the evolution of something as complex as human language deserves integration of results and insights from different corners of the research landscape, namely the fields of neurobiology, genetics, cognitive science, comparative biology, archaeology, psychology, and linguistics.