This falls in line with the theory that as our brains became larger, our cognitive functions increased.
The other competing theory, posed by linguist Noam Chomsky and evolutionary biologist Stephen Jay Gould, is that language evolved as a result of other evolutionary processes, essentially making it a byproduct of evolution and not a specific adaptation. The idea that language was a spandrel, a term coined by Gould, flew in the face of natural selection. In fact, Gould and Chomsky pose the theory that many human behaviors are spandrels. These various spandrels came about because of a process Darwin called "pre-adaptation," which is now known as exaptation. This is the idea that a species uses an adaptation for a purpose other than what it was initially meant for. One example is the theory that bird feathers were an adaptation for keeping the bird warm, and were only later used for flying. Chomsky and Gould hypothesize that language may have evolved simply because the physical structure of the brain evolved, or because cognitive structures that were used for things like tool making or rule learning were also good for complex communication. This falls in line with the theory that as our brains became larger, our cognitive functions increased.