CO-EVOLUTION OF THE HUMAN BRAIN AND LANGUAGE: A DISCUSSION OF HOW NATURAL SELECTION MAY HAVE EFFECTED BOTH THE PHYSIOLOGICAL AND NEUROLOGICAL CHANGES THAT BROUGHT ABOUT LANGUAGE AND SPEECH
During the Middle Ages, scholars accounted for human thought and speech by assigning a central part of the brain as the area where the "straw of raw sensory input got turned into the gold of thought" (Gutin 86). This is where the picture of the steeple and sound of the bell combined to mean "church" in the human brain. These scholars assumed that this area, which they called the common sensorium (where we get the term "common sense")(86), was the sole property of humans -- an idea that has persisted for centuries.
There have been many theories put forth since then as to why and how human speech has evolved and why animals do not seem to have the same capacity for language that humans do. This has been the primary motivation for attempting to teach non-human primates, who share 98% of the same genes that humans do, how to communicate (Hart 437). This paper will examine several different areas of theory regarding the co-evolution of the human brain and language, specifically, Chomsky's "Innateness Theory", how variations in climate may have changed the body through natural selection, how adaptations to complex communications may have spurred natural selection, and physical changes that needed to occur outside of the brain for speech to take place. First, however, there will be a brief section covering the background of the subject.
Ever since Darwin publish The Origin of Species in 1859, there has been conflict over the evolution of language. Max Muller, a leading linguist of his day, was of the opinion that humans and animals were irrevocably distinct, thus siding with Judeo-Christian ideology. Muller further declared language to be the boundary that "no brute will dare to cross" (Calvin and Bickerton 196). Darwin, however, was "fully con...