The type of sounds humans make also give evidence that language is a biological capacity . Other evidence that humans are developed with an innate ability to use language can be seen in patients who have suffered from brain damage. The left hemisphere of the brain has a dominance where language is concerned. When this part of the brain is damaged language and speech are very often affected. Illnesses such as Anomic aphasia often occour.
Anomic aphasia is characterised by difficulties in finding the appropriate words in speech.
For example, a person suffering from it knows that a clock is for telling time, but they can't quite grasp the vocabulary that it is in fact a clock. Anomic aphasia may be produced by damage to any part of the cortical language system and many other cortical areas as well. The very fact that language is effected by damage to the human brain is strong evidence to suggest that language is a biological capacity. Darwin's theory of natural selection has led to studies relating language to a biological capacity. Pinker and Bloom for example outline how natural selection can be applied to language.