Evolutionary psychology of language
[2] Noam Chomsky spearheaded the debate on the faculty of language as a cognitive by-product, or spandrel.
[4] He criticizes some strands of evolutionary psychology for suggesting a pan-adaptationist view of evolution, and dismisses Pinker and Bloom's question of whether "Language has evolved as an adaptation" as being misleading.
[4] He argues instead that from a biological viewpoint the evolutionary origins of language is best conceptualized as being the probable result of a convergence of many separate adaptations into a complex system.
[5] Exaptations, like adaptations, are fitness-enhancing characteristics, but, according to Stephen Jay Gould, their purposes were appropriated as the species evolved.
[8] The Baldwin effect provides a possible explanation for how language characteristics that are learned over time could become encoded in genes.
In the 1980s, psycholinguist Myrna Gopnik identified a dominant gene that causes language impairment in the KE family of Britain.
Children that grow up in a stable environment develop highly proficient language without any instruction.
Individuals with a mutation to their FOXP2 gene have trouble mastering complex sentences, and shows signs of developmental verbal dyspraxia.
[10] Humans have a unique allele of this gene, which has otherwise been closely conserved through most of mammalian evolutionary history.
By some classifications, nearly 7000 languages exist worldwide, with a great amount of variation thought to have evolved through cultural differentiation.
There are four factors that are thought to be the reason as to why language variation exists between cultures: founder effects, drift, hybridization and adaptation.
Comparative studies of the sensory-motor system reveal that speech is not special to humans: nonhuman primates can discriminate between two different spoken languages.
[13] Koko and Nim Chimpsky are two apes that have successfully learned to use sign language, but not to the extent that a human being can.
