Natural selection of the critical period for language acquisition.
The language acquisition period in humans lasts about 13 years. After puberty it becomes increasingly difficult to learn a language. We explain this phenomenon by using an evolutionary framework. We present a dynamical system describing competition between language acquisition devices, which differ in the length of the learning period. There are two selective forces that play a role in determining the critical learning period: (i) having a longer learning period increases the accuracy of language acquisition; (ii) learning is associated with certain costs that affect fitness. As a result, there exists a limited learning period which is evolutionarily stable. This result is obtained analytically by means of a Nash equilibrium analysis of language acquisition devices. Interestingly, the evolutionarily stable learning period does not maximize the average fitness of the population.
Komarova
N L
NL
Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540, USA.
Nowak
M A
MA
D005075:Biological Evolution; D003423:Critical Period, Psychological; D006801:Humans; D007804:Language Development; D007858:Learning; D008960:Models, Psychological; D012641:Selection, Genetic; D013997:Time Factors