| Definition -
A theory proposed by Noam Chomsky (and his followers) which claims that all humans are born with a specific, human capacity for acquiring language. This hard-wired capacity is what Chomsky calls the universal grammar.
1. A 2011 study used methods from evolutionary biology to trace the development of grammar in several language families. It concluded that cultural evolution, not the brain, drives language development. "These findings support the view that — at least with respect to word order — cultural evolution is the primary factor that determines linguistic structure, with the current state of a linguistic system shaping and constraining future states."
To read the complete article (Evolved structure of language shows lineage-specific trends in word-order universals (Dunn, Greenhill, Levinson, and Gray), click here.
Quotation - Chomsky clarifying UG: “It's virtually a truism. There are people who misunderstand the term but I can't deal with that. It's perfectly obvious that there is some genetic factor that distinguishes humans from other animals and that it is language-specific. The theory of that genetic component, whatever it turns out to be, is what is called universal grammar.”
(Source: Slate interview with Chomsky )