Language acquisition in humans is remarkably rapid and universal. Compare the nativist approach (Chomsky's Universal Grammar) with constructivist/emergentist perspectives. Create a theoretical analysis examining the arguments for and against each position, incorporating evidence from both typical and atypical language development. Consider the role of environmental input, cognitive abilities, and potential biological predispositions in language acquisition. How might these theories account for the critical period in language learning and differences in adult second-language acquisition?