The document discusses the critical period hypothesis (CPH) which claims there is a biological timetable for language acquisition. According to CPH, the critical period for acquiring a first language is earlier than for a second language. The critical point for acquiring a second language without an accent occurs around puberty. Beyond puberty, people have difficulty acquiring a new language in a native-like manner. The lateralization of brain functions provides evidence for CPH, as language functions become localized to the left hemisphere during a slow process completing around puberty.