ABSTRACT
Natural languages are distinct from such artificial languages as specially designed international languages for human use (e.g. Esperanto, Ido, Volapük) or programming languages for computer use (e.g. Fortran, C++, Java) in many ways but, most significantly, in the manner they are acquired rather than learned by the users. A live natural language is seemingly effortlessly acquired by the native members of its speech community, often after a pretty minimal exposure to it, by the age of 30 months or so. This natural language acquisition faculty remains active for a few years and starts fading to disappear entirely in most individuals by the end of their preteen years. Artificial languages, along with foreign natural languages to which an individual may be exposed later in life, have to be learned at a significant cognitive and temporal expenditure; in the case of a foreign language, a foreign accent is a sure give-away sign of the language having been learned rather than natively acquired.
