A language is a system, used for communication, comprising a finite set of arbitrary symbols and a set of rules (or grammar) by which the manipulation of these symbols is governed. These symbols can be combined productively to convey new information, distinguishing languages from other forms of communication. The word language (without an article) can also refer to the use of such systems as a phenomenon.
Human languages use patterns of sound for symbols. These sounds can be converted into written form with little loss of information. Gestures are a part of human language too. Some invented human languages have been built entirely on visual cues to enable communication. In human languages, the symbols are sometimes known as lexemes and the rules are usually known as grammars. „Language“ is also used to refer to common properties of languages. Language learning is normal in human childhood and is biologically driven: a crucial role of this process is performed by the neural activity of a portion of the human brain known as Broca’s area. There are thousands of human languages, and these seem to share certain properties (called: Universal Grammar) as shown by generative grammar studies pioneered by the work of Noam Chomsky, even though many shared properties have exceptions. Recently, it has been proved that a dedicated network in the human brain (crucially involving Broca’s area, a portion of the left inferior frontal gyrus), is selectively activated by those languages that meet the Universal Grammar requirements.
There is no clear distinction between a language and a dialect, notwithstanding linguist Max Weinreich’s famous aphorism that „a language is a dialect with an army and navy.“ In other words, the distinction may hinge on political considerations as much as on cultural differences, distinctive writing systems, or degree of mutual intelligibility.
Humans and computer programs have also constructed other languages, including constructed languages such as Esperanto, Ido, Interlingua, Klingon, programming languages, and various mathematical formalisms. These languages are not restricted to the properties shared by human languages.
Human languages
Human languages are usually referred to as natural languages, and the science of studying them is linguistics.
Making a principled distinction between one language and another is usually impossible. For instance, there are a few dialects of German similar to some dialects of Dutch. The transition between languages within the same language family is usually gradual (see dialect continuum).
Some like to make parallels with biology, where it is not always possible to make a well-defined distinction between one species and the next. In either case, the ultimate difficulty may stem from the interactions between languages and populations. (See Dialect or August Schleicher for a longer discussion.)
The concepts of Ausbausprache, Abstandsprache and Dachsprache are used to make finer distinctions about the degrees of difference between languages or dialects.
Origins of human language
No one yet agrees on when language was first used by humans (or their ancestors). Estimates range from about two million (2,000,000) years ago, during the time of Homo habilis, to as recently as forty thousand (40,000) years ago, during the time of Cro-Magnon man, to Biblical eden-times six thousand (6,000) years ago.
Language taxonomy
The classification of natural languages can be performed on the basis of different underlying principles (different closeness notions, respecting different properties and relations between languages); important directions of present classifications are:
• paying attention to the historical evolution of languages results in a genetic classification of languages—which is based on genetic relatedness of languages,
• paying attention to the internal structure of languages (grammar) results in a typological classification of languages—which is based on similarity of one or more components of the language’s grammar across languages,
• and respecting geographical closeness and contacts between language-speaking communities results in areal groupings of languages.
The different classifications do not match each other and are not expected to, but the correlation between them is an important point for many linguistic research works. (There is a parallel to the classification of species in biological phylogenetics here: consider monophyletic vs. polyphyletic groups of species.)
The task of genetic classification belongs to the field of historical-comparative linguistics, of typological—to linguistic typology.
See also Taxonomy, and Taxonomic classification for the general idea of classification and taxonomies.
Genetic classification
The world’s languages have been grouped into families of languages that are believed to have common ancestors. Some of the major families are the Indo-European languages, the Afro-Asiatic languages, the Austronesian languages, and the Sino-Tibetan languages.
The shared features of languages from one family can be due to shared ancestry. (Compare with homology in biology.)
Typological classification
An example of a typological classification is the classification of languages on the basis of the basic order of the verb, the subject and the object in a sentence into several types: SVO, SOV, VSO, and so on, languages. (English, for instance, belongs to the SVO language type.)