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In the philosophy of language a natural language (or ordinary language) is any language which arises in an unpremeditated fashion as the result of the innate facility for language possessed by the human intellect. A natural language is typically used for communication and may be spoken signed or written. Natural language is distinguished from constructed languages and formal languages such as computer-programming languages or the "languages" used in the study of formal logic especially mathematical logic. Contents 1 Defining natural language 2 Native language learning 3 Origins of natural language 4 Linguistic diversity 5 Taxonomy 5.1 Genetic classification 5.2 Typological classification 5.3 Areal classification 6 Controlled languages 7 Constructed languages and international auxiliary languages 8 Modalities 8.1 Sign languages 8.2 Written languages 9 See also 10 Notes 11 References Defining natural language

Though the exact definition varies between scholars natural language can broadly be defined in contrast on the one hand to artificial or constructed languages such as computer programming languages like Python and international auxiliary languages like Esperanto and on the other hand to other communication systems in nature such as the waggle dance of bees. Although there are a variety of natural languages any cognitively normal human infant is able to learn any natural language. By comparing the different natural languages scholars hope to learn something about the nature of human intelligence and the innate biases and constraints that shape natural language.

Linguists have an incomplete understanding of all aspects of the rules underlying natural languages and these rules are therefore objects of study. The understanding of natural languages reveals much about not only how language works (in terms of syntax semantics phonetics phonology etc.) but also about how the human mind and the human brain process language. In linguistic terms natural language only applies to a language that has developed naturally and the study of natural language primarily involves native (first language) speakers.

The theory of universal grammar proposes that all natural languages have certain underlying rules which constrain the structure of the specific grammar for any given language.

While grammarians writers of dictionaries and language policy-makers all have a certain influence on the evolution of language their ability to influence what people think they ought to say is distinct from what people actually say. The term natural language refers to actual linguistic behavior and is aligned with descriptive linguistics rather than linguistic prescription. Thus non-standard language varieties (such as African American Vernacular English) are considered to be natural while standard language varieties (such as Standard American English) which are more prescribed can be considered to be at least somewhat artificial or constructed. Native language learning Main article: Language acquisition The learning of one's own native language typically that of one's parents normally occurs spontaneously in early human childhood and is biologically driven. A crucial role of this process is the ability of humans from an early age to engage in speech repetition and so quickly acquire a spoken vocabulary from the pronunciation of words spoken around them. This together with other aspects of speech involves the neural activity of parts of the human brain such as the Wernicke's and Broca's areas. There are approximately 7000 current human languages and many if not most seem to share certain properties leading to the belief in the existence of Universal Grammar as shown by generative grammar studies pioneered by the work of Noam Chomsky. Recently it has been demonstrated 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 complex verbal structures (but not simple ones) of those languages that meet the Universal Grammar requirements.12 Origins of natural language Main article: Origin of language There is disagreement among anthropologists on when language was first used by humans (or their ancestors). Estimates range from about two million (2000000) years ago during the time of Homo habilis to as recently as forty thousand (40000) years ago during the time of Cro-Magnon man. However recent evidence suggests modern human language was invented or evolved in Africa prior to the dispersal of humans from Africa around 50000 years ago. Since all people including the most isolated indigenous groups such as the Andamanese or the Tasmanian aboriginals possess language then it was presumedly present in the ancestral populations in Africa before the human population split into various groups to inhabit the rest of the world.34 Linguistic diversity See also: Multilingualism Together the eight countries in red contain more than 50% of the world's languages. The areas in blue are the most linguistically diverse in the world. As of 2009 SIL Ethnologue catalogued 6909 living human languages.5 A "living language" is simply one which is in wide use as a primary form of communication by a specific group of living people. The exact number of known living languages will vary from 5000 to 10000 depending generally on the precision of one's definition of "language" and in particular on how one classifies dialects. There are also many dead and distinct from dead extinct languages. There is no clear distinction between a language and a dialect notwithstanding linguist Max Weinreich'scitation needed 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. It is probably impossible to accurately enumerate the living languages because our worldwide knowledge is incomplete and it is a "moving target" as explained in greater detail by the Ethnologue's Introduction p. 7 - 8. With the 15th edition the 103 newly added languages are not new but reclassified due to refinements in the definition of language. Although widely considered an encyclopedia the Ethnologue actually presents itself as an incomplete catalog including only named languages that its editors are able to document. With each edition the number of catalogued languages has grown. Beginning with the 14th edition (2000) an attempt was made to include all known living languages. SIL used an internal 3-letter code fashioned after airport codes to identify languages. This was the precursor to the modern ISO 639-3 standard to which SIL contributed. The standard allows for over 14000 languages. In turn the 15th edition was revised to conform to the pending ISO 639-3 standard. Of the catalogued languages 497 have been flagged as "nearly extinct" due to trends in their usage. Per the 15th edition 6912 living languages are shared by over 5.7 billion speakers. (p. 15) Some major limitations in the accuracy of Ethnologue's speaker population data should however be noted.67 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 languageswhich is based on genetic relatedness of languages paying attention to the internal structure of languages (grammar) results in a typological classification of languageswhich 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 typologicalto linguistic typology. See also Taxonomy and Taxonomic classification for the general idea of classification and taxonomies. Genetic classification Main article: Language family 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 Main article: Linguistic typology 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). The shared features of languages of one type ( from one typological class) may have arisen completely independently. (Compare with analogy in biology.) Their cooccurence might be due to the universal laws governing the structure of natural languageslanguage universals. Areal classification Main article: Areal feature The following language groupings can serve as some linguistically significant examples of areal linguistic units or sprachbunds: Balkan linguistic union or the bigger group of European languages; Caucasian languages; East Asian languages. Although the members of each group are not closely genetically related there is a reason for them to share similar features namely: their speakers have been in contact for a long time within a common community and the languages converged in the course of the history. These are called "areal features". One should be careful about the underlying classification principle for groups of languages which have apparently a geographical name: besides areal linguistic units the taxa of the genetic classification (language families) are often given names which themselves or parts of which refer to geographical areas. Controlled languages Main article: Controlled natural language Controlled natural languages are subsets of natural languages whose grammars and dictionaries have been restricted in order to reduce or eliminate both ambiguity and complexity (for instance by cutting down on rarely used superlative or adverbial forms or irregular verbs). The purpose behind the development and implementation of a controlled natural language typically is to aid non-native speakers of a natural language in understanding it or to ease computer processing of a natural language. An example of a widely used controlled natural language is Simplified English which was originally developed for aerospace industry maintenance manuals. Constructed languages and international auxiliary languages Main article: Constructed language Main article: International auxiliary language Constructed international auxiliary languages such as Esperanto and Interlingua (even those that have native speakers) are not generally considered natural languages.8 The problem is that other languages have been used to communicate and evolve in a natural way while Esperanto was selectively designed by L.L. Zamenhof from natural languages not grown from the natural fluctuations in vocabulary and syntax. Nor has Esperanto been naturally "standardized" by children's natural tendency to correct for illogical grammar structures in their parents' language which can be seen in the development of pidgin languages into creole languages (as explained by Steven Pinker in The Language Instinct). The possible exception to this are true native speakers of such languages.9 More substantive basis for this designation is that the vocabulary grammar and orthography of Interlingua are natural; they have been standardized and presented by a linguistic research body but they predated it and are not themselves considered a product of human invention.10 Most experts however consider Interlingua to be naturalistic rather than natural.11 Latino Sine Flexione a second naturalistic auxiliary language is also naturalistic in content but is no longer widely spoken.12 Modalities Natural language manifests itself in modalities other than speech. Sign languages A sign language is a language which conveys meaning through visual rather than acoustic patternssimultaneously combining hand shapes orientation and movement of the hands arms or body and facial expressions to express a speaker's thoughts. Sign languages are natural languages which have developed in Deaf communities which can include interpreters and friends and families of deaf people as well as people who are deaf or hard of hearing themselves. In contrast a manually coded language (or signed spoken language) is a constructed sign system combining elements of a sign language and a spoken language. For example Signed Exact English (SEE) did not develop naturally in any population but was "created by a committee of individuals".13 Written languages Main article: Written language In a sense written language should be distinguished from natural language. Until recently in the developed world it was common for many people to be fluent in spoken or signed languages and yet remain illiterate; this is still the case in poor countries today. Furthermore natural language acquisition during childhood is largely spontaneous while literacy must usually be intentionally acquired.14 See also Language Natural language processing (NLP) Universal grammar LGML Linguistics Markup Language Controlled vocabulary Notes A. Moro M. Tettamanti D. Perani C. Donati S. F. Cappa F. Fazio Syntax and the brain: disentangling grammar by selective anomalies NeuroImage 13 January 2001 Academic Press Chicago pp. 110-118 Musso M. Moro A. Glauche. V. Rijntjes M. Reichenbach J. Bchel C. Weiller C. Brocas area and the language instinct Nature neuroscience 2003 vol. 6 pp. 774-781. Early Voices: The Leap to Language nytimes article by Nicholas Wade 1 "Ethnologue: Languages of the World Fifteenth edition" accessed 28 June 2007 ISBN 1 55671 159 X Paolillo J.C. & Das A.: "Evaluating Language Statistics: The Ethnologue and Beyond". 2006 Gerrand P.: "Estimating Linguistic Diversity on the Internet: A Taxonomy to Avoid Pitfalls and Paradoxes" JCMC 2007 Gopsill F. P. "A historical overview of international languages". In International languages: A matter for Interlingua. Sheffield England: British Interlingua Society 1990. Proponents contend that there are 200-2000 native speakers of Esperanto. Gode Alexander Interlingua-English: A dictionary of the international language. New York: Storm Publishers 1951. (Original edition) Gopsill F. P. "A historical overview of international languages". In International languages: A matter for Interlingua. Sheffield England: British Interlingua Society 1990. Gopsill F. P. "Naturalistic international languages". In International languages: A matter for Interlingua. Sheffield England: British Interlingua Society 1990. Emmorey Karen. Language cognition and the brain: insights from sign language research (2001) p. 11. Pinker Steven. 1994. The Language Instinct References ter Meulen Alice 2001 "Logic and Natural Language" in Goble Lou ed. The Blackwell Guide to Philosophical Logic. Blackwell.