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The origin of language in the human species has been the topic of scholarly discussions for several centuries. In spite of this, there is no consensus on the ultimate origin or age of human language. One problem makes the topic difficult to study: the lack of direct evidence. Consequently, scholars wishing to study the origins of language must draw inferences from other kinds of evidence such as the fossil record, archaeological evidence, contemporary language diversity, studies of language acquisition, and comparisons between human language and systems of communication existing among other animals (particularly other primates). Many argue that the origins of language probably relate closely to the origins of modern human behavior, but there is little agreement about the implications and directionality of this connection. This shortage of empirical evidence has led many scholars to regard the entire topic as unsuitable for serious study. In 1866, the Linguistic Society of Paris banned any existing or future debates on the subject, a prohibition which remained influential across much of the western world until late in the twentieth century.〔Stam, J. H. 1976. Inquiries into the origins of language. New York: Harper and Row, p. 255.〕 Today, there are numerous hypotheses about how, why, when, and where language might have emerged. Despite this, there is scarcely more agreement today than a hundred years ago, when Charles Darwin's theory of evolution by natural selection provoked a rash of armchair speculations on the topic.〔Müller, F. M. 1996 (). The theoretical stage, and the origin of language. Lecture 9 from Lectures on the Science of Language. Reprinted in R. Harris (ed.), The Origin of Language. Bristol: Thoemmes Press, pp. 7-41.〕 Since the early 1990s, however, a number of linguists, archaeologists, psychologists, anthropologists, and others have attempted to address with new methods what some consider "the hardest problem in science." ==Approaches== One can sub-divide approaches to the origin of language according to some underlying assumptions: * "Continuity theories" build on the idea that language exhibits so much complexity that one cannot imagine it simply appearing from nothing in its final form: it must therefore have evolved from earlier pre-linguistic systems among our primate ancestors. * "Discontinuity theories" take the opposite approach — that language as a unique trait cannot compare with anything found among non-humans and must therefore have appeared fairly suddenly during the course of human evolution. * Some theories see language mostly as an innate faculty - largely genetically encoded. * Other theories regard language as a mainly cultural system — learned through social interaction. Noam Chomsky, a prominent proponent of discontinuity theory, argues that a single chance mutation occurred in one individual in the order of 100,000 years ago, instantaneously installing the language faculty (a component of the mind-brain) in "perfect" or "near-perfect" form.〔Chomsky, N, 1996. ''Powers and Prospects. Reflections on human nature and the social order.'' London: Pluto Press, p 30.〕 According to this view, language's emergence resembled the formation of a crystal; with digital infinity as the seed crystal in a super-saturated primate brain, on the verge of blossoming into the human mind, by physical law, once evolution added a single small but crucial keystone.〔Chomsky, N. (2004). ''Language and Mind: Current thoughts on ancient problems.'' Part I & Part II. In Lyle Jenkins (ed.), ''Variation and Universals in Biolinguistics.'' Amsterdam: Elsevier, pp. 379-405.〕 It follows from this theory that language appeared rather suddenly within the history of human evolution. A majority of linguistic scholars hold continuity-based theories, but they vary in how they envision language development. Among those who see language as mostly innate, some — notably Steven Pinker — avoid speculating about specific precursors in nonhuman primates, stressing simply that the language faculty must have evolved in the usual gradual way.〔 〕 Others in this intellectual camp — notably Ib Ulbæk〔 — hold that language evolved not from primate communication but from primate cognition, which is significantly more complex. Those who see language as a socially learned tool of communication, such as Michael Tomasello, see it developing from the cognitively controlled aspects of primate communication, these being mostly gestural as opposed to vocal. Where vocal precursors are concerned, many continuity theorists envisage language evolving from early human capacities for song.〔''The Economist'', "(The evolution of language: Babel or babble? )", 16 April 2011, pp. 85-86.〕 Transcending the continuity-versus-discontinuity divide, some scholars view the emergence of language as the consequence of some kind of social transformation that, by generating unprecedented levels of public trust, liberated a genetic potential for linguistic creativity that had previously lain dormant. "Ritual/speech coevolution theory" exemplifies this approach. Scholars in this intellectual camp point to the fact that even chimpanzees and bonobos have latent symbolic capacities that they rarely - if ever - use in the wild. Objecting to the sudden mutation idea, these authors argue that even if a chance mutation were to install a language organ in an evolving bipedal primate, it would be adaptively useless under all known primate social conditions. A very specific social structure — one capable of upholding unusually high levels of public accountability and trust — must have evolved before or concurrently with language to make reliance on "cheap signals" (words) an evolutionarily stable strategy. Because the emergence of language lies so far back in human prehistory, the relevant developments have left no direct historical traces; neither can comparable processes be observed today. Despite this, the emergence of new sign languages in modern times — Nicaraguan Sign Language, for example — may potentially offer insights into the developmental stages and creative processes necessarily involved.〔Kegl, J., A. Senghas and M. Coppola (1998). Creation through Contact: Sign language emergence and sign language change in Nicaragua. In M. DeGraff (ed.), ''Language Creation and Change: Creolization, Diachrony and Development.'' Cambridge, MA: MIT Press.〕 Another approach inspects early human fossils, looking for traces of physical adaptation to language use.〔Lieberman, P. and E. S. Crelin (1971). On the speech of Neandertal Man. Linguistic Inquiry 2: 203-22.〕 In some cases, when the DNA of extinct humans can be recovered, the presence or absence of supposedly language-relevant genes — FOXP2, for example — may prove informative. Another approach, this time archaeological, involves invoking symbolic behavior (such as repeated ritual activity) that may leave an archaeological trace — such as mining and modifying ochre pigments for body-painting — while developing theoretical arguments to justify inferences from symbolism in general to language in particular. The time range for the evolution of language and/or its anatomical prerequisites extends, at least in principle, from the phylogenetic divergence of ''Homo'' (2.3 to 2.4 million years ago) from ''Pan'' (5 to 6 million years ago) to the emergence of full behavioral modernity some 150,000 - 50,000 years ago. Few dispute that ''Australopithecus'' probably lacked vocal communication significantly more sophisticated than that of great apes in general, but scholarly opinions vary as to the developments since the appearance of ''Homo'' some 2.5 million years ago. Some scholars assume the development of primitive language-like systems (proto-language) as early as ''Homo habilis'', while others place the development of symbolic communication only with ''Homo erectus'' (1.8 million years ago) or with ''Homo heidelbergensis'' (0.6 million years ago) and the development of language proper with ''Homo sapiens,'' currently estimated at less than 200,000 years ago. Using statistical methods to estimate the time required to achieve the current spread and diversity in modern languages, Johanna Nichols — a linguist at the University of California, Berkeley — argued in 1998 that vocal languages must have begun diversifying in our species at least 100,000 years ago.〔Johanna Nichols, 1998. The origin and dispersal of languages: Linguistic evidence. In Nina Jablonski and Leslie C. Aiello, eds., ''The Origin and Diversification of Language,'' pp. 127-70. (Memoirs of the California Academy of Sciences, 24.) San Francisco: California Academy of Sciences.〕 A further study by Q. D. Atkinson 〔 suggests that successive population bottlenecks occurred as our African ancestors migrated to other areas, leading to a decrease in genetic and phenotypic diversity. Atkinson argues that these bottlenecks also affected culture and language, suggesting that the further away a particular language is from Africa, the fewer phonemes it contains. By way of evidence, Atkinson claims that today's African languages tend to have relatively large numbers of phonemes, whereas languages from areas in Oceania (the last place to which humans migrated), have relatively few. Relying heavily on Atkinson's work, a subsequent study has explored the rate at which phonemes develop naturally, comparing this rate to some of Africa’s oldest languages. The results suggest that language first evolved around 350,000-150,000 years ago, which is around the time when modern ''Homo sapiens'' evolved. Estimates of this kind are not universally accepted but genetic, archaeological, palaeontological and much other evidence has led to a near-consensus that language probably emerged somewhere in sub-Saharan Africa during the Middle Stone Age, roughly contemporaneous with the speciation of ''Homo sapiens.''〔 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Origin of language」の詳細全文を読む スポンサード リンク
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