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A forked tongue is a tongue split into two distinct tines at the tip; this is a feature common to many species of reptiles. Reptiles smell using the tip of their tongue, and a forked tongue allows them to sense from which direction a smell is coming. Sensing from both sides of the head and following trails based on chemical cues is called tropotaxis.〔Schwenk, K. 1994. Why snakes have forked tongues. Science 263:1573-1577.〕 It is unclear whether forked-tongued reptiles can actually follow trails or if this is just a hypothesis.〔Kubie, J. L., and M. Halpern. 1979. Chemical senses involved in garter snake prey trailing. Journal of Comparative and Physiological Psychology 93:648-667.〕〔Waters, R. M. 1993, Odorizedair current trailing by garter snakes, Thamnophis sirtalis. Brain Behavior Evolution 41:219-223.〕〔Parker, M. R., B. A. Young, and K. V. Kardong. 2008. The forked tongue and edge detection in snakes (Crotalus oreganus): an experimental test. Journal of Comparative Psychology 122:35-40.〕 Forked tongues have evolved in these Squamate reptiles (lizards and snakes) for various purposes. The advantage to having a forked tongue is that more surface area is available for the chemicals to contact and the potential for tropotaxis.〔Cooper, W. E. 1995a. Evolution and function of lingual shape in lizards, with emphasis on elongation, extensibility, and chemical sampling. Journal of Chemical Ecology 21:477-505.〕 The tongue is flicked out of the mouth regularly to sample the chemical environment. This form of chemical sampling allows these animals to sense non-volatile chemicals, which cannot be detected by simply using the olfactory system.〔Baxi, K. N., K. M. Dorries, and H. L. Eisthen. 2006. Is the vomeronasal organ system really specialized for detecting pheromones? Trends in Neurosciences 29:1-7.〕〔Shine, R., X. Bonnet, M. J. Elphick, and E. G. Barrott. 2004. A novel foraging mode in snakes: browsing by the sea snake Emydocephalus annulatus (Serpentes, Hydrophiidae). Functional Ecology 18:16-24.〕〔Schwenk, K. 1995. Of tongues and noses, chemoreception in lizards and snakes. Trends in Ecology & Evolution 10:7-12.〕 This increased ability to sense chemicals has allowed for heightened abilities to identify prey, recognize kin, choose mates, locate shelters, follow trails, and more.〔Schwenk, K. 1995. Of tongues and noses, chemoreception in lizards and snakes. Trends in Ecology & Evolution 10:7-12.〕 Forked tongues have evolved multiple times in Squamates. It is unclear, based on the morphological and genetic evidence, where the exact points of change are from a notched tongue to a forked tongue, but it is believed that the change has happened two to four times.〔Schwenk, K. 1994. Why snakes have forked tongues. Science 263:1573-1577.〕〔Townsend, T. M., A. Larson, E. Louis, and J. R. Macey. 2004. Molecular phylogenetics of Squamata: the position of snakes, Amphisbaenians, and Dibamids, and the root of the Squamate tree. Systematic Biology 53:735-757.〕 A common behavioral characteristic that has evolved in those with forked tongues is that they tend to be wide foragers.〔Schwenk, K. 1994. Why snakes have forked tongues. Science 263:1573-1577〕〔Cooper, W. E. 1995b. Foraging mode, prey chemical discrimination, and phylogeny in lizards. Animal Behaviour 50:1709-1709.〕 Hummingbirds also have tongues that split at the tip. Galagos (bushbabies) have a secondary tongue, or sublingua, used for grooming, hidden under their first. ==Usage as First Nations cultural term== The phrase "speaks with a forked tongue" means to deliberately say one thing and mean another or, to be hypocritical, or act in a duplicitous manner. In the longstanding tradition of many Native American tribes, "speaking with a forked tongue" has meant lying, and a person was no longer considered worthy of trust, once he had been shown to "speak with a forked tongue". This phrase was also adopted by Americans around the time of the Revolution, and may be found in abundant references from the early 19th century — often reporting on American officers who sought to convince the tribal leaders with whom they negotiated that they "spoke with a straight and not with a forked tongue" (as for example, President Andrew Jackson told the Creek Nation in 1829〔''Niles' Register'', June 13, 1829〕). According to one 1859 account, the native proverb that the "white man spoke with a forked tongue" originated as a result of the French tactic of the 1690s, in their war with the Iroquois, of inviting their enemies to attend a Peace Conference, only to be slaughtered or captured.〔''Transactions of the New York State Agricultural Society'', Vol 19, 1859, p. 230.〕 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「forked tongue」の詳細全文を読む スポンサード リンク
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