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No. 93: May-Jun 1994

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Why Snakes Have Forked Tongues

Laymen and scientists alike have wondered for millennia why some reptiles possess forked tongues. It seems that we may now have an answer:

Some variations of the forked-tongue theme among lizards and snakes
Some variations of the forked-tongue theme among lizards and snakes.

"Theory, anatomy, neural circuitry, function, and behavior now support a hypothesis of the forked tongue as a chemosensory edge-detector used to follow pheromone trails of prey and conspecifics [especially the opposite sex]. The ability to sample simultaneously two points along a chemical gradient provides the basis for the instantaneous assessment of trail location."

The framer of this hypothesis, K. Schwenk, adds that the forked tongue and, obviously, the muscles and neural circuitry to use it properly, have evolved independently at least twice, possibly four times.

(Schwenk, Kurt; "Why Snakes Have Forked Tongues," Science, 263:1573, 1994.)

Comments . One can compare the forked tongue to binocular vision. Both require the parallel evolution of impressive infrastructures of data processing "equipment."

From Science Frontiers #93, MAY-JUN 1994. 1994-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:


  • "A sourcebook of unexplained phenomena is therefore a valuable addition to a collection of scientific literature. William R. Corliss has provided this in the past with his source books of scientific anomalies in several subjects, and now he has provided it for astronomy. He has done an excellent job of collecting and editing a large amount of material, taken in part from scientific journals and in part from scientific reporting in the popular or semi-scientific press." -- "The Mysterious Universe: A Handbook of Astronomical Anomalies", reviwed by Thomas Gold, Cornell University, in Icarus, vol.41, 1980

  • "An interesting, systematic presentation of unusual weather [..] This book is recommended for a general audience" --"Corliss, William R., Tornados, Dark Days, Anomalous Precipitation, and Related Weather Phenomena, Sourcebook Project, 1983.", revieweed in Choice, September 1983
  • "..the science is necessarily somewhat speculative, but Corliss's symthesis is based on reputable sources." -- "Corliss, William R. (Compiler). Lightning, Auroras, Nocturnal Lights, and Related Luminous Phenomena" reviwed by Joseph M. Moran, Univ. of Wisconsin in Science Books and Films, Sep/Oct 1983

  • "Before opening the book, I set certain standards that a volume which treads into dangerous grounds grounds like this must meet. The author scrupulously met, or even exceeded those standards. Each phenomenon is exhaustively documented, with references to scientific journals [..] and extensive quotations" -- "Book Review: The moon and planets: a catalog of astronomical anomalies", The Sourcebook Project, 1985., Corliss, W. R., Journal of the Royal Astronomical Society of Canada, Vol. 81, no. 1 (1987), p. 24., 02/1987