Quadrupedalism (from Latin, meaning "four legs") is a form of land animal locomotion using four legs. The majority of walking animals are quadrupeds, including mammals such as cattle and cats, and reptiles, like lizards. Birds, humans, insects, crustaceans and snakes are not quadrupeds. There are some exceptions, for example among the insects the praying mantis is a quadruped. A few birds may use quadrupedal movement in some circumstances, for example the shoebill will sometimes use its wings to right itself after lunging at prey.

Quadrupeds and tetrapods

Not all four-limbed animals are quadrupeds. Although arms and wings are, in the evolutionary sense, modified legs, four-limbed animals are in fact classed as tetrapods – members of the taxonomic unit "Tetrapoda". These include all vertebrates with quadrupedal ancestors, including mammals, reptiles, amphibians, and birds. See Pierson v. Post, 3 Cai. R. 175, 2 Am. Dec. 264 (N.Y. 1805), read this case for common law knowledge of quadrupeds ferae naturae.

The distinction between quadrupeds and tetrapods is important in evolutionary biology, particularly in the context of bipeds, winged animals, and animals whose limbs have adapted to other roles (e.g. fins, in the case of cetaceans and pinnipeds). All of these animals are tetrapods, but none are quadrupeds. Even snakes, whose limbs have become entirely vestigial, are nevertheless tetrapods.

Quadrupedalism in humans

In July 2005, in rural Turkey, scientists discovered five Kurdish siblings who had learned to walk naturally on their hands and feet. Unlike chimpanzees, who ambulate on their knuckles, the Turkish siblings (ranging from 18 to 34 years old) walked on their palms, allowing them to preserve the dexterity of their fingers. Calluses found on their hands make the possibility of a hoax unlikely. Another similar case has been reported in Chile, but the case is still being investigated and reports are not released as of March 22, 2006.

The discovery of the family has provided scientists a unique view into human evolutionary history. Nicholas Humphrey, a researcher from the London School of Economics, has [http://eprints.lse.ac.uk/archive/00000463/01/CPNSS2.pdf suggested] and colleagues have argued that their gait is due to two rare phenomena coming together. First, instead of initially crawling as infants on their knees, they started off learning to move around with a “bear crawl” on their feet. Second, due to their congenital brain impairment, they found balancing on two legs difficult. Because this, their motor development was channelled into turning their bear crawl into a substitute for bipedality.

Other scientists, such as Stefan Mundlos of the Max Planck Institute, believe that the family's unusual gait may result from a genetic abnormality. Mundlos has found a region on chromosome 17 that might be responsible for human bipedalism.

Quadrupedal Movement for Exercise

External links

* [http://news.bbc.co.uk/2/hi/science/nature/4782492.stm Family may provide evolution clue] - BBC News
* [http://www.allfoursfamily.com/index.htm A website devoted to the above family that walks quadrupedally]
* [http://www.youtube.com/watch?v=S5YqI_PhxJ4&mode=related&search= Basic training for quadrupedal locomotion]

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Look at other dictionaries:

  • Quadruped — Quad ru*ped, n. (Zo[ o]l.) An animal having four feet, as most mammals and reptiles; often restricted to the mammals. [1913 Webster] …   The Collaborative International Dictionary of English

  • Quadruped — Quad ru*ped, a. [L. quadrupes, pedis; quattuor four + pes, pedis, a foot: cf. F. quadrup[ e]de. See {Quadrate}, and {Foot}.] Having four feet. [1913 Webster] …   The Collaborative International Dictionary of English

  • quadruped — quadruped, ausschließliche oder überwiegende Fortbewegungsweise auf vier Extremitäten bei Wirbeltieren (Amphibien, viele Reptilien, die meisten Säuger) …   Deutsch wörterbuch der biologie

  • quadruped — (n.) 1610s (implied in quadrupedal), from Fr. quadrupède, from M.Fr., from L. quadrupes (gen. quadrupedis) four footed, a four footed animal, from quadri four (see QUADRI (Cf. quadri )) + pes foot (see FOOT (Cf. foot)). The adjective is attested… …   Etymology dictionary

  • quadruped — ► NOUN ▪ an animal which has four feet, especially a mammal. DERIVATIVES quadrupedal adjective. ORIGIN from Latin quadru four + pes foot …   English terms dictionary

  • quadruped — [kwä′dro͞o ped΄, kwä′drooped΄, kwä′drəped΄] n. [L quadrupes (gen. quadrupedis) < quadru (used for quadri ,QUADRI , esp. before p), four + pes,FOOT] an animal, esp. a mammal, with four feet adj. having four feet quadrupedal [kwä dro͞o′pə dəl;… …   English World dictionary

  • quadruped — noun Etymology: Latin quadruped , quadrupes, from quadruped , quadrupes, adjective, having four feet, from quadri + ped , pes foot more at foot Date: 1646 an animal having four feet • quadruped adjective • quadrupedal adjective …   New Collegiate Dictionary

  • quadruped — UK [ˈkwɒdrʊped] / US [ˈkwɑdrəˌped] noun [countable] Word forms quadruped : singular quadruped plural quadrupeds biology an animal that walks on four legs …   English dictionary

  • quadruped — quadrupedal /kwo drooh pi dl, kwod roo ped l/, adj. quadrupedism, n. /kwod roo ped /, adj. 1. four footed. n. 2. an animal, esp. a mammal, having four feet. [1640 50; < L quadruped (s. of quadrupes), equiv. to quadru QUADRU + ped PED] * * * …   Universalium

  • quadruped — [[t]kwɒ̱drʊped[/t]] quadrupeds N COUNT A quadruped is any animal with four legs. [FORMAL] …   English dictionary

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