NationMaster - Encyclopedia: Bipedalism

Bipedalism is standing, or moving for example by walking, running, or hopping, on two appendages (typically legs though it can also include hand walking). An animal or machine that usually moves in a bipedal manner is known as a biped (/'baɪ.pɛd/), meaning "two feet" (Latin bi = two + ped = foot). This article or section is in need of attention from an expert on the subject. ... This article does not cite any references or sources. ... For other uses, see Running (disambiguation). ... Look up Jumping in Wiktionary, the free dictionary. ... An appendage is, in general, an external body part that projects from the body, or a natural prolongation or projection from a part of any organism. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Hand walking is an unusual form of locomotion, in which the walker moves primarily using their hands. ... For other uses, see Animal (disambiguation). ... This article is about devices that perform tasks. ... For other uses, see Latin (disambiguation). ...

Image File history File links Strauss_m_Tanzania. ... Image File history File links Strauss_m_Tanzania. ... Binomial name Linnaeus, 1758 The present-day distribution of Ostriches. ... Nude Man Running - Edward Muybridge This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Nude Man Running - Edward Muybridge This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... The Horse in Motion Eadweard Muybridge (April 9, 1830 – May 8, 1904) was a British-born photographer, known primarily for his early use of multiple cameras to capture motion. ...

Overview

Types of bipedal movement

Standing is a human position in which the body constantly is in an orthostatic state. ... This article does not cite any references or sources. ... For other uses, see Running (disambiguation). ... Look up Jumping in Wiktionary, the free dictionary. ...

Bipedal animals

Bipedalism, involving the exclusive use of two legs for locomotion, has evolved multiple times in vertebrates. In reptiles, it evolved once with the thecodonts, anscestors to crocodiles, birds and dinosaurs, and once with the lizards such as the zebra-tailed lizard. Within mammals, exclusive bipedalism has evolved three times, with the kangaroos, kangaroo mice and humans.^[1] Within these groups there is still variations in locomotion - in large birds and humans locomotion occurs through walking by alternating legs. In comparison, kangaroos, smaller birds and kangaroo mice move through hopping on both legs simultaneously. This article does not cite any references or sources. ... Reptilia redirects here. ... Thecodont (socket-toothed reptile), is a catch-all (paraphyletic) group, now considered an obsolete term, that was formerly used to describe a group of the earliest archosaurs that lived during the Permian and Triassic periods. ... For other uses, see Crocodile (disambiguation). ... For other uses, see Bird (disambiguation). ... Orders & Suborders Saurischia Sauropodomorpha Theropoda Ornithischia Thyreophora Ornithopoda Marginocephalia Dinosaurs were vertebrate animals that dominated the terrestrial ecosystem for over 160 million years, first appearing approximately 230 million years ago. ... lizards are pink and become very aggressive when they see other females. ... Species See text. ... Subclasses & Infraclasses Subclass â€ Allotheria* Subclass Prototheria Subclass Theria Infraclass â€ Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the presence of sweat glands, including those that produce milk, and by the presence of: hair, three middle ear bones used in hearing, and a neocortex... Species Macropus rufus Macropus giganteus Macropus fuliginosus Macropus antilopinus A kangaroo is a marsupial from the family Macropodidae (macropods, meaning large foot). In common use the term is used to describe the largest species from this family, the Red Kangaroo, the Antilopine Kangaroo, and the Eastern and Western Grey Kangaroo... Species Microdipodops megacephalus Microdipodops palllidus A kangaroo mouse is either one of the two species of jumping mouse (genus Microdipodops) native to the deserts of the Southwestern United States, predominately found in the state of Nevada. ... This article is about modern humans. ... This article does not cite any references or sources. ...

Dinosaurs and their descendants

All dinosaurs are believed to be descended from a fully bipedal ancestor, perhaps similar to Eoraptor. It is believe that maniraptors were able to reach speeds of up to 65 km/h moving bipedally, comparable to their large, flightless-bird descendants such as the ostrich. Bipedal movement also re-evolved in a number of other dinosaur lineages such as the iguanodons. Some extinct members of the crocodilian line, a sister group to the dinosaurs and birds, also evolved bipedal forms - a crocodile relative from the triassic, Effigia okeeffeae, was believed to be bipedal.^[2] Binomial name Sereno et al, 1993 Eoraptor was one of the worlds earliest dinosaurs. ... Maniraptora is a group used in biological classification to cover the birds and the dinosaurs that were related to them. ... Binomial name Linnaeus, 1758 The present-day distribution of Ostriches. ... Orders & Suborders Saurischia Sauropodomorpha Theropoda Ornithischia Thyreophora Ornithopoda Marginocephalia Dinosaurs were vertebrate animals that dominated the terrestrial ecosystem for over 160 million years, first appearing approximately 230 million years ago. ... Species (Boulenger, 1881) (neotype) (Holl, 1829) nom. ... Suborders Eusuchia Protosuchia â€ Mesosuchia â€ Sebecosuchia â€ Thalattosuchia â€ Crocodilia is an order of large reptiles that scientists believe branched off from class Reptilia about 220 million years ago. ... For other uses, see Crocodile (disambiguation). ... The Triassic is a geologic period that extends from about 251 Â± 0. ... Effigia okeeffeae was an archosaur that lived in what is now New Mexico. ...

Mammals

Bipedal movement is less common among mammals, most of which are quadrupedal. The largest mammalian group using bipedal movement are the kangaroos and their relatives, which move via hopping. Other mammals also move via hopping, such as the kangaroo rat, springhare and certain primates such as the sifaka and sportive lemur. Possibly the only mammals other than humans that commonly move bipedally by an alternating gait rather than hopping are gibbons when on the ground, and giant pangolins. Subclasses & Infraclasses Subclass â€ Allotheria* Subclass Prototheria Subclass Theria Infraclass â€ Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the presence of sweat glands, including those that produce milk, and by the presence of: hair, three middle ear bones used in hearing, and a neocortex... The Zebra is an example of a quadruped. ... Species Macropus rufus Macropus giganteus Macropus fuliginosus Macropus antilopinus A kangaroo is a marsupial from the family Macropodidae (macropods, meaning large foot). In common use the term is used to describe the largest species from this family, the Red Kangaroo, the Antilopine Kangaroo, and the Eastern and Western Grey Kangaroo... Species 22, see text Kangaroo rats, genus Dipodomys, are small rodents native to North America. ... Binomial name Pedetes capensis (Forster, 1778) The Springhare (Pedetes capensis), or Springhaas, is not actually a hare, but a member of the order Rodentia; it is the only species in its family Pedetidae and in the genus Pedetes. ... Type Species Propithecus diadema Bennett, 1832 Species Propithecus diadema Propithecus candidus Propithecus edwardsi Propithecus perrieri Propithecus tattersalli Propithecus verreauxi Propithecus coquereli Propithecus deckenii Sifakas are a genus (Propithecus) from the primate family Indriidae. ... Type Species Lepilemur mustelinus I. Geoffroy Species Lepilemur aeeclis Lepilemur ankaranensis Lepilemur dorsalis Lepilemur edwardsi Lepilemur leucopus Lepilemur microdon Lepilemur mustelinus Lepilemur randrianasoli Lepilemur ruficaudatus Lepilemur sahamalazensis Lepilemur septentrionalis The sportive lemurs are the medium sized primates that make up the Lepilemuridae family. ... Genera Hylobates Hoolock Nomascus Symphalangus Gibbons are the small apes that are grouped in the family Hylobatidae. ... Binomial name Illiger, 1815 The Giant Pangolin (Manis gigantea) is a pangolin species. ...

Limited bipedalism in mammals

Other mammals engage in limited, non-locomotory, bipedalism. The bonobo and proboscis monkey both live in forests that are often flooded and will wade through water in a bipedal stance; along with other primates, they will also also walk or stand bipedely on land, though generally for short periods. Two captive primates, the macaque Natasha^[3] and chimp Oliver both move bipedally. Natasha switched to exclusive bipedalism after an illness, while Oliver reverted to knuckle-walking after developing arthritis. A number of other animals, such as rats, racoons, and beavers will squat on their hindlegs in order to manipulate some objects but revert to four limbs when moving (the beaver may also move bipedally if transporting wood for their dams). Bears will fight in a bipedal stance in order to use their forelegs as weapons. Ground squirrels and meerkats will stand on hind legs to survey their surroundings, but will not walk bipedally. Dogs will stand on their hind legs if trained to do so, and some can even walk for a trick or in the case of birth defect destroying their forelimbs.^[4] The gerenuk antelope stands on its hind legs while eating from trees, as did the extinct giant ground sloth and chalicotheres. The spotted skunk will also use limited bipedalism when threatened, rearing up while facing the attacker so its anal glands, capable of spraying an offensive oil, face its attacker. For other uses, see Bonobo (disambiguation). ... Binomial name Wurmb, 1787 The Proboscis Monkey, Nasalis larvatus also known as Long-nosed Monkey is a reddish-brown arboreal Old World monkey. ... Natasha is a black macaque at the Safari Park zoo near Tel Aviv, Israel. ... Oliver, the Humanzee. Oliver was a performing Common Chimpanzee who was once promoted as a missing link, or a Humanzee (a human-chimp hybrid). ... Gorillas knuckle-walk using both their legs and their long arms (putting pressure on their knuckles, with the fingers rolled into the hand). ... Species 50 species; see text *Several subfamilies of Muroids include animals called rats. ... Racoon is a Dutch rock band, formed in 1997. ... Species C. canadensis C. fiber Beavers are semi-aquatic rodents native to North America and Europe. ... Species C. canadensis C. fiber Beavers are semi-aquatic rodents native to North America and Europe. ... For other uses, see Bear (disambiguation). ... Genera Ammospermophilus Spermophilus Cynomys Marmota Tamias Sciurotamias The ground squirrels are all members of the Sciuridae most closely related to the genus Marmota and included in the tribe Marmotini. ... Binomial name (Schreber, 1776) Meerkat range The meerkat or suricate Suricata suricatta is a small mammal and a member of the mongoose family. ... Trinomial name Canis lupus familiaris The dog (Canis lupus familiaris) is a domestic subspecies of the wolf, a mammal of the Canidae family of the order Carnivora. ... Dog training is the process of teaching a dog (Canis lupus familiaris) to perform certain behaviors under various circumstances and in certain roles on command. ... Binomial name Litocranius walleri (Brooke, 1878) The Gerenuk (Litocranius walleri) is an antelope-like animal, closely related to the gazelle, found in East Africa. ... Megatheriinae were a subfamily of elephant-sized ground sloths that lived from 2 million to 8,000 years ago. ... Chalicotheres were a group of perissodactyl mammals that lived from 45 to 3. ... Species Spilogale gracilis Merriam, 1890 Spilogale putorius (Linnaeus, 1758) Spilogale pygmaea Thomas, 1898 Spilogale angustifrons Howell, 1902 The Spotted Skunks are three species of Skunk in the genus Spilogale. ... Illustration showing the location of the anal glands in a typical dog. ...

Limited bipedalism in non-mammals

Bipedalism is unknown among the amphibians. Among the non-archosaur reptiles bipedalism is rare, but it is found in the 'reared-up' running of certain lizards and monitor lizards will also temporarily adopt bipedalism while fighting.^[5] One genus of basilisk lizard can run bipedally across the surface of water for some distance. Bipedalism in the form of reared-up running can also be found in cockroaches, but is otherwise unknown in arthropods. Bipedalism is virtually solely found in terrestrial animals, though at least two types of octopus walk bipedally on the sea floor using two of their arms, allowing the remaining arms to be used to camouflage the octopus as a mat of algae or a floating coconut.^[6] For other uses, see Amphibian (disambiguation). ... Clades Crurotarsi Aetosauria Crocodilia (crocodiles) Phytosauria Rauisuchia Ornithodira Aves (birds) Dinosauria Pterosauria Archosaurs (Greek for ruling lizards) are a group of diapsid reptiles that is represented today by birds and crocodiles and which also included the dinosaurs. ... Reptilia redirects here. ... lizards are pink and become very aggressive when they see other females. ... Species Many, see text. ... Species Basiliscus basiliscus Basiliscus galeritus Basiliscus plumifrons Basiliscus vittatus Basiliscus is a genus of lizards that includes the basilisks. ... For other uses, see Cockroaches. ... Subphyla and Classes Subphylum Trilobitomorpha Trilobita - trilobites (extinct) Subphylum Chelicerata Arachnida - spiders,scorpions, etc. ... Terrestrial animals are animals that live predominantly or entirely on land, as compared with aquatic animals, which live predominantly or entirely in the water (e. ... For other uses, see Octopus (disambiguation). ...

Advantages

Limited and exclusive bipedalism can offer a species several advantages. Bipedalism raises the head; this allows a greater field of vision with improved detection of distant dangers or resources, access to deeper water for wading animals and allows the animals to reach higher food sources with their mouths. While upright, non-locomotory limbs become free for other uses, including manipulation (in primates and rodents), flight (in birds), digging (in giant pangolin), combat (in bears and the large monitor lizard) or camouflage (in certain species of octopus). Running speeds can be increased when an animal lacks a flexible backbone, though the maximum bipedal speed appears less fast than the maximum speed of quadrapedal movement with a flexible backbone - the ostrich reaches speeds of (65 km/h) and the red kangaroo (70 km/h), while the cheetah can exceed 100 km/h. A limb (from the Old English lim) is a jointed, or prehensile (as octopus tentacles or new world monkey tails), appendage of the human or animal body; a large or main branch of a tree; a representative, branch or member of a group or organization. ... Binomial name Linnaeus, 1758 The present-day distribution of Ostriches. ... Binomial name Desmarest, 1822 The Red Kangaroo (Macropus rufus) is the largest of all kangaroos and the largest surviving marsupial. ... This article is about the animal. ...

Evolution

Bipedalism has a number of adaptive advantages, and has evolved independently in a number of lineages.

Early reptiles and lizards

The first known biped is the bolosaurid Eudibamus cursoris whose fossils date from 290 million years ago.^[7]^[8] Its long hindlegs, short forelegs, and distinctive joints all suggest bipedalism. This may have given increased speed. The species was extinct before the dinosaurs appeared. The bolosaurids is an extinct group of anapsids from the Permian. ...

Independent of Eudibamus, some modern lizard species have developed the capacity to run on their hind legs for added speed.

Dinosaurs and birds

Bipedalism also developed independently among the dinosaurs. Dinosaurs diverged from their archosaur ancestors approximately 230 million years ago during the Middle to Late Triassic period, roughly 20 million years after the Permian-Triassic extinction event wiped out an estimated 95% of all life on Earth.^[9]^[10] Radiometric dating of fossils from the early dinosaur genus Eoraptor establishes its presence in the fossil record at this time. Paleontologists believe Eoraptor resembles the common ancestor of all dinosaurs;^[11] if this is true, its traits suggest that the first dinosaurs were small, bipedal predators.^[12] The discovery of primitive, dinosaur-like ornithodirans such as Marasuchus and Lagerpeton in Argentinian Middle Triassic strata supports this view; analysis of recovered fossils suggests that these animals were indeed small, bipedal predators. Clades Crurotarsi Aetosauria Crocodilia (crocodiles) Phytosauria Rauisuchia Ornithodira Aves (birds) Dinosauria Pterosauria Archosaurs (Greek for ruling lizards) are a group of diapsid reptiles that is represented today by birds and crocodiles and which also included the dinosaurs. ... The Triassic is a geologic period that extends from about 251 Â± 0. ... The Permian-Triassic (P-T or PT) extinction event, sometimes informally called the Great Dying, was an extinction event that occurred approximately 251 million years ago (mya), forming the boundary between the Permian and Triassic geologic periods. ... This article is about the tv programme Life on Earth. ... Radiometric dating (often called radioactive dating) is a technique used to date materials, based on a comparison between the observed abundance of particular naturally occurring radioactive isotopes and their known decay rates. ... For other uses, see Genus (disambiguation). ... Binomial name Sereno et al, 1993 Eoraptor was one of the worlds earliest dinosaurs. ... A group of organisms is said to have common descent if they have a common ancestor. ... Species Lagosuchus was a small archosaur from the mid-Triassic. ... Lagerpeton is the name given to a genus of reptile from the Ladinian (Middle Triassic). ... For other uses, see Argentina (disambiguation). ... The Middle Triassic (also known as Muschelkalk) is the second of three epochs of the Triassic period. ...

Mammals (excluding humans)

A number of mammals will adopt a bipedal stance in specific situations such as for feeding or fighting. A number of groups of extant mammals have independently evolved bipedalism as their main form of locomotion - for example humans, giant pangolins, and macropods. Humans, as their bipedalism has been extensively studied are documented in the next section. Macropods are believed to have evolved bipedal hopping only once in their evolution, at some time no later than 45 million years ago.^[13]

Humans

There are at least twelve distinct hypotheses as to how and why bipedalism evolved in humans, and also some debate as to when. Evidence points to bipedalism evolving before the expansion in human brain size. The different hypotheses are not necessarily mutually exclusive and a number of selective forces may have acted together to lead to human bipedalism.

Postural feeding hypothesis

The postural feeding hypothesis has been recently supported by Dr. Kevin Hunt, a professor at Indiana University. This theory asserts that chimpanzees were only bipedal when they ate. While on the ground, they would reach up for fruit hanging from small trees and while in trees, bipedalism was utilized by grabbing for an overhead branch. These bipedal movements may have evolved into regular habits because they were so convenient in obtaining food. Also, Hunt theorizes that these movements coevolved with chimpanzee arm-hanging, as this movement was very effective and efficient in harvesting food. When analyzing fossil anatomy, Australopithecus afarensis has very similar features of the hand and shoulder to the chimpanzee, which indicates hanging arms. Also, the Australopithecus hip and hind limb very clearly indicate bipedalism, but these fossils also indicate very inefficient locomotive movement when compared to humans. For this reason, Hunt argues that bipedalism evolved more as a terrestrial feeding posture than as a walking posture. As Hunt says, “A bipedal postural feeding adaptation may have been a preadaptation for the fully realized locomotor bipedalism apparent in Homo erectus.” A related hypothesis is that proto-humans learned upright posture not for picking fruit, as it is argued they would have stayed climbers if plucking fruit were all they were after, rather they learned to keep they head out of the water while searching for water plants, mollusca, and the like. Type species Simia troglodytes Blumenbach, 1775 distribution of Species Pan troglodytes Pan paniscus Chimpanzee, often shortened to chimp, is the common name for the two extant species of apes in the genus Pan. ... Binomial name Johanson & White, 1978 Australopithecus afarensis is an extinct hominid which lived between 3. ... For the song by Modest Mouse, see Sad Sappy Sucker. ... Human beings are defined variously in biological, spiritual, and cultural terms, or in combinations thereof. ...

Provisioning model

One of the most elaborate theories on the origin of bipedalism is the behavior model presented by C. Owen Lovejoy. Lovejoy theorizes that the evolution of bipedalism was a response to a monogamous society. As hominid males became monogamous, they would leave their families for the day in order to search for food. Once they found food for their family, the hominids would have to bring back the food, and the most effective way of doing this was through bipedalism. Some question whether early hominids really were monogamous though. Some evidence indicates that early hominids, which are proven to be bipedal, were polygamous. Among all monogamous primates, sexual dimorphism is mostly absent, but in Australopithecus afarensis males were found to be nearly twice the weight of females, an attribute scientists would expect in a polygamous species. Lastly, monogamous primates are highly territorial, but fossil evidence indicates that Australopithecus afarensis lived in large groups. This article is about evolution in biology. ... A hominid is any member of the biological family Hominidae (the great apes), including the extinct and extant humans, chimpanzees, gorillas, and orangutans. ... Female (left) and male Common Pheasant, illustrating the dramatic difference in both color and size, between the sexes Sexual dimorphism is the systematic difference in form between individuals of different sex in the same species. ...

Other behavioural models

There are a variety of ideas which promote a specific change in behaviour as the key driver for the evolution of hominid bipedalism. For example, Wescott (1967) and later Jablonski & Chaplin (1993) suggest that bipedal threat displays could have been the transitional behaviour which led to some groups of apes beginning to adopt bipedal postures more often. Others (e.g. Dart 1925) have offered the idea that the need for more vigilance against predators could have provided the initial motivation. Dawkins (e.g. 2004) has argued that it could have begun as a kind of fashion that just caught on and then escalated through sexual selection. And it has even been suggested (e.g. Tanner 1981:165) that male phallic display could have been the initial incentive. All these theories lack any observational data, and are in the category of "armchair" theories.

Thermoregulatory model

The thermoregulatory model explaining the origin of bipedalism is one of the simplest and most fanciful theories on the table, but it is a viable explanation. Dr. Peter Wheeler, a professor of evolutionary biology, proposes that bipedalism raises the amount of body surface area higher above the ground which results in a reduction in heat gain and helps heat dissipation. When a hominid is higher above the ground, the organism accesses more favorable wind speeds and temperatures. During heat seasons, greater wind flow results in a higher heat loss, which makes the organism more comfortable. Also, Wheeler explains that a vertical posture minimizes the direct exposure to the sun whereas quadrupedalism exposes more of the body to direct exposure.

Carrying models

Charles Darwin wrote that "Man could not have attained his present dominant position in the world without the use of his hands, which are so admirably adapted to the act of obedience of his will" Darwin (1871:52) and many models on bipedal origins are based on this line of thought. Gordon Hewes (1961) suggested that the carrying of meat "over considerable distances" (Hewes 1961:689) was the key factor. Isaac (1978) and Sinclair et al (1986) offered modifications of this idea as indeed did Lovejoy (1981) with his 'provisioning model' described above. Others, such as Nancy Tanner (1981) have suggested that infant carrying was key, whilst others have suggested stone tools and weapons drove the change. The problem with this is that humans were bipedal long before they had tools and weapons to carry. Furthermore, it doesn't appear that early proto-humans would have had to carry anything very far, as most of their needs were to be had nearby. It is a common error to attribute to proto-humans the same capacities as modern humans.

Wading hypothesis

The Aquatic ape hypothesis proposes that humans evolved bipedalism as a result of bipedal wading. Mammals that switch from quadrupedalism on land to bipedal wading appear mainly to be found among large primates, especially apes, with relatively few exceptions such as the grizzly bear. Bipedal wading has been observed in the bonobo, chimpanzee, lowland gorilla, orangutan, baboon and proboscis monkey. Bipedal wading provides the advantage of keeping the head above water for breathing. This article needs additional references or sources for verification. ... This article needs additional references or sources for verification. ... For the Brooklyn-based indie rock band, see Grizzly Bear (band). ... For other uses, see Bonobo (disambiguation). ... Type species Simia troglodytes Blumenbach, 1775 distribution of Species Pan troglodytes Pan paniscus Chimpanzee, often shortened to chimp, is the common name for the two extant species of apes in the genus Pan. ... Type species Troglodytes gorilla Savage, 1847 distribution of Gorilla Species Gorilla gorilla Gorilla beringei The gorilla, the largest of the living primates, is a ground-dwelling omnivore that inhabits the forests of Africa. ... This article is about the primate. ... For other uses, see Baboon (disambiguation). ... Binomial name Wurmb, 1787 The Proboscis Monkey, Nasalis larvatus also known as Long-nosed Monkey is a reddish-brown arboreal Old World monkey. ...

Turn-over pulse hypothesis

The theory is part of a general theory of human evolution known as the savanna hypothesis. This theory asserts that a major climate change occurred which induced an onset of drier conditions. These dry conditions severely reduced the amount of wooded habitats in the Pliocene era, about 2.5 million years ago. During this period where the forests became thin, the Australopithecus organisms had to evolve and change their habitats from the forest to grasslands. In order to remain effective in gathering food, the hominids had to travel long distances with food or tools, thus making quadrupedalism extremely inefficient. These hominids evolved into bipeds which made their treks along the grasslands much more efficient. All other theories of bipedalism, aside from the "wading hypothesis" are derivatives of this one. Some of the problems related to this theory have to do with dates. Bipedalism is evident in Australopithecus afarensis a million years before the thinning of the forests in question. It would be a million-and-a-half years or more before these proto-humans would have weapons sufficient to defend themselves or bring down large game. Midden piles from the time suggest a diet rich in turtles. Also, the savannas into which the humans were supposed to have gone, had limited edible vegetation, and an omnivore, like a human, would most likely head for a more diverse food supply, such as the eco-edge between the land and water. The few large apes which have adapted to savanna living have all become dietary specialists surviving on a single plant, the very opposite of an omnivore. None of those apes has developed bipedalism, apparently because it is less suited for swift movement ^{[citation needed]}. On the other hand, if humans developed their bipedalism at the water's edge, they wouldn't have been severely affected by receding forests. The savanna theory is the term used by those in favour of the aquatic ape hypothesis for an older version of the conventional (non-aquatic) understanding of how humans acquired bipedalism and other uniquely human characteristics. ... The Pliocene epoch (spelled Pleiocene in some older texts) is the period in the geologic timescale that extends from 5. ... Binomial name Johanson & White, 1978 Australopithecus afarensis is an extinct hominid which lived between 3. ...

Physiology of bipedalism

Bipedal movement occurs in a number of ways, and requires many mechanical and neurological adaptations. Some of these are described below.

Biomechanics

Engineers who study bipedal walking or running describe it as a repeatedly interrupted fall. The phenomenon of "tripping" is informative with regards to the "controlled falling" concept of walking and running. The common way to think of tripping is as pulling a leg out from under a walker or runner. In fact, however, merely stopping the movement of one leg of a walker, and merely slowing one leg of a runner, is sufficient to amount to tripping them. They were already "falling", and preventing the tripped leg from aborting that fall is sufficient to cause bipeds to collapse to the ground.

Energy-efficient means of standing bipedally involve constant adjustment of balance, and of course these must avoid overcorrection. For the superhero, see Feedback (Dark Horse Comics). ...

Efficient walking is more complicated than standing. It entails tipping slightly off-balance forward and to the side, and correcting balance with the right timing. In humans, walking is composed of several separate processes:

Running is an inherently continuous process, in contrast to walking; a bipedal creature or device, when efficiently running, is in a constant state of falling forward. This is maintained as relatively smooth motion only by repeatedly "catching oneself" with the right timing, but in the case of running only delaying the otherwise inevitable fall for the duration of another step.

Musculature

Bipedalism requires strong leg muscles, particularly in the thighs. Contrast in domesticated poultry the well muscled legs, against the small and bony wings. Likewise in humans, the quadriceps and hamstring muscles of the thigh are both so crucial to bipedal activities that each alone is much larger than even the well-developed biceps of the arms. Dogs and sheep were among the first animals to be domesticated. ... Ducks amongst other poultry The Poultry-dealer, after Cesare Vecellio Poultry is the category of domesticated birds kept for meat, eggs, and feathers. ... Muscles of the iliac and anterior femoral regions. ... In human anatomy, a hamstring refers to one of the tendons that makes up the borders of the space behind the knee. ...

Nervous system

The famous knee jerk (or patellar reflex) emphasizes the necessary bipedal control system: the only function served by the nerves involved being connected as they are is to ensure quick response to imminent disturbance of erect posture; it not only occurs without conscious mental activity, but also involves none of the nerves which lead from the leg to the brain. The patellar reflex or knee jerk is a monosynaptic reflex. ...

A less well-known aspect of bipedal neuroanatomy can be demonstrated in human infants who have not yet developed toward the ability to stand up. They can nevertheless run with great dexterity, provided they are supported in a vertical position and offered the stimulus of a moving treadmill beneath their feet. Neuroanatomy is the anatomy of the nervous system. ...

Respiration

A biped also has the ability to breathe whilst it runs. Humans usually take a breath every other stride when their aerobic system is functioning. During a sprint, at which point the anaerobic system kicks in, breathing slows until the anaerobic system can no longer sustain a sprint. This article or section should be merged with aerobic metabolism. ... Anaerobic respiration refers to the oxidation of molecules in the absence of oxygen to produce energy, in opposition to Aerobic respiration which does use oxygen. ...

Bipedal robots

For nearly the whole of the 20th century, bipedal robots were very difficult to construct and robot locomotion involved only wheels, treads, or multiple legs. Recent cheap and compact computing power has made two-legged robots more feasible. Some notable biped robots are ASIMO, HUBO and QRIO. Hondas ASIMO, an example of a humanoid robot A humanoid robot is a robot with its overall appearance based on that of the human body. ... ASIMO File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... ASIMO File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Press release photo of the most recent ASIMO model ASIMO ) is a humanoid robot created by Honda Motor Company. ... For other uses, see robot (disambiguation). ... Robot locomotion is the study of how to design robot appendages and control mechanisms to allow robots to move fluidly and efficiently. ... Press release photo of the most recent ASIMO model ASIMO ) is a humanoid robot created by Honda Motor Company. ... HUBO (íœ´ë³´ KHR-3) is a bi-pedal humanoid robot developed by the Korea Advanced Institute of Science and Technology (KAIST) and released on January 6, 2005 following a year of work. ... QRIO (Quest for cuRIOsity, originally named Sony Dream Robot or SDR) was to be bipedal humanoid entertainment robot marketed and sold by Sony to follow up on the success of its AIBO toy. ...

Bipedal molecule

In 2005, chemists at the University of California, Riverside developed the first bipedal molecule, 9,10-Dithioanthracene, which propels itself in a straight line when heated on a flat copper surface. Researchers believe the molecule has potential for use in molecular computers. The University of California, Riverside, commonly known as UCR or UC Riverside, is a public, coeducational university and one of ten campuses of the University of California. ... Chemical structure of 9,10- dithioanthracene 9,10-Dithioanthracene (DTA) is the first molecule ever to be able to walk in a straight line by, in effect, mimicking the bipedal motion of a human being. ... Molecular computers are massively parallel computers taking advantage of the compuational power of molecules. ...

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