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Bipedie ( Latin to "double", pes / pedis "foot") is locomotion , for example walking or hopping, on two legs ("two-leggedness"). Terrestrial vertebrates or machines that usually move bipedally are called bipedes ("bipeds").

A distinction is made between habitual (obligatory, habitual) bipedia and facultative (occasional) bipedia. Habitual bipedalism affects living beings that are fully adapted to bipedal locomotion, such as humans. Facultative bipedia affects animals that can straighten up and possibly walk for short distances, but are not morphologically fully adapted to this form of locomotion . This is the case with gibbons (Hylobatidae) and chimpanzees ( Pan ).

An ostrich , one of the fastest living bipeds

Types of bipedia

Touching the ground when walking, jumping and running.

There are a number of states of motion that are commonly associated with bipedalism.

  1. Stand. Standing motionless on both (generally straight) legs. For most bipeds, this is an active process that requires constant readjustment of their balance.
  2. Go . One foot (or hand - on hands when walking) is placed in front of the other, with at least one foot touching the ground at all times.
  3. To run. One foot is placed in front of the other, with no foot touching the ground at certain times.
  4. Jump. Movement through a series of jumps in which both feet are moved at the same time.
  5. Hopping run . Longer periods of non-ground contact than running combined with periods in which one or both feet touch the ground.

Features of bipedia

Bipedia and its associated traits can provide several benefits to one species:

  • Improved perception. Some evolutionary biologists have suggested that a critical stage in the evolution of some or even all bipeds has been the ability to stand, which generally improves the ability to see (and perhaps otherwise detect) distant hazards or resources.
  • Free front legs. In vertebrate species for which the development of additional limbs would mean an enormous genetic change, Bipedie can be used to free the front limbs for such functions as handicrafts (in primates), flies (in birds), digging (giant pangolin) or fighting (bears) ).
  • Wade. Raccoons and some primates can assume a two-legged stance in the water, allowing them to stand or walk in deeper water while still being able to breathe air.
  • In animals without a flexible spine, such as lizards or cockroaches, transient bipedes can increase the speed of their walking. Some bipeds are fast and persistent runners, so the ostrich or the red kangaroo can reach around 60–70 km / h.
  • Greater range. The giraffe gazelle assumes a two-legged position to graze the leaves of trees.
  • Camouflage. It has been suggested that bipedes in octopuses allow them to move around while keeping the rest of the body motionless for camouflage.

Evolution of man

Orangutan , standing upright in the branches.
The female gorilla Leah uses a branch as a support when crossing a body of water.

There are many hypotheses as to how and why the bipedia developed in the early ancestors of the genus Homo , and there are also various hypotheses as to when. The finds of fossils give reason to believe that the bipedalism developed before the enlargement of the human brain and that they are in the form of circle of early apes - detectable especially the loss of the gripping foot - repeatedly developed independently. The various hypotheses are not necessarily mutually exclusive, and a number of influencing factors could have worked together to lead to the hominini bipedic . The facultative bipedial ability in some primates suggests that human bipedalism is an evolution of them.

This is particularly supported by the hypothesis of the development of upright walking on trees. Researchers observed orangutans on the island of Sumatra for a year, according to a 2007 report in Science magazine . The analysis of around 3000 movements showed that the orangutans move on very thin twigs on two legs, holding onto branches hanging over them with their hands and balancing their weight with their arms. According to the theory derived from this, when the African forests gradually disappeared during a dry period, the ancestors of the hominini reacted by “moving” to the ground, where they further developed and perfected the upright gait. The find by Danuvius guggenmosi published in 2019 was also interpreted as confirmation of this hypothesis. One of the complementary hypotheses on the development of upright gait is that bonobos and gorillas , for example, live near rivers or in the mangrove , where they move in the water with their bodies submerged while, for example, they hold on to branches above them.

Human children go through an early stage of development in which they hold on to each other with their hands to practice walking upright. According to the basic biogenetic rule, the human ancestors should have passed through a corresponding phylogenetic stage of development.

The oldest fossil evidence of a foot comparable in function to humans is a fully preserved, 3.2 million year old metatarsal bone of Australopithecus afarensis (archive number AL 333-160), the characteristics of which recognize the presence of both a longitudinal arch and a transverse arch both of which act as "shock absorbers" when walking upright. The oldest surviving footprints of upright hominini come from Laetoli and are approximately 3.6 million years old.

Two-legged animals

Two-legged locomotion has evolved repeatedly and independently, mostly in vertebrates . For example, with birds such as the cassowary and their fossil relatives, the dinosaurs, all of which, with the exception of the sauropodomorpha, were bipedal runners. It is believed that all theropod dinosaurs descended from a two-legged ancestor, perhaps similar to the eoraptor . Rat birds such as the ostrich living today can reach speeds of up to 65 km / h. Many theropoda, especially the maniraptora , are also believed to have been able to travel at similar speeds. Two- legged locomotion also developed in a number of other dinosaur lineages, such as the Iguanodon . Bipedia also appears to have evolved in the crocodiles , a sister group of dinosaurs and birds. Effigia okeeffeae - a member of the crocodiles from the Triassic - is taken for a biped. Penguins are interesting birds for bipedalism in that they keep their bodies upright while other birds keep them more horizontal.

Biped locomotion is less common among mammals , most of which are quadrupeds (tetrapods). The most species-rich group of mammals that use two-legged locomotion are the kangaroos and their relatives. However, these tend to move around primarily by hopping, which is very different from humans, birds and theropods. There are also different groups of hopping rodents , such as the kangaroo rats . A primate - the Sifaka - also moves around hopping on the ground. Possibly the only other mammals besides humans that also move bipedally in an alternating gait rather than hopping are various other primates such as gibbons when they are on the ground and capuchin monkeys . The latter continuously transport objects on their hind legs, both horizontally across the ground and vertically in the branches, as has been demonstrated in the case of the capuchins with back stripes .

Limited examples of two-leggedness are found in some other mammals. For example, bonobos and proboscis monkeys , both of which live in forests that are often flooded, wade through water in a two-legged position. Under certain circumstances, bonobos, proboscis monkeys and, more rarely, some other primates also walk or stand on two legs. A number of other animals, such as rats , crouch on their hind legs to hold on to food as they eat. The raccoon often stands upright or crouched in the water to use its hands to manipulate food, stones, and sticks. Beavers also occasionally move on two legs when carrying branches. Some animals, such as bears , can straighten up during physical fights and move on two legs so that they can better use their paws as weapons. A number of mammals, such as ground squirrels and meerkats , also stand on their hind legs to explore their surroundings, but without walking on them. After all, the giraffe gazelle is known to stand on its hind legs to eat leaves from trees. Pangolins , anteaters and armadillos can also stand up on their hind legs, sometimes when looking for food, sometimes when defending themselves . For some extinct sloths such as the giant Megatherium or other large ground sloths , this is also assumed. In addition to individual trace fossils , the body's center of gravity, which has been shifted far back, indicates this. However, a sometimes assumed obligatory two-legged locomotion can be ruled out for anatomical reasons. Another extinct group, the odd- toed chalicotheria , may also have behaved similarly. An unusual form of restricted bipedia is shown by the spotted skunks , who, when they feel threatened, stand on their forelegs, which allows them to direct their anal glands , which can expel a pungent secretion, at the attacker while they are still holding the attacker look at.

Bipedia is completely unknown in amphibians . Bipedia is rare among the non- Archosaur reptiles , but it can be found when certain lizards run "upright" . An interesting example can be found in at least one species of basilisk lizard , which can walk a certain distance over the surface of water using this method. Bipedia in the form of standing upright can also be found in some insects such as cockroaches . Otherwise bipedal locomotion is not known in arthropods . Bipeds are almost exclusively land vertebrates . However, there are at least two types of octopus that are known to move bipedally. This type of locomotion seems to allow them to remain somewhat camouflaged while moving quickly by using the shape e.g. Take a coconut or seaweed and move on the tips of two of their arms.

Exceptional cases

Many animals that do not naturally use bipedal locomotion can be trained to walk on their hind legs. Animals that are missing limbs due to injuries or congenital malformations can adapt to two-legged locomotion, either on two hind legs or on one front and one hind leg.

Some animals can also be trained to walk on their forelegs, although this method lacks practical advantages other than for the purpose of gymnastic variety in entertainment. People can also learn to walk with the help of their arms or only with their arms ( handstand ). This is unusual and requires mental and physical exercise, as do many types of physical exercise, as otherwise injuries from lack of protection from stunted or unbalanced muscles that are too poorly developed for these movements can result.

Some unusual solitary primate individuals have been known to be bipedal. There was one documented case of a macaque walking entirely on two legs after recovering from a serious illness, and at least one example of a captured chimpanzee who only walked upright.

Physiology of Bipedia

Biped locomotion occurs in several ways and requires many mechanical and neurological adjustments. Some of them are described below.


Engineers who investigate two-legged walking or running describe it as repetitively interrupted falling. The phenomenon of stumbling is instructive in terms of the "controlled fall" concept of walking or running. The common way to think of stumbling is as pulling a leg away from a walker or runner. In fact, however, merely stopping the movement of one leg of the walker, or merely slowing down one leg of the runner, is sufficient to trip them. They already “fall” beforehand, and it is enough to prevent the stumbling leg from stopping this fall in order to cause bipeds to fall to the ground.

  • Stand

An energy-efficient two-legged standing requires constant regulation of balance, in which of course overcorrection must be avoided.

  • Go

Walking efficiently is more complicated than standing. It requires the slight tilting out of balance forwards and to the side and the timely correction of the balance. In humans, walking is made up of various individual processes:

  • sway back and forth between the feet
  • Push your toes forward to maintain speed
  • combined interruptions in swaying and tilting the ankles in the other direction
  • Bend and straighten the knee to stop the "falling forward"

When walking calmly, longer legs take longer steps that are slower. This is due to the fact that the legs act as a pendulum during this movement.

  • To run

Running is an inherently ongoing process, as opposed to walking. A bipedal being or device, when running efficiently, is in a constant state of falling forward. This is only maintained through repeated self-catching at the right time, but in the case of running only with the postponement of the almost inevitable case for the duration of a further step as a relatively steady movement.

  • Jump


Bipedia requires strong leg muscles, especially in the thighs. It is only in domesticated poultry that you contrast the muscular legs with the small bony wings. Likewise, the quadriceps and hamstrings are so important for bipedal processes in humans that each of these muscles is significantly larger than even a well-developed arm biceps .

The faster the walk is performed, the more strenuous it is. The steady gait is less tiring than standing, as the legs are alternately relieved. This is not the case when the vehicle is standing, so it can be more than twice as strenuous as the quiet walk.

Nervous system

The patellar tendon reflex (also: knee tendon reflex ) is a well-known example of the extremely fast control system in bipeds, with the help of which an impending disturbance of the upright posture is counteracted: As is usual for reflexes, the individual reacts completely unconsciously, and the reaction does not take place on any nerve tracts that lead from the leg to the brain.

A less well-known aspect of biped neuroanatomy may show up in human toddlers who have not yet developed the ability to stand. They can still run with great dexterity, provided that they are supported in a vertical position and that the stimulus of a moving treadmill is offered under their feet.


A biped also has the ability to breathe while running. People usually breathe every other step when their aerobic system is working. During a sprint, breathing slows down as soon as the anaerobic system starts, until the anaerobic system can no longer support the sprint.

Two-legged robots

ASIMO - a two-legged robot

Mobile robots are usually built to move around with wheels, chains or rails - depending on their specific task. In contrast to specialized musculoskeletal systems, bipede robots pose greater challenges in terms of both mechanical construction and control. Unmatched achievements in this area were achieved in the early 1980s by Marc Raibert at MIT .

The best known and most advanced bipedal robots are ASIMO (from Honda ), Qrio (from Sony ), Johnnie (from TUM ) and the HRP series

See also


Web links

Wiktionary: Bipedie  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. C. Owen Lovejoy : Evolution of Human Walking. In: Scientific American. Volume 259, No. 5, 1988, pp. 118–125, full text (PDF)
  2. WEH Harcourt-Smith, Leslie C. Aiello : Fossils, feet and the evolution of human bipedal locomotion. In: Journal of Anatomy . Volume 204, No. 5, 2004, pp. 403-416, doi: 10.1111 / j.0021-8782.2004.00296.x
  3. SKS Thorpe et al .: Origin of Human Bipedalism as an Adaptation for Locomotion on Flexible Branches. Science, Volume 316, 2007, pp. 1328-1331, doi: 10.1126 / science.1140799 ; see: : "Upright on the branch".
  4. Madelaine Böhme et al .: A new Miocene ape and locomotion in the ancestor of great apes and humans. In: Nature. Volume 575, 2019, pp. 489-493, doi: 10.1038 / s41586-019-1731-0 .
  6. ^ Carol V. Ward, William H. Kimbel, and Donald C. Johanson : Complete Fourth Metatarsal and Arches in the Foot of Australopithecus afarensis. In: Science , Volume 331, No. 6018, 2011, pp. 750-753, doi: 10.1126 / science.1201463
  7. National Geographics News: Dino-Era Fossil Reveals Two-Footed Croc Relative
  8. Tiago Falotico, Agumi Inaba, William C. McGrew and Eduardo Ottoni example: Vertical bipedal locomotion in wild bearded capuchin monkeys (Sapajus libidinosus). Primates 57 (4), 2016, pp. 533-540; doi: 10.1007 / s10329-016-0542-2
  9. Adrià Casinos: Bipedalism and quadrupedalism in Megatherium: an attempt at biomechanical reconstruction. Lethaia 29, 1996, pp. 87-96
  10. ^ R. Ernesto Blanco and Ada Czerwonogora: The gait of Megatherium Cuvier 1796 (Mammalia, Xenarthra, Megatheriidae). Senckenbergiana biologica 83 (1), 2003, pp. 61-68
  11. M. Susana Bargo, Sergio F. Vizcaíno, Fernando M. Archuby and R. Ernesto Blanco: Limb bone proportions, strength and digging in some Lujanian (Late Pleistocene-Early Holocene) mylodontid ground sloths (Mammalia, Xenarthra). Journal of Vertebrate Paleontology 20 (3), 2000, pp. 601-610
  12. Franz Daffner: The growth of people. Anthropological study. 2nd Edition. Engelmann, Leipzig 1902, p. 356.
  13. MIT: 3D Biped (1989-1995)
  14. ^ Technical University of Munich: JOHNNIE walking machine
  15. Heise: HRP-4C: The next supermodel?
  16. AIST