The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Shane K Maloney - One of the best experts on this subject based on the ideXlab platform.
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homeothermy and primate Bipedalism is water shortage or solar radiation the main threat to baboon papio hamadryas homeothermy
Journal of Human Evolution, 2009Co-Authors: Duncan Mitchell, Andrea Fuller, Shane K MaloneyAbstract:Abstract Other than the hominin lineage, baboons are the diurnally active primates that have colonized the arid plains of Africa most successfully. While the hominin lineage adopted Bipedalism before colonizing the open, dry plains, baboons retained a quadrupedal mode of locomotion. Because Bipedalism has been considered to reduce the thermoregulatory stress of inhabiting open dry plains, we investigated how baboons cope with thermal loads and water restriction. Using implanted data loggers, we measured abdominal temperature every 5 min in six unrestrained baboons while they were exposed to simulated desert conditions (15 °C at night rising to 35 °C during the day, with and without extra radiant heating), or an ambient temperature of 22 °C. At 22 °C, core temperature averaged 37.9 °C and cycled nychthemerally by 1.7 °C. Mean, minimum, and maximum daily core temperatures in euhydrated baboons in the simulated desert environments did not differ from the temperatures displayed in the 22 °C environment, even when radiant heating was applied. At 22 °C, restricting water intake did not affect core temperature. During the desert simulations, maximum core temperature increased significantly on each day of water deprivation, with the highest temperatures (>40 °C) on the third day in the simulation that included radiant heat. When drinking water heated to 38 °C was returned, core temperature decreased rapidly to a level lower than normal for that time of day. We conclude that baboons with access to water can maintain homeothermy in the face of high air temperatures and radiant heat loads, but that a lack of access to drinking water poses a major threat to baboon homeothermy. We speculate that any competitive thermoregulatory advantage of Bipedalism in early hominins was related to coping with water shortage in hot environments, and that their freed hands might have enabled them to transport enough water to avoid dangerous hyperthermia.
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homeothermy and primate Bipedalism is water shortage or solar radiation the main threat to baboon papio hamadryas homeothermy
Journal of Human Evolution, 2009Co-Authors: Duncan Mitchell, Andrea Fuller, Shane K MaloneyAbstract:Other than the hominin lineage, baboons are the diurnally active primates that have colonized the arid plains of Africa most successfully. While the hominin lineage adopted Bipedalism before colonizing the open, dry plains, baboons retained a quadrupedal mode of locomotion. Because Bipedalism has been considered to reduce the thermoregulatory stress of inhabiting open dry plains, we investigated how baboons cope with thermal loads and water restriction. Using implanted data loggers, we measured abdominal temperature every 5 min in six unrestrained baboons while they were exposed to simulated desert conditions (15 degrees C at night rising to 35 degrees C during the day, with and without extra radiant heating), or an ambient temperature of 22 degrees C. At 22 degrees C, core temperature averaged 37.9 degrees C and cycled nychthemerally by 1.7 degrees C. Mean, minimum, and maximum daily core temperatures in euhydrated baboons in the simulated desert environments did not differ from the temperatures displayed in the 22 degrees C environment, even when radiant heating was applied. At 22 degrees C, restricting water intake did not affect core temperature. During the desert simulations, maximum core temperature increased significantly on each day of water deprivation, with the highest temperatures (>40 degrees C) on the third day in the simulation that included radiant heat. When drinking water heated to 38 degrees C was returned, core temperature decreased rapidly to a level lower than normal for that time of day. We conclude that baboons with access to water can maintain homeothermy in the face of high air temperatures and radiant heat loads, but that a lack of access to drinking water poses a major threat to baboon homeothermy. We speculate that any competitive thermoregulatory advantage of Bipedalism in early hominins was related to coping with water shortage in hot environments, and that their freed hands might have enabled them to transport enough water to avoid dangerous hyperthermia.
Peter Aerts - One of the best experts on this subject based on the ideXlab platform.
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the mechanics of the gibbon foot and its potential for elastic energy storage during Bipedalism
The Journal of Experimental Biology, 2008Co-Authors: Evie Vereecke, Peter AertsAbstract:The mechanics of the modern human foot and its specialization for habitual Bipedalism are well understood. The windlass mechanism gives it the required stability for propulsion generation, and flattening of the arch and stretching of the plantar aponeurosis leads to energy saving. What is less well understood is how an essentially flat and mobile foot, as found in protohominins and extant apes, functions during Bipedalism. This study evaluates the hypothesis that an energy-saving mechanism, by stretch and recoil of plantar connective tissues, is present in the mobile gibbon foot and provides a two-dimensional analysis of the internal joint mechanics of the foot during spontaneous Bipedalism of gibbons using a four-link segment foot model. Available force and pressure data are combined with detailed foot kinematics, recorded with a high-speed camera at 250 Hz, to calculate the external joint moments at the metatarsophalangeal (MP), tarsometatarsal (TM) and talocrural (TC) joints. In addition, instantaneous joint powers are estimated to obtain insight into the propulsion-generating capacities of the internal foot joints. It is found that, next to a wide range of motion at the TC joint, substantial motion is observed at the TM and MP joint, underlining the importance of using a multi-segment foot model in primate gait analyses. More importantly, however, this study shows that although a compliant foot is less mechanically effective for push-off than a `rigid' arched foot, it can contribute to the generation of propulsion in bipedal locomotion via stretch and recoil of the plantarflexor tendons and plantar ligaments.
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speed modulation in hylobatid Bipedalism a kinematic analysis
Journal of Human Evolution, 2006Co-Authors: Evie Vereecke, Kristiaan Daout, Peter AertsAbstract:Gibbons are highly arboreal apes, and it is expected that their bipedal locomotion will show some particularities related to the arboreal environment. Previous research has shown that, during hylobatid Bipedalism, unsupported phases are rare and stride frequencies are relatively low. This study confirms previous findings, and we suggest that low stride frequencies and the absence of unsupported phases are ways to reduce disadvantageous branch oscillations during arboreal travel. Despite these restrictions, gibbons are able to locomote at a wide range of speeds, implying that they likely exploit other mechanisms to modulate their locomotor speed. To investigate this possibility, we collected video images of a large number of spontaneous bipedal bouts of four untrained white-handed gibbons by using an instrumented walkway with four synchronized cameras. These video images were digitized to obtain a quantification of the 3D kinematics of hylobatid Bipedalism. We defined a large number of spatiotemporal and kinematic gait variables, and the relationship between these gait variables and (dimensionless) speed was statistically tested. It was found that gibbons mainly increase stride length to increase their locomotor speed; the main speed-modulating mechanisms are hip and ankle excursion and coupled knee and ankle extension at toe-off. Although aerial phases are rare, gibbons generally adopt a bipedal bouncing gait at most speeds and a clear-cut gait transition, as seen in human locomotion, is absent. Comparison with human and bonobo Bipedalism showed that the variability of the 3D joint angles of the hind limb are comparable during human and gibbon Bipedalism, and much lower than during bonobo Bipedalism. The low variability found in gibbons might be related to constraints imposed by the arboreal environment. These arboreal constraints clearly affect the bipedal gait characteristics of gibbons, but do not constrain the ability to adopt a bipedal bouncing gait during terrestrial locomotion.
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the dynamics of hylobatid Bipedalism evidence for an energy saving mechanism
The Journal of Experimental Biology, 2006Co-Authors: Evie Vereecke, Kristiaan Daout, Peter AertsAbstract:When gibbons travel through the forest canopy, brachiation is alternated with short bipedal bouts over horizontal boughs. We know, from previous research, that brachiation is a very efficient locomotor mode that makes use of a pendulum-like exchange of energy, but to date, nothing is known about the dynamics of hylobatid Bipedalism. We wondered if gibbons also make use of an efficient gait mechanism during bipedal locomotion. To investigate this, we calculated oscillations of the centre of mass (COM), energy fluctuations, recovery rates and power outputs from the 3D ground reaction forces. These ground reaction forces were collected during spontaneous bipedal locomotion of four untrained white-handed gibbons ( Hylobates lar ) over an instrumented walkway (with an AMTI force plate). Excursions of the COM are relatively large during hylobatid Bipedalism and the fluctuations of potential and kinetic energy are largely in-phase. Together with the low inverted pendulum recovery rates, this points to a spring-mass mechanism during bipedal locomotion. Although the well-developed Achilles tendon of gibbons seems to be a good candidate for the storage and recoil of elastic energy, this is not supported by kinematical data of the ankle joint. Instead, we suggest that the knee extensor muscle tendon unit functions as an energy-saving mechanism during hylobatid Bipedalism, but detailed anatomical data is needed to confirm this suggestion. At low speeds gibbons use either pendular or spring mechanics, but a clear gait transition as seen in most quadrupedal mammals is absent. At moderate to high velocities, gibbons use a bouncing gait, generally without aerial phases. This supports the view that aerial phases are not a prerequisite for spring-mass mechanics and reinforces the claim that duty factor alone should not be used to distinguish between a walk and run.
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locomotion in bonobos pan paniscus differences and similarities between bipedal and quadrupedal terrestrial walking and a comparison with other locomotor modes
Journal of Anatomy, 2004Co-Authors: Kristiaan Daout, Evie Vereecke, Kirsten Schoonaert, Dirk De Clercq, L Van Elsacker, Peter AertsAbstract:One of the great ongoing debates in palaeo-anthropology is when, and how, hominids acquired habitual bipedal locomotion. The newly adopted bipedal gait and the ancestral quadrupedal gait are most often considered as very distinct, with each habitual locomotor mode showing corresponding anatomical adaptations. Bonobos (Pan paniscus), along with common chimpanzees (P. troglodytes), are the closest living relatives to humans and their locomotion is valuable for comparison with other primates, and to gain an insight in the acquisition of human Bipedalism. Bonobos are habitual quadrupeds, but they also engage in bipedal locomotion, both on terrestrial and in arboreal substrates. In terms of kinematics and dynamics, the contrast between bipedal and quadrupedal walking seems to be more subtle than one might expect. Apart from the trunk being approximately 37° more erect during bipedal locomotion, the leg movements are rather similar. Apart from the heel, plantar pressure distributions show subtle differences between bipedal and quadrupedal locomotion. Regardless, variability is high, and various intermediate forms of locomotion (e.g. tripedal walking) exist both in captivity and in the wild. Moreover, there is overlap between the characteristics of walking and other locomotor modes, as we show with new data of walking on an inclined pole and of vertical squat jumps. We suggest that there is great overlap between the many locomotor modes in bonobos, and that the required polyvalence is reflected in their anatomy. This may hamper the development of one highly specialized gait (i.e. Bipedalism), which would constrain performance of the other types of locomotion.
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Bipedalism in lizards whole body modelling reveals a possible spandrel
Philosophical Transactions of the Royal Society B, 2003Co-Authors: Peter Aerts, Kristiaan Daout, Raoul Van Damme, Bieke Van HooydonckAbstract:This paper illustrates how simple mechanical models based on morphological, ethological, ecological and phylogenetic data can add to discussions in evolutionary biology. Bipedal locomotion has evolved on numerous occasions in lizards. Traits that appear repeatedly in independent evolutionary lines are often considered adaptive, but the exact advantages of bipedal locomotion in lizards remain debated. Earlier claims that Bipedalism would increase maximal running speed or would be energetically advantageous have been questioned. Here, we use 'whole body' mechanical modelling to provide an alternative solution to the riddle. The starting point is the intermittent running style combined with the need for a high manoeuvrability characterizing many small lizard species. Manoeuvrability benefits from a caudal shift of the centre of mass of the body (body-COM), because forces to change the heading and to align the body to this new heading do not conflict with each other. The caudally situated body-COM, however, might result in a lift of the front part of the body when accelerating (intermittent style), thus resulting in bipedal running bouts. Based on a momentum-impulse approach the effect of acceleration is quantified for a mechanical model, a virtual lizard (three segments) based on the morphometrics of Acanthodactylus erythrurus (a small lacertid lizard). Biologically relevant input (dimensions, inertial properties, step cycle information, etc.) results in an important lift of the front part of the body and observable distances passively covered bipedally as a consequence of the acceleration. In this way, no functional explanation of the phenomenon of lizard Bipedalism is required and Bipedalism can probably be considered non-adaptive in many cases. This does not exclude, however, some species that may have turned this consequence to their benefit. For instance, instantaneous manipulation of the position of the centre of the body-COM allows stable, persisting bipedal running. Once this was achieved, the bipedal spandrel could be exploited further.
Duncan Mitchell - One of the best experts on this subject based on the ideXlab platform.
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homeothermy and primate Bipedalism is water shortage or solar radiation the main threat to baboon papio hamadryas homeothermy
Journal of Human Evolution, 2009Co-Authors: Duncan Mitchell, Andrea Fuller, Shane K MaloneyAbstract:Abstract Other than the hominin lineage, baboons are the diurnally active primates that have colonized the arid plains of Africa most successfully. While the hominin lineage adopted Bipedalism before colonizing the open, dry plains, baboons retained a quadrupedal mode of locomotion. Because Bipedalism has been considered to reduce the thermoregulatory stress of inhabiting open dry plains, we investigated how baboons cope with thermal loads and water restriction. Using implanted data loggers, we measured abdominal temperature every 5 min in six unrestrained baboons while they were exposed to simulated desert conditions (15 °C at night rising to 35 °C during the day, with and without extra radiant heating), or an ambient temperature of 22 °C. At 22 °C, core temperature averaged 37.9 °C and cycled nychthemerally by 1.7 °C. Mean, minimum, and maximum daily core temperatures in euhydrated baboons in the simulated desert environments did not differ from the temperatures displayed in the 22 °C environment, even when radiant heating was applied. At 22 °C, restricting water intake did not affect core temperature. During the desert simulations, maximum core temperature increased significantly on each day of water deprivation, with the highest temperatures (>40 °C) on the third day in the simulation that included radiant heat. When drinking water heated to 38 °C was returned, core temperature decreased rapidly to a level lower than normal for that time of day. We conclude that baboons with access to water can maintain homeothermy in the face of high air temperatures and radiant heat loads, but that a lack of access to drinking water poses a major threat to baboon homeothermy. We speculate that any competitive thermoregulatory advantage of Bipedalism in early hominins was related to coping with water shortage in hot environments, and that their freed hands might have enabled them to transport enough water to avoid dangerous hyperthermia.
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homeothermy and primate Bipedalism is water shortage or solar radiation the main threat to baboon papio hamadryas homeothermy
Journal of Human Evolution, 2009Co-Authors: Duncan Mitchell, Andrea Fuller, Shane K MaloneyAbstract:Other than the hominin lineage, baboons are the diurnally active primates that have colonized the arid plains of Africa most successfully. While the hominin lineage adopted Bipedalism before colonizing the open, dry plains, baboons retained a quadrupedal mode of locomotion. Because Bipedalism has been considered to reduce the thermoregulatory stress of inhabiting open dry plains, we investigated how baboons cope with thermal loads and water restriction. Using implanted data loggers, we measured abdominal temperature every 5 min in six unrestrained baboons while they were exposed to simulated desert conditions (15 degrees C at night rising to 35 degrees C during the day, with and without extra radiant heating), or an ambient temperature of 22 degrees C. At 22 degrees C, core temperature averaged 37.9 degrees C and cycled nychthemerally by 1.7 degrees C. Mean, minimum, and maximum daily core temperatures in euhydrated baboons in the simulated desert environments did not differ from the temperatures displayed in the 22 degrees C environment, even when radiant heating was applied. At 22 degrees C, restricting water intake did not affect core temperature. During the desert simulations, maximum core temperature increased significantly on each day of water deprivation, with the highest temperatures (>40 degrees C) on the third day in the simulation that included radiant heat. When drinking water heated to 38 degrees C was returned, core temperature decreased rapidly to a level lower than normal for that time of day. We conclude that baboons with access to water can maintain homeothermy in the face of high air temperatures and radiant heat loads, but that a lack of access to drinking water poses a major threat to baboon homeothermy. We speculate that any competitive thermoregulatory advantage of Bipedalism in early hominins was related to coping with water shortage in hot environments, and that their freed hands might have enabled them to transport enough water to avoid dangerous hyperthermia.
Brian G. Richmond - One of the best experts on this subject based on the ideXlab platform.
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laetoli footprints reveal bipedal gait biomechanics different from those of modern humans and chimpanzees
Proceedings of The Royal Society B: Biological Sciences, 2016Co-Authors: Kevin G Hatala, Brigitte Demes, Brian G. RichmondAbstract:Bipedalism is a key adaptation that shaped human evolution, yet the timing and nature of its evolution remain unclear. Here we use new experimentally based approaches to investigate the locomotor mechanics preserved by the famous Pliocene hominin footprints from Laetoli, Tanzania. We conducted footprint formation experiments with habitually barefoot humans and with chimpanzees to quantitatively compare their footprints to those preserved at Laetoli. Our results show that the Laetoli footprints are morphologically distinct from those of both chimpanzees and habitually barefoot modern humans. By analysing biomechanical data that were collected during the human experiments we, for the first time, directly link differences between the Laetoli and modern human footprints to specific biomechanical variables. We find that the Laetoli hominin probably used a more flexed limb posture at foot strike than modern humans when walking bipedally. The Laetoli footprints provide a clear snapshot of an early hominin bipedal gait that probably involved a limb posture that was slightly but significantly different from our own, and these data support the hypothesis that important evolutionary changes to hominin Bipedalism occurred within the past 3.66 Myr.
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orrorin tugenensis femoral morphology and the evolution of hominin Bipedalism
Science, 2008Co-Authors: Brian G. Richmond, William L. JungersAbstract:Bipedalism is a key human adaptation and a defining feature of the hominin clade. Fossil femora discovered in Kenya and attributed to Orrorin tugenensis, at 6 million years ago, purportedly provide the earliest postcranial evidence of hominin Bipedalism, but their functional and phylogenetic affinities are controversial. We show that the O. tugenensis femur differs from those of apes and Homo and most strongly resembles those of Australopithecus and Paranthropus, indicating that O. tugenensis was bipedal but is not more closely related to Homo than to Australopithecus. Femoral morphology indicates that O. tugenensis shared distinctive hip biomechanics with australopiths, suggesting that this complex evolved early in human evolution and persisted for almost 4 million years until modifications of the hip appeared in the late Pliocene in early Homo.
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comment on origin of human Bipedalism as an adaptation for locomotion on flexible branches
Science, 2007Co-Authors: David R Begun, Brian G. Richmond, David S StraitAbstract:Thorpe et al. (Reports, 1 June 2007, p. 1328) concluded that human Bipedalism evolved from a type of bipedal posture they observed in extant orangutans with seemingly human-like extended knees. However, humans share knuckle-walking characters with African apes that are absent in orangutans. These are most parsimoniously explained by positing a knuckle-walking precursor to human Bipedalism.
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origin of human Bipedalism the knuckle walking hypothesis revisited
American Journal of Physical Anthropology, 2001Co-Authors: Brian G. Richmond, David R Begun, David S StraitAbstract:Some of the most long-standing questions in paleoanthropology concern how and why human Bipedalism evolved. Over the last century, many hypotheses have been offered on the mode of locomotion from which Bipedalism originated. Candidate ancestral adaptations include monkey-like arboreal or terrestrial quadrupedalism, gibbon- or orangutan-like (or other forms of) climbing and suspension, and knuckle-walking. This paper reviews the history of these hypotheses, outlines their predictions, and assesses them in light of current phylogenetic, comparative anatomical, and fossil evidence. The functional significance of characteristics of the shoulder and arm, elbow, wrist, and hand shared by African apes and humans, including their fossil relatives, most strongly supports the knuckle-walking hypothesis, which reconstructs the ancestor as being adapted to knuckle-walking and arboreal climbing. Future fossil discoveries, and a clear understanding of anthropoid locomotor anatomy, are required to ultimately test these hypotheses. If knuckle-walking was an important component of the behavioral repertoire of the prebipedal human ancestor, then we can reject scenarios on the origin of Bipedalism that rely on a strictly arboreal ancestor. Moreover, paleoenvironmental data associated with the earliest hominins, and their close relatives, contradict hypotheses that place the agents of selection for bipedality in open savanna habitats. Existing hypotheses must explain why Bipedalism would evolve from an ancestor that was already partly terrestrial. Many food acquisition and carrying hypotheses remain tenable in light of current evidence.
Evie Vereecke - One of the best experts on this subject based on the ideXlab platform.
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the mechanics of the gibbon foot and its potential for elastic energy storage during Bipedalism
The Journal of Experimental Biology, 2008Co-Authors: Evie Vereecke, Peter AertsAbstract:The mechanics of the modern human foot and its specialization for habitual Bipedalism are well understood. The windlass mechanism gives it the required stability for propulsion generation, and flattening of the arch and stretching of the plantar aponeurosis leads to energy saving. What is less well understood is how an essentially flat and mobile foot, as found in protohominins and extant apes, functions during Bipedalism. This study evaluates the hypothesis that an energy-saving mechanism, by stretch and recoil of plantar connective tissues, is present in the mobile gibbon foot and provides a two-dimensional analysis of the internal joint mechanics of the foot during spontaneous Bipedalism of gibbons using a four-link segment foot model. Available force and pressure data are combined with detailed foot kinematics, recorded with a high-speed camera at 250 Hz, to calculate the external joint moments at the metatarsophalangeal (MP), tarsometatarsal (TM) and talocrural (TC) joints. In addition, instantaneous joint powers are estimated to obtain insight into the propulsion-generating capacities of the internal foot joints. It is found that, next to a wide range of motion at the TC joint, substantial motion is observed at the TM and MP joint, underlining the importance of using a multi-segment foot model in primate gait analyses. More importantly, however, this study shows that although a compliant foot is less mechanically effective for push-off than a `rigid' arched foot, it can contribute to the generation of propulsion in bipedal locomotion via stretch and recoil of the plantarflexor tendons and plantar ligaments.
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speed modulation in hylobatid Bipedalism a kinematic analysis
Journal of Human Evolution, 2006Co-Authors: Evie Vereecke, Kristiaan Daout, Peter AertsAbstract:Gibbons are highly arboreal apes, and it is expected that their bipedal locomotion will show some particularities related to the arboreal environment. Previous research has shown that, during hylobatid Bipedalism, unsupported phases are rare and stride frequencies are relatively low. This study confirms previous findings, and we suggest that low stride frequencies and the absence of unsupported phases are ways to reduce disadvantageous branch oscillations during arboreal travel. Despite these restrictions, gibbons are able to locomote at a wide range of speeds, implying that they likely exploit other mechanisms to modulate their locomotor speed. To investigate this possibility, we collected video images of a large number of spontaneous bipedal bouts of four untrained white-handed gibbons by using an instrumented walkway with four synchronized cameras. These video images were digitized to obtain a quantification of the 3D kinematics of hylobatid Bipedalism. We defined a large number of spatiotemporal and kinematic gait variables, and the relationship between these gait variables and (dimensionless) speed was statistically tested. It was found that gibbons mainly increase stride length to increase their locomotor speed; the main speed-modulating mechanisms are hip and ankle excursion and coupled knee and ankle extension at toe-off. Although aerial phases are rare, gibbons generally adopt a bipedal bouncing gait at most speeds and a clear-cut gait transition, as seen in human locomotion, is absent. Comparison with human and bonobo Bipedalism showed that the variability of the 3D joint angles of the hind limb are comparable during human and gibbon Bipedalism, and much lower than during bonobo Bipedalism. The low variability found in gibbons might be related to constraints imposed by the arboreal environment. These arboreal constraints clearly affect the bipedal gait characteristics of gibbons, but do not constrain the ability to adopt a bipedal bouncing gait during terrestrial locomotion.
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the dynamics of hylobatid Bipedalism evidence for an energy saving mechanism
The Journal of Experimental Biology, 2006Co-Authors: Evie Vereecke, Kristiaan Daout, Peter AertsAbstract:When gibbons travel through the forest canopy, brachiation is alternated with short bipedal bouts over horizontal boughs. We know, from previous research, that brachiation is a very efficient locomotor mode that makes use of a pendulum-like exchange of energy, but to date, nothing is known about the dynamics of hylobatid Bipedalism. We wondered if gibbons also make use of an efficient gait mechanism during bipedal locomotion. To investigate this, we calculated oscillations of the centre of mass (COM), energy fluctuations, recovery rates and power outputs from the 3D ground reaction forces. These ground reaction forces were collected during spontaneous bipedal locomotion of four untrained white-handed gibbons ( Hylobates lar ) over an instrumented walkway (with an AMTI force plate). Excursions of the COM are relatively large during hylobatid Bipedalism and the fluctuations of potential and kinetic energy are largely in-phase. Together with the low inverted pendulum recovery rates, this points to a spring-mass mechanism during bipedal locomotion. Although the well-developed Achilles tendon of gibbons seems to be a good candidate for the storage and recoil of elastic energy, this is not supported by kinematical data of the ankle joint. Instead, we suggest that the knee extensor muscle tendon unit functions as an energy-saving mechanism during hylobatid Bipedalism, but detailed anatomical data is needed to confirm this suggestion. At low speeds gibbons use either pendular or spring mechanics, but a clear gait transition as seen in most quadrupedal mammals is absent. At moderate to high velocities, gibbons use a bouncing gait, generally without aerial phases. This supports the view that aerial phases are not a prerequisite for spring-mass mechanics and reinforces the claim that duty factor alone should not be used to distinguish between a walk and run.
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locomotion in bonobos pan paniscus differences and similarities between bipedal and quadrupedal terrestrial walking and a comparison with other locomotor modes
Journal of Anatomy, 2004Co-Authors: Kristiaan Daout, Evie Vereecke, Kirsten Schoonaert, Dirk De Clercq, L Van Elsacker, Peter AertsAbstract:One of the great ongoing debates in palaeo-anthropology is when, and how, hominids acquired habitual bipedal locomotion. The newly adopted bipedal gait and the ancestral quadrupedal gait are most often considered as very distinct, with each habitual locomotor mode showing corresponding anatomical adaptations. Bonobos (Pan paniscus), along with common chimpanzees (P. troglodytes), are the closest living relatives to humans and their locomotion is valuable for comparison with other primates, and to gain an insight in the acquisition of human Bipedalism. Bonobos are habitual quadrupeds, but they also engage in bipedal locomotion, both on terrestrial and in arboreal substrates. In terms of kinematics and dynamics, the contrast between bipedal and quadrupedal walking seems to be more subtle than one might expect. Apart from the trunk being approximately 37° more erect during bipedal locomotion, the leg movements are rather similar. Apart from the heel, plantar pressure distributions show subtle differences between bipedal and quadrupedal locomotion. Regardless, variability is high, and various intermediate forms of locomotion (e.g. tripedal walking) exist both in captivity and in the wild. Moreover, there is overlap between the characteristics of walking and other locomotor modes, as we show with new data of walking on an inclined pole and of vertical squat jumps. We suggest that there is great overlap between the many locomotor modes in bonobos, and that the required polyvalence is reflected in their anatomy. This may hamper the development of one highly specialized gait (i.e. Bipedalism), which would constrain performance of the other types of locomotion.