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Tracy L Kivell - One of the best experts on this subject based on the ideXlab platform.
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manual skills for food processing by mountain gorillas gorilla beringei beringei in bwindi impenetrable national park uganda
Biological Journal of The Linnean Society, 2019Co-Authors: Johanna Neufuss, Jana Baeumer, Tatyana Humle, Tracy L Kivell, Martha M RobbinsAbstract:Although gorillas rarely use tools in the wild, their manipulative skills during plant processing may be similar to those of other tool-using great apes. Virunga mountain gorillas are known for the complexity in their methods of thistle and nettle plant preparation in the wild. However, there has been no comparable data on food processing in the population of mountain gorillas from the Bwindi Impenetrable National Park, Uganda. We investigated the manual actions and hand grips used when accessing edible parts of two hard-to-process plants defended by stinging hairs, epidermis or periderm (i.e., peel of Urera hypselodendron and pith of Mimulopsis arborescens) and one undefended plant (i.e., leaves of Momordica foetida) in 11 Bwindi wild mountain gorillas (Gorilla beringei beringei) using video records ad libitum. Similar to thistle feeding by Virunga gorillas, Bwindi gorillas used the greatest number of manual actions for the most hard-to-process plant (U. hypselodendron), the actions were ordered in several key stages and organised hierarchically. The demands of processing plant material elicited 19 different grips and variable thumb postures, of which three grips were new and 16 grips have either been previously reported or show clear similarities to grips used by other wild and captive African apes and humans. Moreover, our study only partly supports a functional link between diet and hand morphology in mountain gorillas and suggests that the gorilla hand is best adapted to forceful grasping that is required for both manipulation and Arboreal Locomotion.
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hand pressures during Arboreal Locomotion in captive bonobos pan paniscus
The Journal of Experimental Biology, 2018Co-Authors: Diana Samuel, Sandra Nauwelaerts, Jeroen M G Stevens, Tracy L KivellAbstract:Evolution of the human hand has undergone a transition from use during Locomotion to use primarily for manipulation. Previous comparative morphological and biomechanical studies have focused on potential changes in manipulative abilities during human hand evolution, but few have focused on functional signals for Arboreal Locomotion. Here, we provide this comparative context though the first analysis of hand loading in captive bonobos during Arboreal Locomotion. We quantify pressure experienced by the fingers, palm and thumb in bonobos during vertical Locomotion, suspension and Arboreal knuckle-walking. Results show that pressure experienced by the fingers is significantly higher during knuckle-walking compared with similar pressures experienced by the fingers and palm during suspensory and vertical Locomotion. Peak pressure is most often experienced at or around the third digit in all locomotor modes. Pressure quantified for the thumb is either very low or absent, despite the thumb making contact with the substrate during all suspensory and vertical locomotor trials. Unlike chimpanzees, the bonobos do not show a rolling pattern of digit contact with the substrate during Arboreal knuckle-walking but, instead, digits 3 and 4 typically touch down first and digit 5 almost always made contact with the substrate. These results have implications for interpreting extant and fossilised hand morphology; we expect bonobo (and chimpanzee) bony morphology to primarily reflect the biomechanical loading of knuckle-walking, while functional signals for Arboreal Locomotion in fossil hominins are most likely to appear in the fingers, particularly digit 3, and least likely to appear in the morphology of the thumb.
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comparison of hand use and forelimb posture during vertical climbing in mountain gorillas gorilla beringei beringei and chimpanzees pan troglodytes
American Journal of Physical Anthropology, 2017Co-Authors: Johanna Neufuss, Jana Baeumer, Tatyana Humle, Tracy L Kivell, Martha M RobbinsAbstract:Objectives: Studies on grasping and limb posture during Arboreal Locomotion in great apes in their natural environment are scarce and thus, attempts to correlate behavioral and habitat differences with variation in morphology are limited. The aim of this study is to compare hand use and forelimb posture during vertical climbing in wild, habituated mountain gorillas (Gorilla beringei beringei) and semi-free-ranging chimpanzees (Pan troglodytes) to assess differences in the climbing styles that may relate to variation in hand or forelimb morphology and body size. Materials and methods: We investigated hand use and forelimb posture during both ascent and descent vertical climbing in 15 wild mountain gorillas and eight semi-free-ranging chimpanzees, using video records obtained ad libitum. Results: In both apes, forelimb posture was correlated with substrate size during both ascent and descent climbing. While climbing, both apes used power grips and diagonal power grips, including three different thumb postures. Mountain gorillas showed greater ulnar deviation of the wrist during vertical descent than chimpanzees, and the thumb played an important supportive role when gorillas vertically descended lianas. Discussion: We found that both apes generally had the same grip preferences and used similar forelimb postures on supports of a similar size, which is consistent with their overall similarity in hard and soft tissue morphology of the hand and forelimb. However, some species-specific differences in morphology appear to elicit slightly different grasping strategies during vertical climbing between mountain gorillas and chimpanzees.
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gait characteristics and spatio temporal variables of climbing in bonobos pan paniscus
American Journal of Primatology, 2016Co-Authors: Kirsten Schoonaert, Tracy L Kivell, Diana Samuel, Sandra Nauwelaerts, Kristiaan Daout, Willem Talloen, Peter AertsAbstract:Although much is known about the terrestrial Locomotion of great apes, their Arboreal Locomotion has been studied less extensively. This study investigates Arboreal Locomotion in bonobos (Pan paniscus), focusing on the gait characteristics and spatio-temporal variables associated with Locomotion on a pole. These features are compared across different substrate inclinations (0°, 30°, 45°, 60°, and 90°), and horizontal quadrupedal walking is compared between an Arboreal and a terrestrial substrate. Our results show greater variation in footfall patterns with increasing incline, resulting in more lateral gait sequences. During climbing on Arboreal inclines, smaller steps and strides but higher stride frequencies and duty factors are found compared to horizontal Arboreal walking. This may facilitate better balance control and dynamic stability on the Arboreal substrate. We found no gradual change in spatio-temporal variables with increasing incline; instead, the results for all inclines were clustered together. Bonobos take larger strides at lower stride frequencies and lower duty factors on a horizontal Arboreal substrate than on a flat terrestrial substrate. We suggest that these changes are the result of the better grip of the grasping feet on an Arboreal substrate. Speed modulation of the spatio-temporal variables is similar across substrate inclinations and between substrate types, suggesting a comparable underlying motor control. Finally, we contrast these variables of Arboreal inclined climbing with those of terrestrial bipedal Locomotion, and briefly discuss the results with respect to the origin of habitual bipedalism. Am. J. Primatol. 78:1165-1177, 2016. © 2016 Wiley Periodicals, Inc.
Johanna Neufuss - One of the best experts on this subject based on the ideXlab platform.
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manual skills for food processing by mountain gorillas gorilla beringei beringei in bwindi impenetrable national park uganda
Biological Journal of The Linnean Society, 2019Co-Authors: Johanna Neufuss, Jana Baeumer, Tatyana Humle, Tracy L Kivell, Martha M RobbinsAbstract:Although gorillas rarely use tools in the wild, their manipulative skills during plant processing may be similar to those of other tool-using great apes. Virunga mountain gorillas are known for the complexity in their methods of thistle and nettle plant preparation in the wild. However, there has been no comparable data on food processing in the population of mountain gorillas from the Bwindi Impenetrable National Park, Uganda. We investigated the manual actions and hand grips used when accessing edible parts of two hard-to-process plants defended by stinging hairs, epidermis or periderm (i.e., peel of Urera hypselodendron and pith of Mimulopsis arborescens) and one undefended plant (i.e., leaves of Momordica foetida) in 11 Bwindi wild mountain gorillas (Gorilla beringei beringei) using video records ad libitum. Similar to thistle feeding by Virunga gorillas, Bwindi gorillas used the greatest number of manual actions for the most hard-to-process plant (U. hypselodendron), the actions were ordered in several key stages and organised hierarchically. The demands of processing plant material elicited 19 different grips and variable thumb postures, of which three grips were new and 16 grips have either been previously reported or show clear similarities to grips used by other wild and captive African apes and humans. Moreover, our study only partly supports a functional link between diet and hand morphology in mountain gorillas and suggests that the gorilla hand is best adapted to forceful grasping that is required for both manipulation and Arboreal Locomotion.
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comparison of hand use and forelimb posture during vertical climbing in mountain gorillas gorilla beringei beringei and chimpanzees pan troglodytes
American Journal of Physical Anthropology, 2017Co-Authors: Johanna Neufuss, Jana Baeumer, Tatyana Humle, Tracy L Kivell, Martha M RobbinsAbstract:Objectives: Studies on grasping and limb posture during Arboreal Locomotion in great apes in their natural environment are scarce and thus, attempts to correlate behavioral and habitat differences with variation in morphology are limited. The aim of this study is to compare hand use and forelimb posture during vertical climbing in wild, habituated mountain gorillas (Gorilla beringei beringei) and semi-free-ranging chimpanzees (Pan troglodytes) to assess differences in the climbing styles that may relate to variation in hand or forelimb morphology and body size. Materials and methods: We investigated hand use and forelimb posture during both ascent and descent vertical climbing in 15 wild mountain gorillas and eight semi-free-ranging chimpanzees, using video records obtained ad libitum. Results: In both apes, forelimb posture was correlated with substrate size during both ascent and descent climbing. While climbing, both apes used power grips and diagonal power grips, including three different thumb postures. Mountain gorillas showed greater ulnar deviation of the wrist during vertical descent than chimpanzees, and the thumb played an important supportive role when gorillas vertically descended lianas. Discussion: We found that both apes generally had the same grip preferences and used similar forelimb postures on supports of a similar size, which is consistent with their overall similarity in hard and soft tissue morphology of the hand and forelimb. However, some species-specific differences in morphology appear to elicit slightly different grasping strategies during vertical climbing between mountain gorillas and chimpanzees.
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hand use and posture during manipulative behaviours and Arboreal Locomotion in african apes
2017Co-Authors: Johanna NeufussAbstract:The skill with which primates use their hands to explore and interact with the environment sets them apart from most other mammals. The non-human primate hand serves an important functional role during not only terrestrial and Arboreal Locomotion, but also enhanced grasping and manipulative behaviours. Understanding how living primates use their hands for these various functions is fundamental for understanding the order Primates and the evolution of humans within this order. While bipedalism and the extraordinary manipulative abilities of our human hand for manufacturing stone tools are considered to be unique, their origins remain controversial. Understanding this evolutionary shift in human hand use from Locomotion to manipulation requires comparative studies of hand use in our closest living relatives, the African apes (chimpanzees, bonobos and gorillas). To date, however, little research has been done on African ape daily hand use, including both locomotor and manipulative behaviours, especially in natural environments. This dissertation will address this gap by conducting detailed studies of hand use and posture during two complex manipulative behaviours (i.e., plant-processing, nut-cracking) and Arboreal Locomotion (i.e., vertical climbing) in the natural environment of African apes. I conducted the first comprehensive analysis of bonobo palm oil nut-cracking in a natural environment at the Lola ya Bonobo sanctuary, Democratic Republic of the Congo. All eighteen bonobos showed exclusive laterality for using the hammerstone and there was a significant group-level right-hand bias. The study revealed 15 hand grips for holding differently-sized and -weighted hammerstones, 10 of which had not been previously described in the literature. The findings also demonstrated that bonobos select the most effective hammerstones when nut-cracking and that bonobos, despite rarely using tools in the wild, can be efficient nut-crackers with a skill level that is similar to palm oil nut-cracking chimpanzees of Bossou, Guinea. I further provided the first insights into the manual skills of Bwindi mountain gorillas by examining hand-use strategies, hand grips, and hand-preference (i.e., laterality) during the processing of three different plants. Two of these plants are woody-stemmed plants for which the food is more challenging to access in comparison to leaves, lacking physical defenses that are relatively simple to process. Bwindi gorillas used the greatest number of hand actions to process the most complex plant food (i.e., peel-processing) similar to complex thistle feeding by Virunga mountain gorillas. The manipulative actions were ordered in several key stages organised hierarchically. The demands of manipulating natural foods elicited 19 different hand grips and variable thumb postures, of which three grips were new and 16 grips have either been previously reported or show clear similarities to grips used by other wild and captive African apes and humans. A higher degree of lateralisation was elicited for the most complex behaviour of peel-processing but the strength of laterality was only moderate, suggesting that peel-processing is not as complex as thistle leaf-processing by Virunga gorillas. Finally, I examined for the first time hand use, forelimb posture and gait chacteristics during vertical climbing in wild, habituated mountain gorillas (Gorilla beringei) of the Bwindi Impenetrable National Park, Uganda, and semi-free-ranging chimpanzees (Pan troglodytes) of the Chimfunshi Wildlife Orphanage Trust, Zambia, both within a natural environment. This research revealed that both apes used power grips and a diagonal power grip, involving three different thumb postures. Gorillas showed greater ulnar deviation of the wrist during climbing than chimpanzees, and the thumb played an important supportive role when vertically descending compliant substrates in gorillas. Comparisons of temporal gait parameters showed that large-bodied gorillas exhibited significant longer cycle duration, lower stride frequency and generally a higher duty factor than chimpanzees. This quantitative analysis revealed that mountain gorillas adapt their climbing strategy to accommodate their large body mass in a similar manner found in captive western lowland gorillas, and that chimpanzees showed less variation in their climbing strategy than has been documented in captive bonobos. In summary, this study demonstrates the importance of forceful hand grips and the variable use of the thumb relative to substrate size in both ape species, and particularly in large-bodied mountain gorillas as they face more biomechanical challenges during vertical climbing than smaller-bodied chimpanzees. Together, this dissertation provides new insights into the functional link between hand morphology and behaviour in African apes in their natural environments that may ultimately generate more informed reconstructions of fossil hominin locomotor and manipulative behaviours. Furthermore, this research shows that the suite of "unique human grips" or "unique human manipulative abilities" that have typically defined humans is getting much smaller the more we learn about African apes, particularly in their complex natural environment where the hand has to adjust to varying foods and Arboreal substrates, and where individuals have ample opportunity to learn and develop high manipulative skills.
Bruce C. Jayne - One of the best experts on this subject based on the ideXlab platform.
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the effects of slope and branch structure on the Locomotion of a specialized Arboreal colubrid snake boiga irregularis
Journal of Experimental Zoology, 2015Co-Authors: Bruce C. Jayne, Greg ByrnesAbstract:The surfaces in Arboreal habitats have variable diameters, slopes, and branching structure that pose functional challenges for animal Locomotion. Nevertheless, many lineages of snakes have independently evolved Arboreality. We tested the effects of Arboreal habitat structure on the Locomotion of a highly Arboreal species, the brown tree snake (Boiga irregularis), moving on seven diameters (0.6–21 cm) of cylinders oriented at three slopes (0°, 45°, 90°) and with or without pegs. Intermediate diameters of horizontal cylinders maximized speed, and some of the large-diameter cylinders without pegs were impassable when they were inclined. With increased slope the snakes were slower, and they changed from using lateral undulation with sliding contact and balancing to concertina Locomotion with periodic static gripping. The presence of pegs increased the speeds of the brown tree snakes and resulted in them only using lateral undulation. Surface diameter, slope, and the occurrence of pegs also had widespread significant effects on the kinematics of the brown tree snakes. Overall, compared to anatomically less specialized corn snakes, brown tree snakes use more lateral undulation, are usually much faster, and are able to move on a wider variety of surfaces. Unlike some of the trade-offs found previously between two less specialized species of snakes with different stoutness when they used modes of Arboreal Locomotion that involved either balancing or gripping, the slender-bodied brown tree snakes excel at both. Hence, this species may not only be a “jack of all trades” but also a master of many. J. Exp. Zool. 323A: 309–321, 2015. © 2015 Wiley Periodicals, Inc.
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the effects of slope and branch structure on the Locomotion of a specialized Arboreal colubrid snake boiga irregularis
Journal of Experimental Zoology, 2015Co-Authors: Bruce C. Jayne, Greg ByrnesAbstract:The surfaces in Arboreal habitats have variable diameters, slopes, and branching structure that pose functional challenges for animal Locomotion. Nevertheless, many lineages of snakes have independently evolved Arboreality. We tested the effects of Arboreal habitat structure on the Locomotion of a highly Arboreal species, the brown tree snake (Boiga irregularis), moving on seven diameters (0.6–21 cm) of cylinders oriented at three slopes (0°, 45°, 90°) and with or without pegs. Intermediate diameters of horizontal cylinders maximized speed, and some of the large-diameter cylinders without pegs were impassable when they were inclined. With increased slope the snakes were slower, and they changed from using lateral undulation with sliding contact and balancing to concertina Locomotion with periodic static gripping. The presence of pegs increased the speeds of the brown tree snakes and resulted in them only using lateral undulation. Surface diameter, slope, and the occurrence of pegs also had widespread significant effects on the kinematics of the brown tree snakes. Overall, compared to anatomically less specialized corn snakes, brown tree snakes use more lateral undulation, are usually much faster, and are able to move on a wider variety of surfaces. Unlike some of the trade-offs found previously between two less specialized species of snakes with different stoutness when they used modes of Arboreal Locomotion that involved either balancing or gripping, the slender-bodied brown tree snakes excel at both. Hence, this species may not only be a “jack of all trades” but also a master of many. J. Exp. Zool. 323A: 309–321, 2015. © 2015 Wiley Periodicals, Inc.
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Perch size and structure have species-dependent effects on the Arboreal Locomotion of rat snakes and boa constrictors
Journal of Experimental Biology, 2011Co-Authors: Bruce C. Jayne, Michael P. HerrmannAbstract:SUMMARY Arboreal habitats create diverse challenges for animal Locomotion, but the numerical and phylogenetic diversity of snakes that climb trees suggest that their overall body plan is well suited for this task. Snakes have considerable diversity of axial anatomy, but the functional consequences of this diversity for Arboreal Locomotion are poorly understood because of the lack of comparative data. We simulated diverse Arboreal surfaces to test whether environmental structure had different effects on the Locomotion of snakes belonging to two distantly related species with differences in axial musculature and stoutness. On most cylindrical surfaces lacking pegs, both species used concertina Locomotion, which always involved periodic stopping and gripping but was kinematically distinct in the two species. On horizontal cylinders that were a small fraction of body diameter, the boa constrictors used a balancing form of lateral undulation that was not observed for rat snakes. For all snakes the presence of pegs elicited lateral undulation and enhanced speed. For both species maximal speeds decreased with increased incline and were greatest on cylinders with intermediate diameters that approximated the diameter of the snakes. The frictional resistances that we studied had small effects compared with those of cylinder diameter, incline and the presence of pegs. The stouter and more muscular boa constrictors were usually faster than the rat snakes when using the gripping gait, whereas rat snakes were faster when using lateral undulation on the surfaces with pegs. Thus, variation in environmental structure had several highly significant effects on locomotor mode, performance and kinematics that were species dependent.
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effects of perch diameter and incline on the kinematics performance and modes of Arboreal Locomotion of corn snakes elaphe guttata
The Journal of Experimental Biology, 2007Co-Authors: Henry C Astley, Bruce C. JayneAbstract:Animals moving through Arboreal habitats face several functional challenges, including fitting onto and moving on cylindrical branches with variable diameters and inclines. In contrast to lizards and primates, the Arboreal Locomotion of snakes is poorly understood, despite numerous snake species being Arboreal. We quantified the kinematics and performance of corn snakes (Elaphe guttata) moving on seven cylinders (diameters 1.6-21 cm) with five inclines (horizontal, +/-45 degrees and +/-90 degrees) and through horizontal tunnels of corresponding widths. When perches were inclined at either 45 degrees or 90 degrees , snakes were unable to move uphill or downhill on the larger diameters. None of the Locomotion on perches conformed to any previously described mode of limbless Locomotion. On horizontal and uphill perches snakes performed a variant of concertina Locomotion with periodic stopping and gripping. When moving downhill, snakes often slid continuously while grasping the perch to reduce their speed. Mean forward velocity decreased both with increased incline and with increased perch diameter, contrary to the beneficial effect of increased diameter on the speeds of lizards. Both tunnel width and perch diameter had widespread and similar effects on kinematics. When perches and tunnels were narrower, the snakes had more lateral bends at shallower angles. The numerous effects of perch diameter on kinematics and the similarity to tunnel concertina Locomotion emphasize the importance of fit as a limitation in Arboreal Locomotion of snakes. However, the slower speeds on horizontal perches compared to tunnels also suggest that balance and grip may further limit locomotor performance.
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maneuvering in an Arboreal habitat the effects of turning angle on the Locomotion of three sympatric ecomorphs of anolis lizards
The Journal of Experimental Biology, 2001Co-Authors: Timothy E Higham, Matthew S Davenport, Bruce C. JayneAbstract:Although the maximal speeds of straight-ahead running are well-documented for many species of Anolis and other lizards, no previous study has experimentally determined the effects of turning on the locomotor performance of a lizard. Anolis lizards are a diverse group of Arboreal species, and the discrete paths created by networks of perches in Arboreal environments often force animals to turn in their natural habitats. For three species of Anolis with similar overall body size but different shape, we quantified the escape locomotor performance for Arboreal Locomotion on 4.8 cm diameter perches that were straight (0°) or had turning angles of 30° and 90°. The turning angle had widespread significant effects that were often species-dependent. This was shown by measuring the average gross velocity (including the times while the lizards paused) of the three species covering the middle 30 cm of a racetrack with either 30° or 90° turns. The results were expressed as a percentage of the gross velocity over the same distance on a straight racetrack. The values obtained for A . grahami (99 % for 30° turns and 79 % for 90° turns) showed a smaller effect of turning angle than for A . lineatopus (79 % for 30° turns and 50 % for 90° turns) and A . valencienni (74 % for 30° turns and 48 % for 90° turns). Consequently, the rank order of species based on speed depended on the angle of the turn. Some of the magnitudes of decreased locomotor speed associated with turning exceeded those reported previously for the effects of decreasing perch diameter for these species. For all species, more pausing occurred with increased turning angle, with the twig ecomorph ( A . valencienni ) pausing the most. Approximately half the individuals of each species jumped to traverse the 90° turn, but some of the potential benefits of jumping for increasing speed were offset by pauses associated with preparing to jump or recovering balance immediately after a jump. The tail of Anolis lizards may facilitate the substantial rotation (>60°) of the body that often occurred in the airborne phase of the jumps.
Andrew R Lammers - One of the best experts on this subject based on the ideXlab platform.
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turning the corner in quadrupedal Arboreal Locomotion kinetics of changing direction while running in the siberian chipmunk tamias sibiricus
Journal of Experimental Zoology, 2013Co-Authors: Andrew R Lammers, Kelley M SufkaAbstract:Arboreal animals frequently change directions during Locomotion on tree branches, trunks, or twigs. Linear and rotational impulses required to change direction and rotate the body while running are largely unexplored. We trained Siberian chipmunks (Tamias sibiricus) to run on narrow cylindrical trackways. The first trackway was straight and the second had a 45° bend to the right. A force pole collected substrate reaction forces and torques, and linear and rotational impulses were calculated. When the chipmunks ran and jumped across the bend, they exerted strong impulses to the left, pushing the body to the right. Before the bend the substrate reaction yaw angular impulse rotated the animal to the new heading. After passing over the 45° bend in the trackway, opposing yaw angular impulses were exerted to stop the body's rotation. Rolling angular impulses were mostly similar between straight and turning trials. We conclude that mediolateral forces are more important than craniocaudal forces to change direction in Locomotion. Yaw angular impulse is necessary to start and stop the rotation of the body around the center of mass. To avoid rolling during turns, the chipmunks relied on banking rather than exerting rolling torques.
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stability during Arboreal Locomotion
Theoretical Mechanics, 2011Co-Authors: Andrew R Lammers, Ulrich ZurcherAbstract:Arboreal Locomotion – traveling on the branches, twigs, and trunks of trees and woody shrubs – is very common among mammals. Most primates, many rodents, marsupials, carnivores, and even an occasional artiodactyl travel on Arboreal substrates to forage, escape predators, and acquire shelter. Arboreal supports are usually far enough from the ground that a slip or fall could cause serious injury or death, or deprive the animal of a mate, food, or energy. Thus, stability is of great importance for an animal traveling on Arboreal supports. The considerable variation among Arboreal supports makes stability during Locomotion a mechanical challenge. Supports vary in diameter, slope, compliance, texture, direction (that is, bends or curves in a branch), and number and distribution. Furthermore there may be interaction among these variables; for example, compliance varies with diameter – thinner branches are more compliant than thick branches. Also, the thin branches frequently have leaves that act like sails in the wind, causing even more movement in the substrate. Substrate texture often varies with diameter, where narrow twigs have smoother bark than large branches or trunks. Therefore one might expect a considerable number of morphological, behavioral, and biomechanical mechanisms to enhance stability on Arboreal supports. Stability can be divided into two categories: static and dynamic. Static stability is the process by which objects at rest remain stable, i.e., neither move (translation) nor rotate about a point or axis. For example, a table is statically stable because the forces and moments (torques) produced by gravity (weight) are balanced by ground reaction forces and the moments generated by them. One way an animal might remain stable is by not moving and adhering to or gripping the support; this definition is the ultimate example of static stability in an animal. Although this strategy allows no movement, it is nevertheless a valid locomotor strategy for an animal attempting to travel on an Arboreal support subjected to a sudden gust of wind or other disturbance (Stevens, 2003). This analysis also applies when the animal walks very slowly, but fails when it walks or runs at considerable speed. Because the distribution of the mass is changing from one instant to the next, the forces and torques necessary to maintain static stability would also change with time. That is, it requires an active control by the nervous system. Because stability is critical, it is very likely that the animal employs both active and passive control (Full et al., 2002). Passive control can be due to dynamic processes of the animal’s body, and is referred to as dynamic stability. For example, a hiker might cross a stream or river by running across a fallen log; the rotation of the limbs around the hips and shoulder
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torque around the center of mass dynamic stability during quadrupedal Arboreal Locomotion in the siberian chipmunk tamias sibiricus
Zoology, 2011Co-Authors: Andrew R Lammers, Ulrich ZurcherAbstract:When animals travel on tree branches, avoiding falls is of paramount importance. Animals swiftly running on a narrow branch must rely on movement to create stability rather than on static methods. We examined how Siberian chipmunks (Tamias sibiricus) remain stable while running on a narrow tree branch trackway. We examined the pitch, yaw, and rolling torques around the center of mass, and hypothesized that within a stride, any angular impulse (torque during step time) acting on the center of mass would be canceled out by an equal and opposite angular impulse. Three chipmunks were videotaped while running on a 2cm diameter branch trackway. We digitized the videos to estimate center of mass and center of pressure positions throughout the stride. A short region of the trackway was instrumented to measure components of the substrate reaction force. We found that positive and negative pitch angular impulse was by far the greatest in magnitude. The anterior body was pushed dorsally (upward) when the forelimbs landed simultaneously, and then the body pitched in the opposite direction as both hindlimbs simultaneously made contact. There was no considerable difference between yaw and rolling angular impulses, both of which were small and equal between fore- and hindlimbs. Net angular impulses around all three axes were usually greater than or less than zero (not balanced). We conclude that the chipmunks may balance out the torques acting on the center of mass over the course of two or more strides, rather than one stride as we hypothesized.
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the effects of substrate texture on the mechanics of quadrupedal Arboreal Locomotion in the gray short tailed opossum monodelphis domestica
Journal of Experimental Zoology, 2009Co-Authors: Andrew R LammersAbstract:Among small mammals, the ability to move on tree trunks, branches, and twigs is nearly ubiquitous. Performance and locomotor mechanics on Arboreal substrates may be influenced by variation in the coefficient of friction between the hands/feet of the animal and the surface of the Arboreal substrate. To test this, I examined speed, substrate reaction forces, and torque around the long axis of two cylindrical trackways with rough and smooth surfaces in gray short-tailed opossums (Monodelphis domestica). Speed was determined with videography, and forces and torques were measured by an instrumented section of the trackway. The opossums traveled more slowly on the smooth Arboreal trackway. There was also significant interaction between limb (forelimbs, hindlimbs) and substrate texture (rough, smooth) in braking, propulsive, and laterally directed impulses. Running on the smooth trackway had the effect of reducing some between-limb (forelimb vs. hindlimb) differences. Stability on the rough trackway was probably maintained by relatively high momentum, but on the smooth trackway, the opossums used static methods (many limbs contacting the substrate, greater muscular effort, lower momentum) to remain stable and avoid toppling. Clearly, momentum and dynamics are often important biomechanical considerations for this generalized mammal. Highly Arboreal animals can remain dynamically stable on a wider variety of substrate textures.
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mechanics of torque generation during quadrupedal Arboreal Locomotion
Journal of Biomechanics, 2008Co-Authors: Andrew R Lammers, Timothy GauntnerAbstract:Quadrupedal animals moving on Arboreal substrates face unique challenges to maintain stability. The torque generated by the limbs around the long axis of a branch during Locomotion may clarify how the animals remain stable on Arboreal supports. We sought to determine what strategy gray short-tailed opossums (Monodelphis domestica) use to exert torque and avoid toppling. The opossums moved across a branch trackway about half the diameter of their bodies. Part of the trackway was instrumented to measure substrate reaction forces and torque around the long axis of the branch. Kinematic analysis was used to estimate the center of pressure of the manus and pes; from center of pressure and vertical and mediolateral forces, the torque generated by substrate reaction forces versus muscular effort could be determined. Forelimbs generated significantly greater torque than hindlimbs, which is probably explained by the greater weight-bearing role of the forelimbs. Fore- and hindlimbs generated torque in opposite directions because contralateral fore- and hindlimbs typically contacted the branch. Torque generated by muscular effort, however, was often in the same direction in both fore- and hindlimbs. The muscle-generated torque is likely the result of mediolateral movement of the center of mass caused by mediolateral undulation of the torso. These results bear an important implication for the study of Arboreal Locomotion: center of mass dynamics are at least as important as static positions. M. domestica is a good representative for a primitive mammal, and comparisons with Arboreal specialists will shed light on how proficient Arboreal Locomotion evolved.
Jana Baeumer - One of the best experts on this subject based on the ideXlab platform.
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manual skills for food processing by mountain gorillas gorilla beringei beringei in bwindi impenetrable national park uganda
Biological Journal of The Linnean Society, 2019Co-Authors: Johanna Neufuss, Jana Baeumer, Tatyana Humle, Tracy L Kivell, Martha M RobbinsAbstract:Although gorillas rarely use tools in the wild, their manipulative skills during plant processing may be similar to those of other tool-using great apes. Virunga mountain gorillas are known for the complexity in their methods of thistle and nettle plant preparation in the wild. However, there has been no comparable data on food processing in the population of mountain gorillas from the Bwindi Impenetrable National Park, Uganda. We investigated the manual actions and hand grips used when accessing edible parts of two hard-to-process plants defended by stinging hairs, epidermis or periderm (i.e., peel of Urera hypselodendron and pith of Mimulopsis arborescens) and one undefended plant (i.e., leaves of Momordica foetida) in 11 Bwindi wild mountain gorillas (Gorilla beringei beringei) using video records ad libitum. Similar to thistle feeding by Virunga gorillas, Bwindi gorillas used the greatest number of manual actions for the most hard-to-process plant (U. hypselodendron), the actions were ordered in several key stages and organised hierarchically. The demands of processing plant material elicited 19 different grips and variable thumb postures, of which three grips were new and 16 grips have either been previously reported or show clear similarities to grips used by other wild and captive African apes and humans. Moreover, our study only partly supports a functional link between diet and hand morphology in mountain gorillas and suggests that the gorilla hand is best adapted to forceful grasping that is required for both manipulation and Arboreal Locomotion.
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comparison of hand use and forelimb posture during vertical climbing in mountain gorillas gorilla beringei beringei and chimpanzees pan troglodytes
American Journal of Physical Anthropology, 2017Co-Authors: Johanna Neufuss, Jana Baeumer, Tatyana Humle, Tracy L Kivell, Martha M RobbinsAbstract:Objectives: Studies on grasping and limb posture during Arboreal Locomotion in great apes in their natural environment are scarce and thus, attempts to correlate behavioral and habitat differences with variation in morphology are limited. The aim of this study is to compare hand use and forelimb posture during vertical climbing in wild, habituated mountain gorillas (Gorilla beringei beringei) and semi-free-ranging chimpanzees (Pan troglodytes) to assess differences in the climbing styles that may relate to variation in hand or forelimb morphology and body size. Materials and methods: We investigated hand use and forelimb posture during both ascent and descent vertical climbing in 15 wild mountain gorillas and eight semi-free-ranging chimpanzees, using video records obtained ad libitum. Results: In both apes, forelimb posture was correlated with substrate size during both ascent and descent climbing. While climbing, both apes used power grips and diagonal power grips, including three different thumb postures. Mountain gorillas showed greater ulnar deviation of the wrist during vertical descent than chimpanzees, and the thumb played an important supportive role when gorillas vertically descended lianas. Discussion: We found that both apes generally had the same grip preferences and used similar forelimb postures on supports of a similar size, which is consistent with their overall similarity in hard and soft tissue morphology of the hand and forelimb. However, some species-specific differences in morphology appear to elicit slightly different grasping strategies during vertical climbing between mountain gorillas and chimpanzees.