Elastic mechanisms in primate locomotion

Rm, Alexander

doi:10.1127/zma/78/1991/315

Cited by 64 publications

(4 citation statements)

References 10 publications

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“…In addition, muscles acting to adduct the hip joint are comparably massive (~30% of muscle mass at the hip joint) in sloths, orangutans, and howler monkeys, as well as in the pelvic limb of other suspensory taxa (Liu et al, 2016), which suggests the ability of this functional group to facilitate grasping/clinging otherwise expected by universally strong digital flexors. It is further likely that the well‐developed limb adductors with four heads of the m. adductor in sloths also contributes to medial SRF and should act to maintain the horizontal position of CoM by more precise joint position control at the hip joint, all while preventing energy‐wasting by not oscillating the substrate (Alexander, 1991). This hypothesis needs to be verified with future analyses of SRF and muscle architectural properties in Bradypus .…”

Section: Discussionmentioning

confidence: 99%

Myology of the pelvic limb of the brown‐throated three‐toed sloth (Bradypus variegatus)

et al. 2022

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Tree sloths rely on their limb flexors for bodyweight support and joint stability during suspensory locomotion and posture. This study aims to describe the myology of three‐toed sloths and identify limb muscle traits that indicate modification for suspensorial habit. The pelvic limbs of the brown‐throated three‐toed sloth (Bradypus variegatus) were dissected, muscle belly mass was recorded, and the structural arrangements of the muscles were documented and compared with the available myological accounts for sloths. Overall, the limb musculature is simplified by containing muscles with generally long and parallel fascicles. A number of specific and informative muscle traits are additionally observed in the pelvic limb of B. variegatus: well‐developed hip flexors and hip extensors each displaying several fused bellies; massive knee flexors; two heads of the m. adductor longus and m. gracilis; robust digital flexors and flexor tendons; m. tibialis cranialis muscle complex originating from the tibia and fibula and containing a modified m. extensor digitorum I longus; appreciable muscle mass devoted to ankle flexion and hindfoot supination; only m. extensor digitorum brevis acts to extend the digits. Collectively, the findings for tree sloths emphasize muscle mass and organization for suspensory support namely by the hip flexors, knee flexors, and limb adductors, for which the latter two groups may stabilize suspensory postures by exerting appreciable medially‐directed force on the substrate. Specializations in the distal limb are also apparent for sustained purchase of the substrate by forceful digital flexion coupled with strong ankle flexion and supination of the hind feet, which is permitted by the reorganization of several digital extensors. Moreover, the reduction or loss of other digital flexor and ab‐adductor muscles marks a dramatic simplification of the intrinsic foot musculature in B. variegatus, the extent to which varies across extant species of two‐ and three‐toed tree sloths and likely is related to substrate preference/use.

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Section: Discussionmentioning

confidence: 99%

Myology of the pelvic limb of the brown‐throated three‐toed sloth (Bradypus variegatus)

et al. 2022

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“…Arboreal habitats are challenging because the discontinuity, variability, compliance (i.e., branch flexibility and deflection), and instability of the substrates inherently perturb the basic requirements of legged locomotion, that is, propulsion, balance, and path stability. For instance, the ability to generate mechanical work for propulsion may be reduced, as a substantial part of it is lost in deforming the substrate (Alexander, 1991a; Channon et al, 2011; Coward & Halsey, 2014; Demes et al, 1995; Lejeune et al, 1998), making high‐speed movement and acceleration difficult. As a result, the speed of progression and acceleration can hold functional significance in serving as proxies for the effectiveness in negotiating discontinuous and compliant substrates.…”

Section: Introductionmentioning

confidence: 99%

Vertical climbing in free‐ranging bonobos: An exploratory study integrating locomotor performance and substrate compliance

Druelle,

Leti,

Bokika Ngawolo

et al. 2024

American Journal of Biological Anthropology

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ObjectivesEcological factors and body size shape animal movement and adaptation. Large primates such as bonobos excel in navigating the demanding substrates of arboreal habitats. However, current approaches lack comprehensive assessment of climbing performance in free‐ranging individuals, limiting our understanding of locomotor adaptations. This study aims to explore climbing performance in free‐ranging bonobos and how substrate properties affect their behavior.MethodsWe collected data on the climbing performance of habituated bonobos, Pan paniscus, in the Bolobo Territory, Democratic Republic of Congo. We analyzed 46 climbing bouts (12 ascents, 34 descents) while moving on vertical substrates of varying diameter and compliance levels. This study assessed the average speed, peak acceleration, resting postures, and transitions between climbing and other locomotor modes.ResultsDuring climbing sequences and transitions, bonobos mitigate speed variations. They also exhibit regular pauses during climbing and show higher speeds during descent in contrast to their ascent. Regarding the influence of substrate properties, bonobos exhibit higher speed when ascending on thin and slightly flexible substrates, while they appear to achieve higher speeds when descending on large and stiff substrates, by using a “fire‐pole slide” submode.DiscussionBonobos demonstrate remarkable abilities for negotiating vertical substrates and substrate properties influence their performance. Our results support the idea that bonobos adopt a behavioral strategy that aligns with the notion of minimizing costs. Overall, the adoption of high velocities and the use of low‐cost resting postures may reduce muscle fatigue. These aspects could represent important targets of selection to ensure ecological efficiency in bonobos.

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“…Arboreal substrates are often discontinuous, and gaps must be crossed between trees while traveling (Graham & Socha, 2020). Such gaps typically lie between narrow and compliant terminal branches and may be of particular concern for arboreal leapers, given the need for high push‐off forces (Alexander, 1991; Bonser, 1999; Crompton et al, 1993). Most studies that have investigated the impact of substrate compliance on arboreal leaping have found that compliant supports absorb mechanical energy during push‐off, negatively impacting leaping performance (Crandell et al, 2018; Demes et al, 1995; Gilman et al, 2012; Gilman & Irschick, 2013; Hunt et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Pump and sway: Wild primates use compliant supports as a tool to augment leaping in the canopy

Janisch,

Myers,

Schapker

et al. 2024

American Journal of Biological Anthropology

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ObjectivesDespite qualitative observations of wild primates pumping branches before leaping across gaps in the canopy, most studies have suggested that support compliance increases the energetic cost of arboreal leaping, thus limiting leaping performance. In this study, we quantified branch pumping behavior and tree swaying in wild primates to test the hypothesis that these behaviors improve leaping performance.Materials and MethodsWe recorded wild colobine monkeys crossing gaps in the canopy and quantitatively tracked the kinematics of both the monkey and the compliant support during behavioral sequences. We also empirically measured the compliance of a sample of locomotor supports in the monkeys' natural habitat, allowing us to quantify the resonant properties of substrates used during leaping.ResultsAnalyses of three recordings show that adult red colobus monkeys (Piliocolobus tephrosceles) use branch compliance to their advantage by actively pumping branches before leaping, augmenting their vertical velocity at take‐off. Quantitative modeling of branch resonance periods, based on empirical measurements of support compliance, suggests that monkeys specifically employed branch pumping on relatively thin branches with protracted periods of oscillation. Finally, an additional four recordings show that both red colobus and black and white colobus monkeys (Colobus guereza) utilize tree swaying to cross large gaps, augmenting horizontal velocity at take‐off.DiscussionThis deliberate branch manipulation to produce a mechanical effect for stronger propulsion is consistent with the framework of instrumental problem‐solving. To our knowledge, this is the first study of wild primates which quantitatively shows how compliant branches can be used advantageously to augment locomotor performance.

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Elastic mechanisms in primate locomotion

Cited by 64 publications

References 10 publications

Myology of the pelvic limb of the brown‐throated three‐toed sloth (Bradypus variegatus)

Myology of the pelvic limb of the brown‐throated three‐toed sloth (Bradypus variegatus)

Vertical climbing in free‐ranging bonobos: An exploratory study integrating locomotor performance and substrate compliance

Pump and sway: Wild primates use compliant supports as a tool to augment leaping in the canopy

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