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16. The long limb bones of the StW 573 Australopithecus skeleton from Sterkfontein Member 2: Descriptions and proportions

Author

Heaton, Jason L., primary, Pickering, Travis Rayne, additional, Carlson, Kristian J., additional, Crompton, Robin H., additional, Jashashvili, Tea, additional, Beaudet, Amélie, additional, Bruxelles, Laurent, additional, Kuman, Kathleen, additional, Heile, Andrea J., additional, Stratford, Dominic, additional, and Clarke, Ronald J., additional

Published
2019
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19. Hindlimb muscle architecture in non-human great apes and a comparison of methods for analysing inter-species variation

Author

Myatt, Julia P, Crompton, Robin H, and Thorpe, Susannah K S

Subjects
Pongo abelii, Gorilla gorilla, Pan troglodytes, Species Specificity, Cadaver, Linear Models, Animals, Original Articles, Pan paniscus, Muscle, Skeletal, Hindlimb
Abstract

By relating an animal's morphology to its functional role and the behaviours performed, we can further develop our understanding of the selective factors and constraints acting on the adaptations of great apes. Comparison of muscle architecture between different ape species, however, is difficult because only small sample sizes are ever available. Further, such samples are often comprised of different age-sex classes, so studies have to rely on scaling techniques to remove body mass differences. However, the reliability of such scaling techniques has been questioned. As datasets increase in size, more reliable statistical analysis may eventually become possible. Here we employ geometric and allometric scaling techniques, and ancovas (a form of general linear model, GLM) to highlight and explore the different methods available for comparing functional morphology in the non-human great apes. Our results underline the importance of regressing data against a suitable body size variable to ascertain the relationship (geometric or allometric) and of choosing appropriate exponents by which to scale data. ancova models, while likely to be more robust than scaling for species comparisons when sample sizes are high, suffer from reduced power when sample sizes are low. Therefore, until sample sizes are radically increased it is preferable to include scaling analyses along with ancovas in data exploration. Overall, the results obtained from the different methods show little significant variation, whether in muscle belly mass, fascicle length or physiological cross-sectional area between the different species. This may reflect relatively close evolutionary relationships of the non-human great apes; a universal influence on morphology of generalised orthograde locomotor behaviours or, quite likely, both.

Published
2011

20. Vector field statistics for objective center-of-pressure trajectory analysis during gait, with evidence of scalar sensitivity to small coordinate system rotations

Author

Pataky, Todd C; HVcUjFkV, Robinson, Mark A, Vanrenterghem, Jos, Savage, Russell, Bates, Karl T, Crompton, Robin H, Pataky, Todd C; HVcUjFkV, Robinson, Mark A, Vanrenterghem, Jos, Savage, Russell, Bates, Karl T, and Crompton, Robin H

Abstract

Center of pressure (COP) trajectories summarize the complex mechanical interaction between the foot and a contacted surface. Each trajectory itself is also complex, comprising hundreds of instantaneous vectors over the duration of stance phase. To simplify statistical analysis often a small number of scalars are extracted from each COP trajectory. The purpose of this paper was to demonstrate how a more objective approach to COP analysis can avoid particular sensitivities of scalar extraction analysis. A previously published dataset describing the effects of walking speed on plantar pressure (PP) distributions was re-analyzed. After spatially and temporally normalizing the data, speed effects were assessed using a vector-field paired Hotelling's T-2 test. Results showed that, as walking speed increased, the COP moved increasingly posterior at heel contact, and increasingly laterally and anteriorly between similar to 60 and 85% stance, in agreement with previous independent studies. Nevertheless, two extracted scalars disagreed with these results. Furthermore, sensitivity analysis found that a relatively small coordinate system rotation of 5.5 degrees reversed the mediolateral null hypothesis rejection decision. Considering that the foot may adopt arbitrary postures in the horizontal plane, these sensitivity results suggest that non-negligible uncertainty may exist in mediolateral COP effects. As compared with COP scalar extraction, two key advantages of the vector-field approach are: (i) coordinate system independence, (ii) continuous statistical data reflecting the temporal extents of COP trajectory changes.

Published
2014

25. Human-like external function of the foot, and fully upright gait, confirmed in the 3.66 million year old Laetoli hominin footprints by topographic statistics, experimental footprint-formation and computer simulation

Author

Crompton, Robin H., primary, Pataky, Todd C., additional, Savage, Russell, additional, D'Août, Kristiaan, additional, Bennett, Matthew R., additional, Day, Michael H., additional, Bates, Karl, additional, Morse, Sarita, additional, and Sellers, William I., additional

Published
2011
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30. Factors Affecting the Compliance and Sway Properties of Tree Branches Used by the Sumatran Orangutan (Pongo abelii).

Author

van Casteren, Adam, Sellers, William I., Thorpe, Susannah K. S., Coward, Sam, Crompton, Robin H., and Ennos, A. Roland

Subjects
TREE branches, PONGO abelii, PLANT habitats, PLANT ecology, COMPUTATIONAL biology
Abstract

The tropical arboreal environment is a mechanically complex and varied habitat. Arboreal inhabitants must adapt to changes in the compliance and stability of supports when moving around trees. Because the orangutan is the largest habitual arboreal inhabitant, it is unusually susceptible to branch compliance and stability and therefore represents a unique animal model to help investigate how animals cope with the mechanical heterogeneity of the tropical canopy. The aim of this study was to investigate how changes in compliance and time of oscillation of branches are related to easily observable traits of arboreal supports. This should help predict how supports react mechanically to the weight and mass of a moving orangutan, and suggest how orangutans themselves predict branch properties. We measured the compliance and time of oscillation of branches from 11 tree species frequented by orangutans in the rainforest of Sumatra. Branches were pulled at several points along their length using a force balance at the end of a stiff rope, and the local diameter of the branch and the distance to its base and tip were measured. Compliance was negatively associated with both local diameter and length to the tip of the branch, and positively, if weakly, associated with length from the trunk. However, branch diameter not only predicted compliance best, but would also be easiest for an orangutan to observe. In contrast, oscillation times of branches were largely unaffected by local diameter, and only significantly increased at diameters below 2 cm. The results of this study validate previous field research, which related locomotory modes to local branch diameter, while suggesting how arboreal animals themselves sense their mechanical environment. [ABSTRACT FROM AUTHOR]

Published
2013
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31. Human-like external function of the foot, and fully upright gait, confirmed in the 3.66 million year old Laetoli hominin footprints by topographic statistics, experimental footprint-formation and computer simulation

Author

Crompton, Robin H., Pataky, Todd C., Savage, Russell, D'Août, Kristiaan, Bennett, Matthew R., Day, Michael H., Bates, Karl, Morse, Sarita, and Sellers, William I.

Abstract

It is commonly held that the major functional features of the human foot (e.g. a functional longitudinal medial arch, lateral to medial force transfer and hallucal (big-toe) push-off) appear only in the last 2 Myr, but functional interpretations of footbones and footprints of early human ancestors (hominins) prior to 2 million years ago (Mya) remain contradictory. Pixel-wise topographical statistical analysis of Laetoli footprint morphology, compared with results from experimental studies of footprint formation; foot-pressure measurements in bipedalism of humans and non-human great apes; and computer simulation techniques, indicate that most of these functional features were already present, albeit less strongly expressed than in ourselves, in the maker of the Laetoli G-1 footprint trail, 3.66 Mya. This finding provides strong support to those previous studies which have interpreted the G-1 prints as generally modern in aspect.

Published
2012
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32. The extraordinary athletic performance of leaping gibbons

Author

Channon, Anthony J., Usherwood, James R., Crompton, Robin H., Günther, Michael M., and Vereecke, Evie E.

Abstract

The distance that animals leap depends on their take-off angle and velocity. The velocity is generated solely by mechanical work during the push-off phase of standing-start leaps. Gibbons are capable of exceptional leaping performance, crossing gaps in the forest canopy exceeding 10 m, yet possess none of the adaptations possessed by specialist leapers synonymous with maximizing mechanical work. To understand this impressive performance, we recorded leaps of the gibbons exceeding 3.7 m. Gibbons perform more mass-specific work (35.4 J kg−1) than reported for any other species to date, accelerating to 8.3 ms−1in a single movement and redefining our estimates of work performance by animals. This energy (enough for a 3.5 m vertical leap) is 60 per cent higher than that achieved by galagos, which are renowned for their remarkable leaping performance. The gibbons' unusual morphology facilitates a division of labour among the hind limbs, forelimbs and trunk, resulting in modest power requirements compared with more specialized leapers.

Published
2012
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33. Stresses in human leg muscles in running and jumping determined by force plate analysis and from...

Author

Thorpe, Susannah K.S., Li, Yu, Crompton, Robin H., and Alexander, R. McNeill

Subjects
PHYSIOLOGICAL stress, MUSCLES
Abstract

Presents a study on the measurement of stresses exerted by human muscles and the use of magnetic resonance imaging (MRI) for such measurements. Importance of having knowledge about the physiological cross-sectional area of muscles for measurement; Description of MRI; How study was conducted; Results of study.

Published
1998
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34. Stride lengths, speed and energy costs in walking of Australopithecus afarensis: using evolutionary robotics to predict locomotion of early human ancestors

Author

Sellers, William I, Cain, Gemma M, Wang, Weijie, and Crompton, Robin H

Abstract

This paper uses techniques from evolutionary robotics to predict the most energy-efficient upright walking gait for the early human relative Australopithecus afarensis, based on the proportions of the 3.2 million year old AL 288-1 ‘Lucy’ skeleton, and matches predictions against the nearly contemporaneous (3.5–3.6 million year old) Laetoli fossil footprint trails. The technique creates gaits de novoand uses genetic algorithm optimization to search for the most efficient patterns of simulated muscular contraction at a variety of speeds. The model was first verified by predicting gaits for living human subjects, and comparing costs, stride lengths and speeds to experimentally determined values for the same subjects. Subsequent simulations for A. afarensisyield estimates of the range of walking speeds from 0.6 to 1.3ms−1at a cost of 7.0Jkg−1m−1for the lowest speeds, falling to 5.8Jkg−1m−1at 1.0ms−1, and rising to 6.2Jkg−1m−1at the maximum speed achieved. Speeds previously estimated for the makers of the Laetoli footprint trails (0.56 or 0.64ms−1for Trail 1, 0.72 or 0.75ms−1for Trail 2/3) may have been underestimated, substantially so for Trail 2/3, with true values in excess of 0.7 and 1.0ms−1, respectively. The predictions conflict with suggestions that A. afarensisused a ‘shuffling’ gait, indicating rather that the species was a fully competent biped.

Published
2005
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35. Factors Affecting the Compliance and Sway Properties of Tree Branches Used by the Sumatran Orangutan (Pongo abelii).

Author

van Casteren, Adam, Sellers, William I., Thorpe, Susannah K. S., Coward, Sam, Crompton, Robin H., and Ennos, A. Roland

Subjects
*TREE branches, *PONGO abelii, *PLANT habitats, *PLANT ecology, *COMPUTATIONAL biology
Abstract

The tropical arboreal environment is a mechanically complex and varied habitat. Arboreal inhabitants must adapt to changes in the compliance and stability of supports when moving around trees. Because the orangutan is the largest habitual arboreal inhabitant, it is unusually susceptible to branch compliance and stability and therefore represents a unique animal model to help investigate how animals cope with the mechanical heterogeneity of the tropical canopy. The aim of this study was to investigate how changes in compliance and time of oscillation of branches are related to easily observable traits of arboreal supports. This should help predict how supports react mechanically to the weight and mass of a moving orangutan, and suggest how orangutans themselves predict branch properties. We measured the compliance and time of oscillation of branches from 11 tree species frequented by orangutans in the rainforest of Sumatra. Branches were pulled at several points along their length using a force balance at the end of a stiff rope, and the local diameter of the branch and the distance to its base and tip were measured. Compliance was negatively associated with both local diameter and length to the tip of the branch, and positively, if weakly, associated with length from the trunk. However, branch diameter not only predicted compliance best, but would also be easiest for an orangutan to observe. In contrast, oscillation times of branches were largely unaffected by local diameter, and only significantly increased at diameters below 2 cm. The results of this study validate previous field research, which related locomotory modes to local branch diameter, while suggesting how arboreal animals themselves sense their mechanical environment. [ABSTRACT FROM AUTHOR]

Published
2013
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