Cutting corners: The dynamics of turning behaviors in two primate species

Department of Anatomical Sciences, Stony Brook University, NY 11794-8081, USA.
Journal of Experimental Biology (Impact Factor: 2.9). 04/2006; 209(Pt 5):927-37. DOI: 10.1242/jeb.02046
Source: PubMed

ABSTRACT In an attempt to characterize more fully the variation in substrate reaction forces in the locomotor repertoire of primates, we recorded the forces involved in directional changes for two species. These are the first records of turning forces for vertebrate quadrupeds, much less primates. Three ring-tailed lemurs and two patas monkeys performed turns of approximately 30 degrees as they crossed a force platform. The ring-tailed lemurs also turned on a horizontal branch-like support with a segment attached to the force transducer. Mediolateral forces of up to 40% body weight were recorded. These are considerably higher than during linear locomotion. Pivot limbs in ground turns and turns on the branch differed in the lemurs, suggesting that substrate influences turning strategies. Limbs encountered both medial and lateral reaction forces, and as a result, they may be exposed to variable bending regimes in the frontal plane. The stereotypy in bending regimes suggested by in vivo bone strain studies, therefore, may characterize linear locomotion only. The lemurs showed hindlimb dominance in turns, both in terms of frequency used as well as force magnitude (hindlimb steering). Hindlimb dominance in weight support characterizes both species (and primates in general), but it is more pronounced in the lemurs. In the patas monkeys, forces were more evenly distributed among the two pairs of limbs. The mediolateral turning forces therefore seem to track the amount of weight to be shifted sideways. Overall variance in mediolateral forces was greater in the arboreal and versatile lemurs than in the terrestrial and cursorial patas monkeys.

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Available from: Kristian J Carlson, Sep 27, 2015
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    • "Fortunately, this has now been widely acknowledged and we are seeing more and more studies that focus on nonlinear and unsteady locomotion (Walter 2003; Demes et al. 2006; Carlson and Judex 2007; Moreno et al. 2008; Walter and Carrier 2009; Demes and Carlson 2009). "
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    ABSTRACT: Most of our knowledge regarding primate locomotion, especially biomechanical aspects, results from studies of captive populations, typically in laboratories or zoos. Obviously, a controlled environment facilitates the acquisition of high-quality locomotion data; it has done so in the past and will continue to do so in the future. We start by outlining how primate locomotion has been studied in captive settings, and the sort of insights such studies have yielded. We draw examples from our own research on hylobatids (Hylobates lar, Symphalangus syndactylus) and bonobos (Pan paniscus), carried out using integrated setups in a zoo environment. Locomotion is highly variable in these hominoid species; even in a captive setup, it is inevitably less complex than in the natural habitat. Neither species uses a human-like stiff-legged (inverted pendulum) type of terrestrial locomotion. Bonobos use a highly crouched posture both in bipedal and quadrupedal terrestrial locomotion; lar gibbons use a bouncing gait with potential for energy saving mechanisms in the knee and in the foot. Aspects of arboreal locomotion have been, or are being studied in the three species, using stiff substrates and overhead supports. Next, we discuss some shortcomings of working outside of the natural habitat, ex situ. They pertain most clearly to the limited number of subjects (a result of availability issues and the high level of detail required) and to the relative lack of complexity in the substrates used. Especially during arboreal locomotion, new research lines should be (and are being) started in which spatial complexity and compliance are incorporated in the experimental setup. We are currently using this approach to study jumping off branches and for brachiation in hylobatids. Finally, we make some suggestions of how field work can help meet some of the limitations intrinsic to ex situ studies. Locomotor field studies are complementary to ex situ studies in their capacity to study larger sample sizes (albeit in lesser detail) in their natural environment, thereby documenting, preferably quantitatively, the natural locomotion repertoire, unbiased by human-made setups. Specifically, field studies are crucial for describing the locomotor modes that are actually used by the species studied, and for providing an ecological framework for an integrated approach of primate locomotion. Keywordsbiomechanics-bipedalism-bonobo-captive-gibbon-Hominidae-locomotion-quadrupedalism-techniques-wild
    01/2011: pages 29-46;
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    • "In addition to potential community-level differences between the percentage of locomotion in arboreal and terrestrial settings, qualitative differences within terrestrial quadrupedalism at the communities might be possible to infer, if morphological trends are assessed in the context of ecological trends. Based on the effect that changes in direction have on mediolateral external forces (Demes et al. 2006) and bony morphology (Carlson and Judex 2007), Carlson et al. (2008) proposed that chimpanzees occupying more densely forested habitats may experience greater side-to-side forces during terrestrial quadrupedalism compared to chimpanzees occupying less densely forested habitats, which may further enhance the disparity between ML rigidity and AP rigidity in diaphyseal cross sections. The ultimate result in this case could be more elliptical diaphyses in chimpanzees inhabiting denser forested habitats . "
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    ABSTRACT: Structural characteristics of limb bones provide insight into how an animal dynamically loads its limbs during life. Cause-and-effect relationships between loading and the osteogenic response it elicits are complex. In spite of such complexities, cross-sectional geometric properties can be useful indicators of locomotor repertoires. Typical comparisons use primates that are distinguished by broad habitual locomotor differences, usually with samples garnered from several museum collections. Intraspecific variability is difficult to investigate in such samples because knowledge of their behavior or life histories, which are tools for interpreting intraspecific variability, is limited. Clearly, intraspecific variation both in morphology and behavior/life history exists. Here we expand an ongoing effort toward understanding intraspecific variation in limb structural properties by comparing free-ranging chimpanzees that have associated behavioral and life history data. Humeral and femoral data from 11 adult chimpanzees (Pan troglodytes) of Kibale National Park (Uganda) are compared to 29 adult chimpanzees from Gombe (Tanzania), Mahale Mountains (Tanzania), and Taï Forest (Côte d’Ivoire) National Park communities. Overall, limb structural morphology of Kibale chimpanzees most resembles limb structural morphology of Mahale chimpanzees. Shape ratios and percentage cortical areas of Kibale chimpanzees are most similar to non-Gombe chimpanzees, while Kibale structural properties, e.g., maximum rigidity, are most similar to non-Taï structural properties. Even after adding Kibale females, Taï females continue to stand out from females in other communities. KeywordsCross-sectional geometry-Functional morphology-Locomotor ­behavior- Pan troglodytes
    01/2011: pages 155-182;
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    • "To capture the loads associated with locomotion in a natural habitat, our efforts should clearly be focused on trying to expand the range of activities solicited in a laboratory experimental environment. Nonlinear locomotion is a particularly important activity that has been widely neglected in vertebrate locomotor studies (but see Burr et al., 1996; Walter, 2003; Demes et al., 2006; Carlson and Judex, 2007; Jindrich et al., 2007; Moreno et al., 2008). The advice by Dickinson et al. (2000) to ''leave the straight and narrow'' in laboratory studies of locomotion is still highly relevant. "
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    ABSTRACT: Primates are very versatile in their modes of progression, yet laboratory studies typically capture only a small segment of this variation. In vivo bone strain studies in particular have been commonly constrained to linear locomotion on flat substrates, conveying the potentially biased impression of stereotypic long bone loading patterns. We here present substrate reaction forces (SRF) and limb postures for capuchin monkeys moving on a flat substrate ("terrestrial"), on an elevated pole ("arboreal"), and performing turns. The angle between the SRF vector and longitudinal axes of the forearm or leg is taken as a proxy for the bending moment experienced by these limb segments. In both frontal and sagittal planes, SRF vectors and distal limb segments are not aligned, but form discrepant angles; that is, forces act on lever arms and exert bending moments. The positions of the SRF vectors suggest bending around oblique axes of these limb segments. Overall, the leg is exposed to greater moments than the forearm. Simulated arboreal locomotion and turns introduce variation in the discrepancy angles, thus confirming that expanding the range of locomotor behaviors studied will reveal variation in long bone loading patterns that is likely characteristic of natural locomotor repertoires. "Arboreal" locomotion, even on a linear noncompliant branch, is characterized by greater variability of force directions and discrepancy angles than "terrestrial" locomotion (significant for the forearm only), partially confirming the notion that life in trees is associated with greater variation in long bone loading. Directional changes broaden the range of external bending moments even further.
    American Journal of Physical Anthropology 08/2009; 139(4):558-71. DOI:10.1002/ajpa.21020 · 2.38 Impact Factor
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