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Abstract Jumping allows arboreal mammals to navigate disparate canopy supports. Existing research suggests that the long, mobile limbs of many small primates—including basal primate ancestors—facilitate arboreal jumping performance by extending centre of mass (CoM) excursion during push-off, while reducing forces applied to the support to potentially improve stability on narrow, compliant branches. We test this premise using force platform and micro-CT analyses to compare the biomechanical strategies and corresponding body morphology modulating vertical jumping performance in Cheirogaleus medius (N = 3), a small arboreal primate, and Tupaia belangeri (N = 3), a similarly-sized semi-arboreal/terrestrial treeshrew (close relative to primates). As predicted, to increase take-off velocity (the primary determinant of jump height), T. belangeri prioritized force production and high mechanical power. This power-focused strategy corresponds with larger attachments and longer moment arms for hip and knee extensors. In contrast, C. medius prioritized CoM excursion over a longer push-off duration, a strategy enabled by their greater hip joint mobility. The ability to minimize force production in C. medius supports hypotheses of frequent use of narrow, compliant supports during early primate evolution, allowing early primates to jump more effectively and safely in a small branch milieu.
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Ecomorphological correlates of grasping forces in strepsirrhine primates
Powerful digital grasping is essential for primates navigating arboreal environments and is often regarded as a defining characteristic of the order. However,in vivodata on primate grip strength are limited. In this study, we collected grasping data from the hands and feet of eleven strepsirrhine species to assess how ecomorphological variables—such as autopodial shape, laterality, body mass and locomotor mode—influence grasping performance. Additionally, we derived anatomical estimates of grip force from cadaveric material to determine whetherin vivoandex vivogrip strength measurements follow similar scaling relationships and how they correlate. Results show that bothin vivoand anatomical grip strength scale positively with body mass, though anatomical measures may overestimatein vivoperformance. Species with wider autopodia tend to exhibit higher grip forces, and forelimb grip forces exceed those of the hindlimbs. No lateralization in grip strength was observed. While strepsirrhine grip forces relative to their body weight are comparable to those of other primates and slightly exceed those of humans, they are not exceptional compared to other arboreal mammals or birds, suggesting that claims of extraordinary primate grasping abilities require further investigation.
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- Award ID(s):
- 2314898
- PAR ID:
- 10617881
- Publisher / Repository:
- Proceedings of the Royal Society B: Biological Sciences
- Date Published:
- Journal Name:
- Proceedings of the Royal Society B: Biological Sciences
- Volume:
- 292
- Issue:
- 2039
- ISSN:
- 1471-2954
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1098/rspb.2024.2190
