Elephants evolved strategies reducing the biomechanical complexity of their trunk

Article Article scientifique Article Elephants evolved strategies reducing the biomechanical complexity of their trunk eng 2021-11 author Dagenais Paule 932862 author Hensman Sean author Haechler Valérie Isabelle Anna 911277 Département de génétique et évolution (Genev) (BIANI) author Milinkovitch Michel C. 679786 Département de génétique et évolution (Genev) (BIANI) 4727-4737.e4 10.1016/j.cub.2021.08.029 34428468 0960-9822 https://linkinghub.elsevier.com/retrieve/pii/S0960982221011337 <p>The elephant <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/proboscis" rel="noopener noreferrer" target="_blank">proboscis</a> (trunk), which functions as a muscular hydrostat with a virtually infinite number of degrees of freedom, is a spectacular organ for delicate to heavy <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/object-manipulation" rel="noopener noreferrer" target="_blank">object manipulation</a> as well as social and sensory functions. Using high-resolution motion capture and <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/functional-morphology" rel="noopener noreferrer" target="_blank">functional morphology</a> analyses, we show here that elephants evolved strategies that reduce the biomechanical complexity of their trunk. Indeed, our behavioral experiments with objects of various shapes, sizes, and weights indicate that (1) complex <a href="https://www.sciencedirect.com/topics/neuroscience/behavior-neuroscience" rel="noopener noreferrer" target="_blank">behaviors</a> emerge from the combination of a finite set of basic movements; (2) curvature, torsion, and strain provide an appropriate kinematic representation, allowing us to <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/extract" rel="noopener noreferrer" target="_blank">extract</a> motion primitives from the trunk trajectories; (3) transport of objects involves the proximal propagation of an inward curvature front initiated at the tip; (4) the trunk can also form pseudo-joints for point-to-point motion; and (5) the trunk tip velocity obeys a power law with its path curvature, similar to human hand drawing movements. We also reveal with unprecedented precision the functional anatomy of the African and Asian elephant trunks using medical imaging and macro-scale serial sectioning, thus drawing strong connections between motion primitives and muscular synergies. Our study is the first combined <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/quantitative-technique" rel="noopener noreferrer" target="_blank">quantitative analysis</a> of the mechanical performance, kinematic strategies, and functional morphology of the largest animal muscular hydrostat on Earth. It provides data for developing innovative “soft-robotic” manipulators devoid of articulations, replicating the high compliance, flexibility, and <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/strength" rel="noopener noreferrer" target="_blank">strength</a> of the elephant trunk.</p> Bioinspiration Biomechanics Elephant trunk Functional anatomy Motion primitives Muscular hydrostat Prehension strategies Proboscis Pseudo-joints Speed-curvature power law Dewey 590 European Commission Proboscidean sensitive soft robot for versatile gripping 863212 PROBOSCIS EU H2020 44 Département de génétique et évolution 162 false Current biology 31 21 8b9967f0-a21e-4687-947c-043d013799f6 Article (Published version) Public Article-scientifique-from-unpaywall.pdf 3623595 application/pdf CC BY-4.0 f1992c97159fd5a8def333cfc3eebcfe7a056ab6b014d47d1b3966f4e38d31c0 openAccess Faculté des sciences / Section de biologie / Département de génétique et évolution

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Elephants evolved strategies reducing the biomechanical complexity of their trunk	Current biology			2021	36	53

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Dagenais, Paule