%0 Journal Article %A van Beesel, Julia %A Hutchinson, John R. %A Hublin, Jean-Jacques %A Melillo, Stephanie Marie %+ Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Max Planck Society The Leipzig School of Human Origins (IMPRS), Max Planck Institute for Evolutionary Anthropology, Max Planck Society Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Max Planck Society Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Max Planck Society %T Comparison of the arm‐lowering performance between Gorilla and Homo through musculoskeletal modeling : %G eng %U https://hdl.handle.net/21.11116/0000-000A-188C-E %R 10.1002/ajpa.24511 %7 2022-03-10 %D 2022 %* Review method: peer-reviewed %X Objectives:Contrary to earlier hypotheses, a previous biomechanical analysis indi-cated that long-documented morphological differences between the shoulders ofhumans and apes do not enhance the arm-raising mechanism. Here, we investigate adifferent interpretation: the oblique shoulder morphology that is shared by all homi-noids but humans enhances the arm-lowering mechanism.Materials and methods:Musculoskeletal models allow us to predict performancecapability to quantify the impact of muscle soft-tissue properties and musculoskeletalmorphology. In this study, we extend the previously published gorilla shoulder modelby adding glenohumeral arm-lowering muscles, then comparing the arm-loweringperformance to that of an existing human model. We further use the models to dis-entangle which morphological aspects of the shoulder affect arm-lowering capacityand result in interspecific functional differences.Results:Our results highlight that arm-lowering capacity is greater inGorillathan inHomo. The enhancement results from greater maximum isometric force capacitiesand moment arms of two important arm-lowering muscles, teres major, andpectoralis major. More distal muscle insertions along the humerus together with amore oblique shoulder configuration cause these greater moment arms.Discussion:The co-occurrence of improved arm-lowering capacity and high-muscleactivity at elevation angles used during vertical climbing highlight the importance of astrong arm-lowering mechanism for arboreal locomotor behavior in nonhuman apes.Therefore, our findings reveal certain skeletal shoulder features that are advanta-geous in an arboreal context. These results advance our understanding of adaptationin living apes and can improve functional interpretations of the hominin fossil record %K gorilla locomotion, hominoid shoulder, moment arm, musculoskeletal model, shoulderfunctional morphology %J American Journal of Biological Anthropology %V 178 %N 3 %& 399 %P 399 - 416 %I Wiley %@ 2692-7691