A cadaveric study of wrist-joint moments in chimpanzees and orangutans with implications for the evolution of knuckle-walking

Bibliographic Data

ID5709348
AuthorsAkimasa Ito (The University of Tokyo, corresponding author), Masayuki Oishi (0000-0002-6308-6337, Azabu University), Motoharu Oishi, Hideki Endo (0000-0001-9158-618X, University of Tokyo Hospital), Eishi Hirasaki (0000-0001-7849-1936, Institut de Biologia Evolutiva), Naomichi Ogihara (0000-0002-1697-9263, The University of Tokyo, corresponding author)
Year2024
Volume197
Pages103600
Publication date2024-12-01
Peer ReviewedYes
Open AccessYes
TypeARTICLE
VenueJournal of Human Evolution (JOURNAL)
Journal identifiersISSN: 0047-2484 • E-ISSN: 1095-8606
PublisherElsevier BV (PUBLISHER)
DOI10.1016/j.jhevol.2024.103600
PMID39471655
OpenAlexW4403955874
LanguageEN
Citations received3
References cited54

Understanding the mechanism underlying the evolution of knuckle-walking in African great apes but not in humans may provide important implications about the origin and evolution of human bipedal locomotion. In this study, aiming to reveal possible structural adaptations of the chimpanzee's forearm and hand musculature related to knuckle-walking, we measure the passive elastic moment of the chimpanzee's and orangutan's wrist as it was rotated into extension, immobilizing the metacarpophalangeal joint at three different positions: extended (as in knuckle-walking), flexed (as in fist-walking), and an intermediate position. Our findings demonstrate that when the metacarpophalangeal joints are extended, the rigidity of the wrist joint in the extended direction increases. This increased rigidity is attributed to the passive elongation and force generation of digital flexor muscles, which are relatively short in chimpanzees. Consequently, this enhanced wrist-joint rigidity contributes to the stability and energetically efficient transmission of propulsive force to the ground during the stance phase. Overall, our study supports the hypothesis that knuckle-walking is an adaptation to terrestrial locomotion for an ancestor characterized by the restricted capacity for wrist extension owing to the relatively shorter tendons of digital flexor muscles

Cadaveric spasm · Joint (building) · Physical medicine and rehabilitation · Wrist · Action Observation and Synchronization · Anatomy · Engineering · Medicine · Motor Control and Adaptation · Primate Behavior and Ecology

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