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Communication Dans Un Congrès Année : 2019

First metacarpal trabecular morphology: Implications for thumb use in great apes and Australopithecus

Résumé

Fossil hominin thumb morphology is often compared to that of extant hominids, for which we have observed manual behaviors, to infer the locomotor and manipulative capabilities of extinct hominins. Preserved internal trabecular morphology can provide evidence for fossil hominin thumb use since it remodels in response to loading experienced during life. Here we use micro-CT data to analyze trabecular architecture of the first metacarpal in extant great apes (n= 41), early and recent Homo sapiens (n=13), Australopithecus africanus (StW 418), Australopithecus sediba (MH2), Paranthropus/early Homo (SK 84 and SKX 5020) and Homo neanderthalensis (n=3). We apply a geometric morphometric approach to the subarticular regions of ‘whole-epiphysis’ trabecular models, to test for significant differences in relative trabecular bone volume fraction and degree of anisotropy between species. Results indicate that H. sapiens have significantly different first metacarpal trabecular architecture from that of other extant hominids, consistent with abduction of the thumb during forceful pad-to-pad preci-sion grips. Great ape trabecular architecture is generally consistent with a habitually adducted thumb, used in pad-to-side and non-precision grips. Though, Neanderthal and MH2 trabecular morphology generally appears more similar to recent humans than extant apes, StW 418 demonstrates a more mosaic morphology, while SK 84 and SKX 5020 diverge further from the human pattern. These findings offer further insight into the manual behaviours of fossil hominins, as well as the adaptive shift from locomotor to manipulative hand use that occurred in our evolutionary history.

Dates et versions

hal-03970473 , version 1 (02-02-2023)

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Citer

Christopher J Dunmore, Tracy L Kivell, Nicholas B Stephens, Ameline Bardo, Matthew M Skinner, et al.. First metacarpal trabecular morphology: Implications for thumb use in great apes and Australopithecus. 88th Annual Meeting of the American Association of Physical Anthropologists (AAPA), Mar 2019, Cleveland, United States. pp.64-65, ⟨10.1002/ajpa.23802⟩. ⟨hal-03970473⟩

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