Programmes > Par auteur > Kivell Tracy L

Morpho-functional characteristics of the Neanderthal thumb: implications for their diverse tool kit
Ameline Bardo  1@  , Marie-Hélène Moncel  2@  , Tracy L Kivell  1, 3@  , Emmanuelle Pouydebat  4@  , Raphaël Cornette  5@  
1 : Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent  -  Site web
Canterbury, Kent, CT2 7NR, United Kingdom -  Royaume-Uni
2 : Department of Homme et environnement, UMR7194–HNHP  (CNRS – MNHN – UPVD – Sorbonne Universités)  -  Site web
UMR 7194
3 : Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology
D-04103 Leipzig, Germany -  Allemagne
4 : Department of Adaptations du vivant, UMR 7179, Mécanismes adaptatifs, des organismes aux communautés  (CNRS-MNHN, MECADEV)  -  Site web
UMR 7179
Pavillon d'anatomie comparée, 55 rue Buffon, case postale 55, 75231 Paris cedex 5. -  France
5 : Institut de Systématique, Evolution, Biodiversité  (CNRS/MNHN/UPMC/EPHE, ISYEB)  -  Site web
CNRS : UMR7205

Variation in fossil hominin (human) hand morphology has played a key role in the interpretation of the evolution of human manipulative abilities. In particular, there has been a specific focus on thumb morphology and how it might reflect the functional requirements of tool-related behaviours. To better understand the morphological transitions that lead to the anatomically modern human (Homo sapiens) hand, many studies have analysed how it differs from that of Neanderthals (Homo neanderthalensis). Morpho-functional interpretations generally agree that although both modern humans and Neanderthals were likely capable of the same precise dexterity, Neanderthal hands appear better adapted for forceful power grips that are considered important for tool-related activities. Neanderthals used high diversity of tools from micro-flakes (10-15 mm long) to large flakes (around 15 cm long), and previous studies suggested that this diversity was an intentional choice. However, why Neanderthals used microlithic tools, and how these tools could be held in their hand remains unknown. To better understand how the Neanderthal and H. sapiens thumb may have varied in their function, it is important to evaluate the functional interaction between the trapezium and the first metacarpal, as together they determine the joint mobility of the thumb. Moreover, as bone continues to remodel throughout life, it may record constraints related to manual activity. Here we use 3D surface geometric morphometrics to investigate for the first time shape variation and co-variation between all of the joints of the trapezium and the first metacarpal across a large sample of modern humans, early and late Upper Palaeolithic humans, and Neanderthals with associated trapezium and first metacarpals. Results show that both early and modern H. sapiens cluster together with the same morphological distribution, while Neanderthals, and particularly Kebara 2, are distinct from them, indicating specific joint shape and orientation that differs between Neanderthals and H. sapiens. Moreover, each Neanderthal specimen shows specific shape co-variation with higher intra-individual variability than that H. sapiens, suggesting different morpho-functional constraints within Neanderthals. We hypothesize that these different morphologies among Neanderthals could be correlated with a behavioural variability linked with different cultures, with maybe different manual techniques used during tool-related activities compared with H. sapiens.

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