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Biomechanics of the Thumb and the Evolution of Human Dexterity

38 Pages Posted: 3 Sep 2020 Publication Status: Published

See all articles by Fotios-Alexandros Karakostis

Fotios-Alexandros Karakostis

University of Tuebingen - Department of Paleoanthropology

Daniel Haeufle

University of Tuebingen - Hertie Institute for Clinical Brain Research

Ioanna Anastopoulou

National and Kapodistrian University of Athens - Department of Forensic Medicine and Toxicology

Konstantinos Moraitis

National and Kapodistrian University of Athens - Department of Forensic Medicine and Toxicology

Gerhard Hotz

Natural History Museum of Basel - Anthropological Collection

Vangelis Tourloukis

University of Tuebingen - Department of Paleoanthropology

Katerina Harvati

University of Tuebingen - Department of Paleoanthropology

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Abstract

Tool use is one of humanity’s defining characteristics, possibly originating as early as > 3 million years ago. Although heightened manual dexterity is considered to be intrinsically intertwined with tool use and manufacture and critical for human evolution, its role in the emergence of early culture remains unclear. Most previous research on this question exclusively relied on direct morphological comparisons between early hominin and modern human skeletal elements, assuming that the degree of a species’ dexterity depends on its similarity with the modern human form. Here we develop a new approach to investigate the biomechanical efficiency of thumb opposition, a fundamental component of manual dexterity, in several species of fossil hominins. Our work for the first time takes into account soft tissue as well as bone anatomy, integrating virtual modeling of the muscle opponens pollicis and its interaction with three-dimensional bone shape form. Results indicate that efficient thumb opposition appeared approximately 2 million years ago, likely associated with our own genus Homo, and did not characterize Australopithecus, the earliest proposed stone tool-maker. This was true also of the late Australopithecus species, A. sediba, previously found to exhibit human-like thumb morphology. In contrast, later Homo species, including the small-brained H. naledi, show high levels of thumb opposition dexterity, highlighting the increasing importance of cultural processes and manual dexterity in later human evolution.

Keywords: biomechanical modelling, 3-D muscle modelling, muscle attachments, evolutionary biomechanics, functional morphology, evolution of tool use, hand

Suggested Citation

Karakostis, Fotios-Alexandros and Haeufle, Daniel and Anastopoulou, Ioanna and Moraitis, Konstantinos and Hotz, Gerhard and Tourloukis, Vangelis and Harvati, Katerina, Biomechanics of the Thumb and the Evolution of Human Dexterity. Available at SSRN: https://ssrn.com/abstract=3667138 or http://dx.doi.org/10.2139/ssrn.3667138
This version of the paper has not been formally peer reviewed.

Fotios-Alexandros Karakostis

University of Tuebingen - Department of Paleoanthropology ( email )

Germany

Daniel Haeufle

University of Tuebingen - Hertie Institute for Clinical Brain Research ( email )

Ioanna Anastopoulou

National and Kapodistrian University of Athens - Department of Forensic Medicine and Toxicology ( email )

5 Stadiou Strt
Athens, 12131
Greece

Konstantinos Moraitis

National and Kapodistrian University of Athens - Department of Forensic Medicine and Toxicology

5 Stadiou Strt
Athens, 12131
Greece

Gerhard Hotz

Natural History Museum of Basel - Anthropological Collection ( email )

Cromwell Road
London, SW7 5BD
United Kingdom

Vangelis Tourloukis

University of Tuebingen - Department of Paleoanthropology ( email )

Germany

Katerina Harvati (Contact Author)

University of Tuebingen - Department of Paleoanthropology ( email )

Germany

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