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  • Biomechanics of the human thumb and the evolution of dexterity

    From Primum Sapienti@21:1/5 to All on Sat Oct 14 22:23:10 2023
    https://www.cell.com/current-biology/fulltext/S0960-9822(20)31893-5
    Published: January 28, 2021

    Highlights
    * Increased thumb opposition efficiency was present
    about 2 million years ago
    * This evolutionary advantage was less pronounced in
    Australopithecus
    * This dexterity is shared with all recent hominins,
    including Homo naledi

    Summary
    Systematic tool production and 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 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 musculus opponens pollicis
    and its interaction with three-dimensional bone
    shape form. Results indicate that a fundamental
    aspect of efficient thumb opposition appeared
    approximately 2 million years ago, possibly
    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,
    Australopithecus sediba, previously found to
    exhibit human-like thumb proportions. In
    contrast, later Homo species, including the
    small-brained Homo naledi, show high levels of
    thumb opposition dexterity, highlighting the
    increasing importance of cultural processes
    and manual dexterity in later human evolution.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From [email protected]@21:1/5 to All on Sun Oct 15 12:57:46 2023
    Current Biology, Biomechanics of the human thumb and the evolution of dexterity F.A.Karakostis cs 2021 Curr.Biol.31:1317-1325 https://www.cell.com/current-biology/fulltext/S0960-9822(20)31893-5 [email protected]
    * Increased thumb opposition efficiency was present c 2 Ma.
    * This evolutionary advantage was less pronounced in Australopithecus.
    * This dexterity is shared with all recent hominins, incl.Homo naledi. Systematic tool production & use is one of humanity’s defining characteristics, possibly originating >3 Ma.
    Although heightened manual dexterity is considered to be intrinsically intertwined with tool use & 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 & 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 efficiency of thumb-opposition, a fundamental component of manual dexterity, in several spp of fossil hominins.
    Our work for the first time takes into account soft tissue & anatomy, integrating virtual modeling of musc.opponens pollicis & its interaction with 3D bone-shape.
    Results:
    a fundamental aspect of efficient thumb opposition appeared c 2 Ma, possibly ass.x our own genus Homo,
    it did not characterize Australopithecus, the earliest proposed stone tool maker.
    This was true also of the late Australopithecus species Au.sediba, previously found to exhibit human-like thumb proportions.
    In contrast, later Homo spp (incl. the small-brained H.naledi) show high levels of thumb opposition dexterity, highlighting the increasing importance of cultural processes & manual dexterity in later human evolution.

    ____

    :-) This beautifully confirms our view: australopiths were no tool-makers like Homo, see my 2022 book, google "Verhaegen Bonne English"

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From [email protected]@21:1/5 to All on Sun Oct 15 12:59:14 2023
    Op zondag 15 oktober 2023 om 06:23:17 UTC+2 schreef Primum Sapienti:

    :-) Thanks, my boy, this beautifully confirms our view, see my 2022 book, google e.g. "Verhaegen Bonne English".

    https://www.cell.com/current-biology/fulltext/S0960-9822(20)31893-5 Published: January 28, 2021
    Highlights
    * Increased thumb opposition efficiency was present
    about 2 million years ago
    * This evolutionary advantage was less pronounced in
    Australopithecus
    * This dexterity is shared with all recent hominins,
    including Homo naledi
    Systematic tool production and 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 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 musculus opponens pollicis
    and its interaction with three-dimensional bone
    shape form. Results indicate that a fundamental
    aspect of efficient thumb opposition appeared
    approximately 2 million years ago, possibly
    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,
    Australopithecus sediba, previously found to
    exhibit human-like thumb proportions. In
    contrast, later Homo species, including the
    small-brained Homo naledi, show high levels of
    thumb opposition dexterity, highlighting the
    increasing importance of cultural processes
    and manual dexterity in later human evolution.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From JTEM is so reasonable@21:1/5 to [email protected] on Sun Oct 15 20:18:39 2023
    [email protected] wrote:

    :-) Thanks, my boy, this beautifully confirms our view, see my 2022 book, google e.g. "Verhaegen Bonne English".

    Yeah. The human hand is the _Less_ derived. The ancestor to
    Chimps walked upright and had a hand that looked more like a
    humans than a Chimps.

    If you every have some time to kill, and want to watch them
    squirm, try to force them to incorporate this into their model.

    Oops! They don't have a model. By bad.




    -- --

    https://jtem.tumblr.com/post/730831540483932160

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)