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.

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
katerina.harvati@ifu.uni-tuebingen.de
* 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"

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.

littor...@gmail.com 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