https://phys.org/news/2021-08-humans-ditched-swiveling-hips-shorter.html

The loss of the ‘pelvic step’ in human evolution

ABSTRACT

Human bipedalism entails relatively short strides compared with
facultatively bipedal primates. Unique non-sagittal-plane motions
associated with bipedalism may account for part of this discrepancy.
Pelvic rotation anteriorly translates the hip, contributing to bipedal
stride length (i.e. the ‘pelvic step’). Facultative bipedalism in
non-human primates entails much larger pelvic rotation than in humans,
suggesting that a larger pelvic step may contribute to their
relatively longer strides. We collected data on the pelvic step in
bipedal chimpanzees and over a wide speed range of human walking. At
matched dimensionless speeds, humans have 26.7% shorter dimensionless
strides, and a pelvic step 5.4 times smaller than bipedal chimpanzees.
Differences in pelvic rotation explain 31.8% of the difference in
dimensionless stride length between the two species. We suggest that
relative stride lengths and the pelvic step have been significantly
reduced throughout the course of hominin evolution.

https://doi.org/10.1242/jeb.240440

It would appear that Australopithecus afarensis ("Lucy") still had
this pelivic step, indicating a distinctly different kind of
bipedalism at this stage compared to Homo:

https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.23550

> https://phys.org/news/2021-08-humans-ditched-swiveling-hips-shorter.html
> The loss of the ‘pelvic step’ in human evolution

Beautiful study, thanks, but we didn't lose anything:
chimps evolved their "pelvic step", just like they evolved much longer ilia..

The usual anthropocentric interpretation...

Google "aquarboreal" or
"ape human evolution made easy PPT verhaegen".

> Human bipedalism entails relatively short strides compared with
> facultatively bipedal primates. Unique non-sagittal-plane motions
> associated with bipedalism may account for part of this discrepancy.
> Pelvic rotation anteriorly translates the hip, contributing to bipedal
> stride length (i.e. the ‘pelvic step’). Facultative bipedalism in
> non-human primates entails much larger pelvic rotation than in humans,
> suggesting that a larger pelvic step may contribute to their
> relatively longer strides. We collected data on the pelvic step in
> bipedal chimpanzees and over a wide speed range of human walking. At
> matched dimensionless speeds, humans have 26.7% shorter dimensionless
> strides, and a pelvic step 5.4 times smaller than bipedal chimpanzees.
> Differences in pelvic rotation explain 31.8% of the difference in
> dimensionless stride length between the two species. We suggest that
> relative stride lengths and the pelvic step have been significantly
> reduced throughout the course of hominin evolution.
> https://doi.org/10.1242/jeb.240440 >
> It would appear that Australopithecus afarensis ("Lucy") still had
> this pelvic step, indicating a distinctly different kind of
> bipedalism at this stage compared to Homo
> https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.23550

On 21.8.2021. 13:20, littor...@gmail.com wrote:
>> https://phys.org/news/2021-08-humans-ditched-swiveling-hips-shorter.html
>> The loss of the ‘pelvic step’ in human evolution
>
> Beautiful study, thanks, but we didn't lose anything:
> chimps evolved their "pelvic step", just like they evolved much longer ilia.
>
> The usual anthropocentric interpretation...
>
> Google "aquarboreal" or
> "ape human evolution made easy PPT verhaegen".

Hm, abracadabra.

>> Human bipedalism entails relatively short strides compared with
>> facultatively bipedal primates. Unique non-sagittal-plane motions
>> associated with bipedalism may account for part of this discrepancy.
>> Pelvic rotation anteriorly translates the hip, contributing to bipedal
>> stride length (i.e. the ‘pelvic step’). Facultative bipedalism in
>> non-human primates entails much larger pelvic rotation than in humans,
>> suggesting that a larger pelvic step may contribute to their
>> relatively longer strides. We collected data on the pelvic step in
>> bipedal chimpanzees and over a wide speed range of human walking. At
>> matched dimensionless speeds, humans have 26.7% shorter dimensionless
>> strides, and a pelvic step 5.4 times smaller than bipedal chimpanzees.
>> Differences in pelvic rotation explain 31.8% of the difference in
>> dimensionless stride length between the two species. We suggest that
>> relative stride lengths and the pelvic step have been significantly
>> reduced throughout the course of hominin evolution.
>> https://doi.org/10.1242/jeb.240440 >
>> It would appear that Australopithecus afarensis ("Lucy") still had
>> this pelvic step, indicating a distinctly different kind of
>> bipedalism at this stage compared to Homo
>> https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.2355
--
https://groups.google.com/g/human-evolution
human-evolution@googlegroups.com

On Saturday, August 21, 2021 at 6:12:23 AM UTC-4, Pandora wrote:
> https://phys.org/news/2021-08-humans-ditched-swiveling-hips-shorter.html
>
> The loss of the ‘pelvic step’ in human evolution
>
> ABSTRACT
>
> Human bipedalism entails relatively short strides compared with
> facultatively bipedal primates. Unique non-sagittal-plane motions
> associated with bipedalism may account for part of this discrepancy.
> Pelvic rotation anteriorly translates the hip, contributing to bipedal
> stride length (i.e. the ‘pelvic step’). Facultative bipedalism in
> non-human primates entails much larger pelvic rotation than in humans,
> suggesting that a larger pelvic step may contribute to their
> relatively longer strides. We collected data on the pelvic step in
> bipedal chimpanzees and over a wide speed range of human walking. At
> matched dimensionless speeds, humans have 26.7% shorter dimensionless
> strides, and a pelvic step 5.4 times smaller than bipedal chimpanzees.
> Differences in pelvic rotation explain 31.8% of the difference in
> dimensionless stride length between the two species. We suggest that
> relative stride lengths and the pelvic step have been significantly
> reduced throughout the course of hominin evolution.
>
> https://doi.org/10.1242/jeb.240440
> https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.23550
- Compared to Homo sapien's & hylobatid's obligate orthograde flat-terrain striding gait, but archaic Homo had intermediate gait ('waddling stride') with the counter-balance (anchor point) being at the rear-skull occipital bone rather than the boney chin in modern Homo sapiens and hylobatids.

On Saturday, August 21, 2021 at 8:26:09 AM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:
> On Saturday, August 21, 2021 at 6:12:23 AM UTC-4, Pandora wrote:
> > https://phys.org/news/2021-08-humans-ditched-swiveling-hips-shorter.html
> >
> > The loss of the ‘pelvic step’ in human evolution
> >
> > ABSTRACT
> >
> > Human bipedalism entails relatively short strides compared with
> > facultatively bipedal primates. Unique non-sagittal-plane motions
> > associated with bipedalism may account for part of this discrepancy.
> > Pelvic rotation anteriorly translates the hip, contributing to bipedal
> > stride length (i.e. the ‘pelvic step’). Facultative bipedalism in
> > non-human primates entails much larger pelvic rotation than in humans,
> > suggesting that a larger pelvic step may contribute to their
> > relatively longer strides. We collected data on the pelvic step in
> > bipedal chimpanzees and over a wide speed range of human walking. At
> > matched dimensionless speeds, humans have 26.7% shorter dimensionless
> > strides, and a pelvic step 5.4 times smaller than bipedal chimpanzees.
> > Differences in pelvic rotation explain 31.8% of the difference in
> > dimensionless stride length between the two species. We suggest that
> > relative stride lengths and the pelvic step have been significantly
> > reduced throughout the course of hominin evolution.
> >
> > https://doi.org/10.1242/jeb.240440
> > https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.23550
> -
> Compared to Homo sapien's & hylobatid's obligate orthograde flat-terrain striding gait, but archaic Homo had intermediate gait ('waddling stride') with the counter-balance (anchor point) being at the rear-skull occipital bone rather than the boney chin in modern Homo sapiens and hylobatids.
---

The Hs stride came about later as a result of walking when we returned to a terrestrial existence. Another reason to suppose that chimp ancestors were already bipedal is that they went from quadrupedal primates -> orthograde aquarboreal apes --> wading hominids --(Pan/Homo split) --> Pan = knucklewalkers / Homo = swimmer /divers. There's no reason to go from plantigrade quadrupedalism to knuckle-walking unless you go through a transitional upright stage first.
F.
Hide quoted text
On 21/8/2021 2:58 μ.μ., Marc Verhaegen wrote:
Humans ditched swivelling hips for shorter stride than chimps
Kathryn Knight 2021
https://doi.org/10.1242/jeb.243185

.... compared with the strides of chimps, even the tallest Hs take rel.short steps:
Nathan Thompson (NY Inst.Technol.):
"standardized by size, humans really don't have long strides."
Until recently, most scientists (yes, unfortunately still most PAs... --mv) believed that the human stride was rel.long for efficiency:
"this is taught in almost every introductory class & textbook", although the misconception only became truly apparent when he began delving into the literature.
When Thompson began investigating how far chimps rotate their pelvises as they walk, he began wondering:
could swivelling their hips hold the key to their longer strides? He decided to compare chimp & human walking over a range of different speeds:
does the pelvis rotation provide the chimp's longer stride?

"Working with people and animals always has its difficulties." Thompson familiarised the chimps with walking upright on 2 feet while they filmed the animals in 3D.
Even working with the human walkers wasn't without its challenges:
one volunteer kept getting fits of the giggles because walking in bare feet on the treadmill felt weird:
"they couldn't help but walk in a totally bizarre way."

Once they reconstructed the human's stride pattern & hip motions in 3D, they the humans down to chimp size:
- although Hs legs were proportionally 112 % longer, their strides were 26.7 % shorter,
- the chimps swivelled their hips between 28° & 61° (vs Hs ∼8°).
When they checked how much further the pelvic rotation got them in terms of stride length, the chimps had a distinct advantage:
their swivelling hips extended their stride 5.4 x more (vs their size) than the human's diminutive swivel.

Thompson:
"IMO chimps use pelvic rotations to try to squeeze every bit of stride length out, otherwise their strides would be – absolutely – very small":
apes & monkeys tend to walk on crouched legs, that naturally shorten their stride:
"I don't think there are a lot of options other than rotating the pelvis, given their anatomical constraints."

But why have humans ditched swivelling their hips when it could extend their strides further?
Thompson suggests:
extreme rotations of the hips could throw out the natural swing of our arms & legs (which counterbalance each other) forcing our muscles to work harder, making walking less efficient: a price that simply might not be worth paying for an increased stride length:
scientists had thought for decades that Hs had evolved the longest possible stride for efficiency,
but now it turns out: our stride is considerably shorter <chimps:
other factors have had a larger impact on the way we walk:
"Hs have had c 7 Ma of selective pressure for economical BPism:
there has been a lot of time to experiment with the costs & benefits,
so it might be worth it to walk with slightly shorter strides, because whatever energy we lose, we might make up elsewhere."

(obviously, the experiment is excellent, but the interpretation is the traditional anthropocentrism,
the solution is not so difficult IMO:
- chimps evolved from aquarboreals to knuckle-walkers,
- we evolved to shallow-divers & then waders --mv) aat.io
---
If I have time, I will review this for errors or fantasies.

On Saturday, August 21, 2021 at 3:08:45 PM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:
> On Saturday, August 21, 2021 at 8:26:09 AM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:
> > On Saturday, August 21, 2021 at 6:12:23 AM UTC-4, Pandora wrote:
> > > https://phys.org/news/2021-08-humans-ditched-swiveling-hips-shorter.html
> > >
> > > The loss of the ‘pelvic step’ in human evolution
> > >
> > > ABSTRACT
> > >
> > > Human bipedalism entails relatively short strides compared with
> > > facultatively bipedal primates. Unique non-sagittal-plane motions
> > > associated with bipedalism may account for part of this discrepancy.
> > > Pelvic rotation anteriorly translates the hip, contributing to bipedal
> > > stride length (i.e. the ‘pelvic step’). Facultative bipedalism in
> > > non-human primates entails much larger pelvic rotation than in humans,
> > > suggesting that a larger pelvic step may contribute to their
> > > relatively longer strides. We collected data on the pelvic step in
> > > bipedal chimpanzees and over a wide speed range of human walking. At
> > > matched dimensionless speeds, humans have 26.7% shorter dimensionless
> > > strides, and a pelvic step 5.4 times smaller than bipedal chimpanzees..
> > > Differences in pelvic rotation explain 31.8% of the difference in
> > > dimensionless stride length between the two species. We suggest that
> > > relative stride lengths and the pelvic step have been significantly
> > > reduced throughout the course of hominin evolution.
> > >
> > > https://doi.org/10.1242/jeb.240440
> > > https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.23550
> > -
> > Compared to Homo sapien's & hylobatid's obligate orthograde flat-terrain striding gait, but archaic Homo had intermediate gait ('waddling stride') with the counter-balance (anchor point) being at the rear-skull occipital bone rather than the boney chin in modern Homo sapiens and hylobatids.
> ---
>
> The Hs stride came about later as a result of walking when we returned to a terrestrial existence. Another reason to suppose that chimp ancestors were already bipedal is that they went from quadrupedal primates -> orthograde aquarboreal apes --> wading hominids --(Pan/Homo split) --> Pan = knucklewalkers / Homo = swimmer /divers. There's no reason to go from plantigrade quadrupedalism to knuckle-walking unless you go through a transitional upright stage first.
> F.
> Hide quoted text
> On 21/8/2021 2:58 μ.μ., Marc Verhaegen wrote:
> Humans ditched swivelling hips for shorter stride than chimps
> Kathryn Knight 2021
> https://doi.org/10.1242/jeb.243185
>
> ... compared with the strides of chimps, even the tallest Hs take rel.short steps:
> Nathan Thompson (NY Inst.Technol.):
> "standardized by size, humans really don't have long strides."
> Until recently, most scientists (yes, unfortunately still most PAs... --mv) believed that the human stride was rel.long for efficiency:
> "this is taught in almost every introductory class & textbook", although the misconception only became truly apparent when he began delving into the literature.
> When Thompson began investigating how far chimps rotate their pelvises as they walk, he began wondering:
> could swivelling their hips hold the key to their longer strides? He decided to compare chimp & human walking over a range of different speeds:
> does the pelvis rotation provide the chimp's longer stride?
>
> "Working with people and animals always has its difficulties." Thompson familiarised the chimps with walking upright on 2 feet while they filmed the animals in 3D.
> Even working with the human walkers wasn't without its challenges:
> one volunteer kept getting fits of the giggles because walking in bare feet on the treadmill felt weird:
> "they couldn't help but walk in a totally bizarre way."
>
> Once they reconstructed the human's stride pattern & hip motions in 3D, they the humans down to chimp size:
> - although Hs legs were proportionally 112 % longer, their strides were 26.7 % shorter,
> - the chimps swivelled their hips between 28° & 61° (vs Hs ∼8°).
> When they checked how much further the pelvic rotation got them in terms of stride length, the chimps had a distinct advantage:
> their swivelling hips extended their stride 5.4 x more (vs their size) than the human's diminutive swivel.
>
> Thompson:
> "IMO chimps use pelvic rotations to try to squeeze every bit of stride length out, otherwise their strides would be – absolutely – very small":
> apes & monkeys tend to walk on crouched legs, that naturally shorten their stride:
> "I don't think there are a lot of options other than rotating the pelvis, given their anatomical constraints."
>
> But why have humans ditched swivelling their hips when it could extend their strides further?
> Thompson suggests:
> extreme rotations of the hips could throw out the natural swing of our arms & legs (which counterbalance each other) forcing our muscles to work harder, making walking less efficient: a price that simply might not be worth paying for an increased stride length:
> scientists had thought for decades that Hs had evolved the longest possible stride for efficiency,
> but now it turns out: our stride is considerably shorter <chimps:
> other factors have had a larger impact on the way we walk:
> "Hs have had c 7 Ma of selective pressure for economical BPism:
> there has been a lot of time to experiment with the costs & benefits,
> so it might be worth it to walk with slightly shorter strides, because whatever energy we lose, we might make up elsewhere."
>
>
> (obviously, the experiment is excellent, but the interpretation is the traditional anthropocentrism,
> the solution is not so difficult IMO:
> - chimps evolved from aquarboreals to knuckle-walkers,
> - we evolved to shallow-divers & then waders --mv) aat.io
> ---

Knuckle-walking could just as well be from descending from earlier brachiating apes, whose forelimbs had adapted to grab and hang from branches, like gibbons still do. Making such a transition from the canopy to the forest floor could then solicit adapting those grabbing forelimbs to walk on your knuckles instead.

https://www.natureplprints.com/p/729/northern-white-cheeked-gibbon-nomascus-19713898.jpg
https://upload.wikimedia.org/wikipedia/commons/thumb/a/a7/Western_Lowland_Gorilla.jpg/1200px-Western_Lowland_Gorilla.jpg
ce aat.io
-

> If I have time, I will review these claims for errors or fantasies.

-

on Elaine: And then there came three men, Ernst Mayr, George Gaylord Simpson, and Theodosius Dobzhansky. And they got together and they wrote a book called The New Synthesis. And they said: "There is no point in arguing who's right, Darwin or Mendel. They were both right and with a bit of trouble we can get them fused into a new synthesis." And by next year, in the course of next year, we should be able to do the same thing, get a new synthesis which fuses Darwin and Mendel and Hardy. And then we will explain why we are so different. As it is now, when the creationists say: "Well, if man was not a special creation, why is he so different from the others?" We've got to say: "I don't know." But if we have this synthesis, we can say: "I know why we are so different: because he is the only creature who has passed through a stage of arboreal behaviour, followed by a stage of semiaquatic behaviour, and a blend of these two makes a lot of things possible, that have never been possible before."

Not aquamarine, not aquarboreal, not coastal: rainforest arboreal along shallow crystalline streams -> rainforest terrestrial along shallow crystalline streams -> expansion to coasts & savannas (?).
-

Lucy was no human ancestor, of course:
most likely, it was a fossil relative of gorillas.
Google:
"Australopithecines: Ancestors of the African Apes?"

IOW, we didn't lose it,
but chimps evolved the "pelvic step".

> https://phys.org/news/2021-08-humans-ditched-swiveling-hips-shorter.html
The loss of the ‘pelvic step’ in human evolution

Human BPism entails rel.short strides vs facultatively BP primates.
Unique non-sagittal-plane motions ass.x BPism may account for part of this discrepancy.
Pelvic rotation anteriorly translates the hip, contributing to BP stride length (i.e. the ‘pelvic step’).
Facultative BPism in non-human primates entails much larger pelvic rotation than in Hs:
does a larger pelvic step contribute to their rel.longer strides?
We collected data on the pelvic step in BP chimps & over a wide speed range of human walking.
At matched dimensionless speeds, Hs have
- 26.7 % shorter dimensionless strides,
- a pelvic step 5.4 x smaller than BP chimps.
Differences in pelvic rotation explain 31.8 % of the difference in dimensionless stride length between the 2 spp.
We suggest:
relative stride lengths & the pelvic step have been significantly reduced throughout the course of hominin evolution.

https://doi.org/10.1242/jeb.240440

It would appear that Au.afarensis Lucy still had this pelvic step: a distinctly different kind of BPism at this stage vs Homo:
https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.23550

Pelvic Breadth and Locomotor Kinematics in Human Evolution
Laura Tobias Gruss cs 2017 Anat Rec 300:739–751
https://doi.org/10.1002/ar.23550

A broad pelvis is characteristic of most, if not all, pre-modern hominins.
In at least some early apiths (most notably the female Au.afarensis Lucy), it is very broad, and coupled with very short lower limbs.
In 1991, Rak suggested that Lucy's pelvic anatomy improved locomotor efficiency, by increasing stride length through rotation of the wide pelvis in the axial plane.
Compared to lengthening strides by increasing flexion & extension at the hips, this mechanism could avoid potentially costly excessive vertical oscillations of the body's center of mass (COM).

Here, we test this hypothesis.
We examined 3D kinematics of walking at various speeds in 26 adult subjects:
- Do individuals with wider pelves take longer strides? do they use a smaller degree of hip flexion & extension?
- Is pelvic rotation greater in individuals with shorter legs? and those with narrower pelves?

Our results support Rak's hypothesis.
Subjects with wider pelves do take longer strides for a given velocity,
and for a given stride length, they flex & extend their hips less, suggesting a smoother pathway of the COM. Individuals with shorter legs do use more pelvic rotation when walking, but pelvic breadth was not related to pelvic rotation.
These results suggest:
a broad pelvis could benefit any BP hominin (esp. a short-legged apith such as Lucy) by improving locomotor efficiency, particularly when carrying an infant or traveling in a foraging group with individuals of varying sizes. ..

On Saturday, August 21, 2021 at 3:27:36 PM UTC-4, littor...@gmail.com wrote:
> Lucy was no human ancestor, of course:
> most likely, it was a fossil relative of gorillas.
> Google:
> "Australopithecines: Ancestors of the African Apes?"
>
> IOW, we didn't lose it,
> but chimps evolved the "pelvic step".
> > https://phys.org/news/2021-08-humans-ditched-swiveling-hips-shorter.html
> The loss of the ‘pelvic step’ in human evolution
> Human BPism entails rel.short strides vs facultatively BP primates.
> Unique non-sagittal-plane motions ass.x BPism may account for part of this discrepancy.
> Pelvic rotation anteriorly translates the hip, contributing to BP stride length (i.e. the ‘pelvic step’).
> Facultative BPism in non-human primates entails much larger pelvic rotation than in Hs:
> does a larger pelvic step contribute to their rel.longer strides?
> We collected data on the pelvic step in BP chimps & over a wide speed range of human walking.
> At matched dimensionless speeds, Hs have
> - 26.7 % shorter dimensionless strides,
> - a pelvic step 5.4 x smaller than BP chimps.
> Differences in pelvic rotation explain 31.8 % of the difference in dimensionless stride length between the 2 spp.
> We suggest:
> relative stride lengths & the pelvic step have been significantly reduced throughout the course of hominin evolution.
>
> https://doi.org/10.1242/jeb.240440
>
> It would appear that Au.afarensis Lucy still had this pelvic step: a distinctly different kind of BPism at this stage vs Homo:
> https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.23550
>
> Pelvic Breadth and Locomotor Kinematics in Human Evolution
> Laura Tobias Gruss cs 2017 Anat Rec 300:739–751
> https://doi.org/10.1002/ar.23550
>
> A broad pelvis is characteristic of most, if not all, pre-modern hominins..
> In at least some early apiths (most notably the female Au.afarensis Lucy), it is very broad, and coupled with very short lower limbs.
> In 1991, Rak suggested that Lucy's pelvic anatomy improved locomotor efficiency, by increasing stride length through rotation of the wide pelvis in the axial plane.
> Compared to lengthening strides by increasing flexion & extension at the hips, this mechanism could avoid potentially costly excessive vertical oscillations of the body's center of mass (COM).
>
> Here, we test this hypothesis.
> We examined 3D kinematics of walking at various speeds in 26 adult subjects:
> - Do individuals with wider pelves take longer strides? do they use a smaller degree of hip flexion & extension?
> - Is pelvic rotation greater in individuals with shorter legs? and those with narrower pelves?
>
> Our results support Rak's hypothesis.
> Subjects with wider pelves do take longer strides for a given velocity,
> and for a given stride length, they flex & extend their hips less, suggesting a smoother pathway of the COM. Individuals with shorter legs do use more pelvic rotation when walking, but pelvic breadth was not related to pelvic rotation.
> These results suggest:
> a broad pelvis could benefit any BP hominin (esp. a short-legged apith such as Lucy) by improving locomotor efficiency, particularly when carrying an infant or traveling in a foraging group with individuals of varying sizes.. .

Any comparison between H & P w/o hylobatid data background is worthless imo..

On Saturday, August 21, 2021 at 3:41:08 PM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:
> On Saturday, August 21, 2021 at 3:27:36 PM UTC-4, littor...@gmail.com wrote:
> > Lucy was no human ancestor, of course:
> > most likely, it was a fossil relative of gorillas.
> > Google:
> > "Australopithecines: Ancestors of the African Apes?"
> >
> > IOW, we didn't lose it,
> > but chimps evolved the "pelvic step".
> > > https://phys.org/news/2021-08-humans-ditched-swiveling-hips-shorter.html
> > The loss of the ‘pelvic step’ in human evolution
> > Human BPism entails rel.short strides vs facultatively BP primates.
> > Unique non-sagittal-plane motions ass.x BPism may account for part of this discrepancy.
> > Pelvic rotation anteriorly translates the hip, contributing to BP stride length (i.e. the ‘pelvic step’).
> > Facultative BPism in non-human primates entails much larger pelvic rotation than in Hs:
> > does a larger pelvic step contribute to their rel.longer strides?
> > We collected data on the pelvic step in BP chimps & over a wide speed range of human walking.
> > At matched dimensionless speeds, Hs have
> > - 26.7 % shorter dimensionless strides,
> > - a pelvic step 5.4 x smaller than BP chimps.
> > Differences in pelvic rotation explain 31.8 % of the difference in dimensionless stride length between the 2 spp.
> > We suggest:
> > relative stride lengths & the pelvic step have been significantly reduced throughout the course of hominin evolution.
> >
> > https://doi.org/10.1242/jeb.240440
> >
> > It would appear that Au.afarensis Lucy still had this pelvic step: a distinctly different kind of BPism at this stage vs Homo:
> > https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.23550
> >
> > Pelvic Breadth and Locomotor Kinematics in Human Evolution
> > Laura Tobias Gruss cs 2017 Anat Rec 300:739–751
> > https://doi.org/10.1002/ar.23550
> >
> > A broad pelvis is characteristic of most, if not all, pre-modern hominins.
> > In at least some early apiths (most notably the female Au.afarensis Lucy), it is very broad, and coupled with very short lower limbs.
> > In 1991, Rak suggested that Lucy's pelvic anatomy improved locomotor efficiency, by increasing stride length through rotation of the wide pelvis in the axial plane.
> > Compared to lengthening strides by increasing flexion & extension at the hips, this mechanism could avoid potentially costly excessive vertical oscillations of the body's center of mass (COM).
> >
> > Here, we test this hypothesis.
> > We examined 3D kinematics of walking at various speeds in 26 adult subjects:
> > - Do individuals with wider pelves take longer strides? do they use a smaller degree of hip flexion & extension?
> > - Is pelvic rotation greater in individuals with shorter legs? and those with narrower pelves?
> >
> > Our results support Rak's hypothesis.
> > Subjects with wider pelves do take longer strides for a given velocity,
> > and for a given stride length, they flex & extend their hips less, suggesting a smoother pathway of the COM. Individuals with shorter legs do use more pelvic rotation when walking, but pelvic breadth was not related to pelvic rotation.
> > These results suggest:
> > a broad pelvis could benefit any BP hominin (esp. a short-legged apith such as Lucy) by improving locomotor efficiency, particularly when carrying an infant or traveling in a foraging group with individuals of varying sizes. .
> Any comparison between H & P w/o hylobatid data background is worthless imo.

"Brachiating (hylobatids) ... evolved from Miocene aquarborealism" = wading / climbing.

Monkeys evolved in dry forests with fast arboreal quadrupedal pronograde leaping, apes evolved in rainforests with arboreal upright grasping and slow swinging becoming fast brachiation. Wading upright was rare in both and played no important role in terrestrial bipedalism beyond carrying items upright.

On Saturday, August 21, 2021 at 3:24:04 PM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:
> On Saturday, August 21, 2021 at 3:08:45 PM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:
> > On Saturday, August 21, 2021 at 8:26:09 AM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:
> > > On Saturday, August 21, 2021 at 6:12:23 AM UTC-4, Pandora wrote:
> > > > https://phys.org/news/2021-08-humans-ditched-swiveling-hips-shorter..html
> > > >
> > > > The loss of the ‘pelvic step’ in human evolution
> > > >

The HP LCA had a pelvic step of 2/3 hylobatid, 1/3 bonobo.

> > > > ABSTRACT
> > > >
> > > > Human bipedalism entails relatively short strides compared with
> > > > facultatively bipedal primates. Unique non-sagittal-plane motions
> > > > associated with bipedalism may account for part of this discrepancy..
> > > > Pelvic rotation anteriorly translates the hip, contributing to bipedal
> > > > stride length (i.e. the ‘pelvic step’). Facultative bipedalism in
> > > > non-human primates entails much larger pelvic rotation than in humans,
> > > > suggesting that a larger pelvic step may contribute to their
> > > > relatively longer strides. We collected data on the pelvic step in
> > > > bipedal chimpanzees and over a wide speed range of human walking. At
> > > > matched dimensionless speeds, humans have 26.7% shorter dimensionless
> > > > strides, and a pelvic step 5.4 times smaller than bipedal chimpanzees.
> > > > Differences in pelvic rotation explain 31.8% of the difference in
> > > > dimensionless stride length between the two species. We suggest that
> > > > relative stride lengths and the pelvic step have been significantly
> > > > reduced throughout the course of hominin evolution.
> > > >
> > > > https://doi.org/10.1242/jeb.240440
> > > > https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.23550
> > > -
> > > Compared to Homo sapien's & hylobatid's obligate orthograde flat-terrain striding gait, but archaic Homo had intermediate gait ('waddling stride') with the counter-balance (anchor point) being at the rear-skull occipital bone rather than the boney chin in modern Homo sapiens and hylobatids.
> > ---
> >
> > The Hs stride came about later as a result of walking when we returned [??] to a terrestrial existence.

Fallacy. Homo has always been primarily terrestrial, and orthograde since hylobatid LCA.

Another reason to suppose that chimp ancestors were already bipedal is that they went from quadrupedal primates -> orthograde aquarboreal apes --> wading hominids --(Pan/Homo split) --> Pan = knucklewalkers / Homo = swimmer /divers. There's no reason to go from plantigrade quadrupedalism to knuckle-walking unless you go through a transitional upright stage first.

Fallacy, P made home in trees, H made home from trees, both carried more than they waded.

> > F.
> > Hide quoted text
> > On 21/8/2021 2:58 μ.μ., Marc Verhaegen wrote:
> > Humans ditched swivelling hips for shorter stride than chimps
> > Kathryn Knight 2021
> > https://doi.org/10.1242/jeb.243185
> >
> > ... compared with the strides of chimps, even the tallest Hs take rel.short steps:
> > Nathan Thompson (NY Inst.Technol.):
> > "standardized by size, humans really don't have long strides."

Long strides require dense counterbalance for stable gait which is metabolically wasteful because it interferes with other needs. However, Homo carried stones and sticks in swinging arms which produced artificially extended counterbalancing, so the actual stride length was not so significant, and the pelvis rotation was reduced for better efficiency. Fang length, claw length, stride length were all artificially enhanced/replaced in Homo. Lastly, where is the data on hylobatid orthograde walking a treadmill?? They also have small pelvic rotation like Homo, unlike Pan.

> > Until recently, most scientists (yes, unfortunately still most PAs... --mv) believed that the human stride was rel.long for efficiency:
> > "this is taught in almost every introductory class & textbook", although the misconception only became truly apparent when he began delving into the literature.
> > When Thompson began investigating how far chimps rotate their pelvises as they walk, he began wondering:
> > could swivelling their hips hold the key to their longer strides? He decided to compare chimp & human walking over a range of different speeds:
> > does the pelvis rotation provide the chimp's longer stride?
> >
> > "Working with people and animals always has its difficulties." Thompson familiarised the chimps with walking upright on 2 feet while they filmed the animals in 3D.
> > Even working with the human walkers wasn't without its challenges:
> > one volunteer kept getting fits of the giggles because walking in bare feet on the treadmill felt weird:
> > "they couldn't help but walk in a totally bizarre way."
> >
> > Once they reconstructed the human's stride pattern & hip motions in 3D, they the humans down to chimp size:
> > - although Hs legs were proportionally 112 % longer, their strides were 26.7 % shorter,
> > - the chimps swivelled their hips between 28° & 61° (vs Hs ∼8°).
> > When they checked how much further the pelvic rotation got them in terms of stride length, the chimps had a distinct advantage:
> > their swivelling hips extended their stride 5.4 x more (vs their size) than the human's diminutive swivel.
>
> > Thompson:
> > "IMO chimps use pelvic rotations to try to squeeze every bit of stride length out, otherwise their strides would be – absolutely – very small":
> > apes & monkeys tend to walk on crouched legs, that naturally shorten their stride:
> > "I don't think there are a lot of options other than rotating the pelvis, given their anatomical constraints."
> >
> > But why have humans ditched swivelling their hips when it could extend their strides further?
> > Thompson suggests:
> > extreme rotations of the hips could throw out the natural swing of our arms & legs (which counterbalance each other) forcing our muscles to work harder, making walking less efficient: a price that simply might not be worth paying for an increased stride length:
> > scientists had thought for decades that Hs had evolved the longest possible stride for efficiency,
> > but now it turns out: our stride is considerably shorter <chimps:
> > other factors have had a larger impact on the way we walk:
> > "Hs have had c 7 Ma of selective pressure for economical BPism:
> > there has been a lot of time to experiment with the costs & benefits,
> > so it might be worth it to walk with slightly shorter strides, because whatever energy we lose, we might make up elsewhere."
> >
> >
> > (obviously, the experiment is excellent, but the interpretation is the traditional anthropocentrism,
> > the solution is not so difficult IMO:
> > - chimps evolved from aquarboreals to knuckle-walkers,
> > - we evolved to shallow-divers & then waders --mv) aat.io
> > ---
> Knuckle-walking could just as well be from descending from earlier brachiating apes, whose forelimbs had adapted to grab and hang from branches, like gibbons still do.

Gibbons don't knucklewalk or wade.

Making such a transition from the canopy to the forest floor could then solicit adapting those grabbing forelimbs to walk on your knuckles instead.

Fallacy. Knucklewalking = swamp/river forest & wetplains moving quickly between on savannas.
>
> https://www.natureplprints.com/p/729/northern-white-cheeked-gibbon-nomascus-19713898.jpg
> https://upload.wikimedia.org/wikipedia/commons/thumb/a/a7/Western_Lowland_Gorilla.jpg/1200px-Western_Lowland_Gorilla.jpg
> ce aat.io
> -
>
> > If I have time, I will review these claims for errors or fantasies.
>
> -
>
> on Elaine: And then there came three men, Ernst Mayr, George Gaylord Simpson, and Theodosius Dobzhansky. And they got together and they wrote a book called The New Synthesis. And they said: "There is no point in arguing who's right, Darwin or Mendel. They were both right and with a bit of trouble we can get them fused into a new synthesis." And by next year, in the course of next year, we should be able to do the same thing, get a new synthesis which fuses Darwin and Mendel and Hardy.

NONE OF THEM MENTIONED WHERE HOMO WAS FOR 1/3 OF THEIR LIVES ASLEEP. WHY?

And then we will explain why we are so different.

Elaine claimed they slept in sea caves, sea lions who do that are thickly furred!

As it is now, when the creationists say: "Well, if man was not a special creation, why is he so different from the others?" We've got to say: "I don't know."

Pandora wrote:
> https://phys.org/news/2021-08-humans-ditched-swiveling-hips-shorter.html
>
> The loss of the ‘pelvic step’ in human evolution
>
> ABSTRACT
>
> Human bipedalism entails relatively short strides compared with
> facultatively bipedal primates. Unique non-sagittal-plane motions
> associated with bipedalism may account for part of this discrepancy.
> Pelvic rotation anteriorly translates the hip, contributing to bipedal
> stride length (i.e. the ‘pelvic step’). Facultative bipedalism in
> non-human primates entails much larger pelvic rotation than in humans,
> suggesting that a larger pelvic step may contribute to their
> relatively longer strides. We collected data on the pelvic step in
> bipedal chimpanzees and over a wide speed range of human walking. At
> matched dimensionless speeds, humans have 26.7% shorter dimensionless
> strides, and a pelvic step 5.4 times smaller than bipedal chimpanzees.
> Differences in pelvic rotation explain 31.8% of the difference in
> dimensionless stride length between the two species. We suggest that
> relative stride lengths and the pelvic step have been significantly
> reduced throughout the course of hominin evolution.
>
> https://doi.org/10.1242/jeb.240440
>
> It would appear that Australopithecus afarensis ("Lucy") still had
> this pelivic step, indicating a distinctly different kind of
> bipedalism at this stage compared to Homo:
>
> https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.23550
>

This would seem to tie in:

https://www.nature.com/articles/s41586-020-2053-y
Stiffness of the human foot and evolution of the transverse arch

Abstract
The stiff human foot enables an efficient push-off when walking or
running, and
was critical for the evolution of bipedalism. The uniquely arched
morphology of
the human midfoot is thought to stiffen it, whereas other primates have
flat feet
that bend severely in the midfoot. However, the relationship between midfoot
geometry and stiffness remains debated in foot biomechanics, podiatry and
palaeontology. These debates centre on the medial longitudinal arch and have
not considered whether stiffness is affected by the second, transverse
tarsal arch
of the human foot. Here we show that the transverse tarsal arch, acting
through
the inter-metatarsal tissues, is responsible for more than 40% of the
longitudinal
stiffness of the foot. The underlying principle resembles a floppy
currency note
that stiffens considerably when it curls transversally. We derive a
dimensionless
curvature parameter that governs the stiffness contribution of the
transverse tarsal
arch, demonstrate its predictive power using mechanical models of the foot
and
find its skeletal correlate in hominin feet. In the foot, the material
properties of the inter-metatarsal tissues and the mobility of the
metatarsals may additionally influence the longitudinal stiffness of the
foot and thus the curvature–stiffness relationship of the transverse
tarsal arch. By analysing fossils, we track the evolution of the curvature
parameter among extinct hominins and show that a human-like transverse arch
was a key step in the evolution of human bipedalism that predates the
genus Homo
by at least 1.5 million years. This renewed understanding of the foot may
improve
the clinical treatment of flatfoot disorders, the design of robotic feet
and the study
of foot function in locomotion.