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Chimpanzee Feet Allow Scientists a New Grasp on Human Foot Evolution

Discussion in 'General Issues and Discussion Forum' started by NewsBot, Feb 14, 2017.

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  1. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
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    News Release:
    Chimpanzee Feet Allow Scientists a New Grasp on Human Foot Evolution
    FEBRUARY 8, 2017
     
  2. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
    1
    Chimpanzee and human midfoot motion during bipedal walking and the evolution of the longitudinal arch of the foot.
    Nicholas B. Holowka, Matthew C. O'Neill, Nathan E. Thompson, Brigitte Demes.
    Journal of Human Evolution, 2017; 104: 23
     
  3. Rob Kidd

    Rob Kidd Well-Known Member

    MMMmmmm. Apples and oranges, me thinks. What seems to be being reported is that (while they do not use the term), a substantial midtarsal break occurs in chimpanzee feet during midstance - that does not occur in normal human feet. That is, to a first approximation the midtarsal oblique axis undergoes a substantial "pronation" in chimpanzees. The human foot is noted to undergo a greater range of motion - but in the other direction - ie midtarsal oblique axis supination - presumably as a result of the windlass effect. While I suspect an actual quantification & comparison of the amount of movement has not been undertaken before, they are not the same thing. Unless of course, that I have missed the point. Huge amounts of this sort of work came out of Rob Crompton's lab in Liverpool during the first decade of this century.
     
  4. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
    1
    Chimpanzee ankle and foot joint kinematics: Arboreal versus terrestrial locomotion.
    Holowka NB et al
    Am J Phys Anthropol. 2017 Jun 8. doi: 10.1002/ajpa.23262.
     
  5. scotfoot

    scotfoot Active Member

    So why would a non divergent first ray and the development of a medial longitudinal arch be of benefit to an obligate biped ?

    Perhaps one of a number of reasons might be because pronation of the foot would allow a more liner progression of the COM during gait with less lateral movement since a pronating foot allows the weight bearing tibial head to move towards the medial sagittal plane .

    Any thoughts ?
     
  6. Rob Kidd

    Rob Kidd Well-Known Member

    There no simple answer to your question above, Scotfoot, but there are some guiding principles, such as reducing bending stresses and the evolution of the windlass. I have attached some light reading for you; when you haave digested, we may continue this discussion. Please bear in mind that these were written approaching 20 years ago, Rob
     

    Attached Files:

  7. scotfoot

    scotfoot Active Member

    Hi Rob ,
    I read the papers you referenced ,above ,and in the process of comparing the Chimpanzee rearfoot to that of a human I think I have an idea of one of the ways in which the intrinsic foot muscles contribute to balance .
    The question I asked myself was what type of balance system can take the apparently difficult to balance , tall ,top heavy ,human phenotype and use this shape to advantage ?

    Well , first consider balancing a pencil on your finger . Its very difficult .
    Easier to balance is a long broom handle due to inertia . Easier still is the act of balancing a complete broom on your finger /palm with the broom head in the air and the end of the broom on your hand .
    So can the head of the tibia balance in this way on the talus/calcaneal unit ? I think the answer may be yes , at least for postural stability in the medio lateral direction .

    Previously , Luke Kelly (1) has shown that the intrinsic foot muscles can control foot posture including the condition of the medial longitudinal arch and ,in my opinion ,this could lead to inversion and eversion of the calcaneus, and then via the talus ,to a movement of the tibal head relative to the COG .

    Another paper has shown that the vestibular apparatus has a direct link to some of the intrinsic foot muscles showing the have a key role in balance . (2)

    A third paper (3) indicates that in the absence of strong intrinsics the extrinsics seem take on more of role in postural stability an so enlarge .

    So what I am saying overall is that the intrinsics handle small medio lateral perturbations via calcaneal positioning and with larger perturbations the extrinsics kick in to assist .

    This theory places the intrinsics right at the heart of human balance .

    What do you think ?





    Paper 1 Recruitment of the plantar intrinsic foot muscles with increasing ...

    https://www.researchgate.net/.../51593348_Recruitment_of_the_plantar_intrinsic_foot...22 Dec 2017 - Full-text (PDF) | The aim of this study was to determine the difference in activation patterns of the plantar intrinsic foot muscles during two quiet standing tasks with increasing postural difficulty. We hypothesised that activation of these muscles would increase with increasing postural demand...






    Paper 2
    vestibular modulation of the abductor hallucis and the ... - Scholars' Bank

    https://scholarsbank.uoregon.edu/xmlui/bitstream/.../Final Thesis-Wallace.pdf?...1
    by J Wallace - ‎2016 - ‎Related articles
    explore the vestibular system. The purpose of this experiment was to determine if intrinsic foot muscles are modulated by vestibular activity and to elucidate any changes in the association between the vestibular stimulation and electromyography (EMG) responses in response to changes in head position, visual cues, and ...

    Paper 3
    Foot muscle morphology is related to center of pressure sway and ...

    https://www.ncbi.nlm.nih.gov/pubmed/28575753
    by X Zhang - ‎2017 - ‎Related articles
    Gait Posture. 2017 Sep;57:52-56. doi: 10.1016/j.gaitpost.2017.05.027. Epub 2017 May 25. Foot muscle morphology is related to center of pressure sway and control mechanisms during single-leg standing. Zhang X(1), Schütte KH(2), Vanwanseele B(3). Author information: (1)Human Movement Biomechanics Research ...
     
  8. scotfoot

    scotfoot Active Member

    With regard to the above it would appear that babies can hold their bodies in an upright position long before they can balance on their feet . Included below is a link to a video of a man balancing babies on the palm of his hand with the babies holding themselves straight whilst the man moves his hand to keep them balanced . A bit like the head of the tibia balancing on the taloncalcaneal complex with the intrinsics keeping things in balance .

    Note -in the video the authors point out that the activities shown in the video should not be tried at home !

    Video
    Icelandic swim instructor teaches babies to stand on their own ...

    upload_2018-1-13_11-14-37.jpeg ▶ 1:45

    20 Jul 2017 - Uploaded by Business Insider UK
    Snorri Magnusson is Iceland's "Baby Whisperer." The swimming instructor teaches babies as young ...
     
  9. scotfoot

    scotfoot Active Member

    Look at figure 6 in the paper below . Again, Luke Kelly .

    Intrinsic foot muscles have the capacity to control deformation of the ...

    rsif.royalsocietypublishing.org/content/11/93/20131188
    by LA Kelly - ‎2014 - ‎Cited by 50 - ‎Related articles
    29 Jan 2014 - We test the hypotheses that activation of the three largest plantar intrinsic foot muscles, abductor hallucis, flexor digitorum and quadratus plantae is associated with muscle stretch in response to external load on the foot and that activation of these muscles (via electrical stimulation) will generate sufficient ...
     
  10. scotfoot

    scotfoot Active Member

    Further to the above , an extremely interesting paper was very recently published , Koyama et al 2017 (below) , which looked at fatiguing the muscles of the foot and the effect this has on postural sway . They found that the exercises reduced some aspects of postural sway .
    The authors stated -

    "This study revealed that fatiguing foot muscle exercises decreased foot muscle strength and altered postural sway during standing. Interestingly, the fatiguing foot muscle exercises decreased the COP range and velocity while standing compared with the pre-fatigue conditions. The decreased foot muscle strength after the exercises was not associated with changed postural sway during standing after the exercises ".

    What makes this paper so interesting is that the exercises used in the study would have fatigued the extrinsic foot muscles but not the intrinsics ( calf raises and toe curls do not target the intrinsics and a toe grip dynamometer measures extrinsic toe flexor strength )

    Contrary to the interpretation of the authors I believe this paper may show better postural stability with less extrinsic foot muscle input and greater reliance on the intrinsics .

    Paper
    Altered postural sway following fatiguing foot muscle exercises - PLOS

    journals.plos.org/plosone/article?id=10.1371/journal.pone.0189184
    by K Koyama - ‎2017
    7 Dec 2017 - The activities of the intrinsic and extrinsic plantar muscles contribute to postural stability during upright standing, especially in the single-leg standing [9]. Foot muscle strength is considered to be one of the important essentials that provides postural control while standing [10]; however, the relationship between foot muscle ...
     
  11. Rob Kidd

    Rob Kidd Well-Known Member

    Frankly Scottfoot, I would not get toooooo bogged down in the individual function of the intrinsic muscles. I am a fair age now - nearly 63, but what I have learned in my rather extended life is that much early work was very good,in spite of empirical equipment. A classic example is Vern Inmans work - most of his stuff he made himself, at least, so I am told. You should read the 1964 paper of Mann and Inman - phasic muscle actions of the intrinsic foot muscles. It is now 30 years since I read it but my memory says that the summary was that collectively (not individually) they work harder and longer in flat foot. The truth of the matter to me - stand by to be slammed, Kidd, is that the intrinsic muscles have little apart from a collective arch supportive function. That is, to assign a specific contractile function to a foot intrinsic muscles in Homo sapiens is simplistic at best. So: back to the arch - and you made comment earlier about why lose the divergent first ray and opposing first toe.

    1) the posterior component. Raising of the subtalar axis to ~45' (forgive me 42=~45; 45=1/2 of 90), gives us a torque conversion that is vital for the bipedal habit. The act of raising the axis also raised the anterior aspect of the calcaneus, and Bingo, we have the posterior portion of the arch. Now, the windlass is critical in efficient bipedal ambulation. For that one needs all toes in direct alignment with their metatarsals. This couples with a (relatively) huge torsion of the talar head gives you the anterior portion of the arch. Let us not dwell on talar head torsion now - 'cept to say that it aids in M/T jt ROM reduction. This is critical to the propulsive phase of gait, coupled with windlass.

    Of course this is simplistic - there are bipedal mods all over the foot - but there are the critical ones, at least in my opinion.

    Many mistakes were made in the interpretation of the fossil record. In our publication of the OH8 foot in 1996, we mistakenly suggested that the first ray was still divergent with a well developed calcaneus (IE Mortons hypothetic prehuman foot)- at this stage the medial cuneiform had yet to be subjected to multivariate study; A later paper on little foot (StW573) examined both its medial cuneiform and that of OH8 - and both clearly had a non-divergent first ray. It is now clear that the loss of a divergent first ray is an early adaptation, hindfoot changes taking place later (Australopitheis sediba, Science, Bernie Zipfel, ex-pod, was first author, I was third, I think). This is of course a HOX gene issue - that deals with disto-proximal changes.

    At some point - variable I am sure, the calcaneo-cuboid joint became very stable with a huge decrease in its ROM, essentially due to a pronounce process calcaneus- this had certainly occurred in OH8 by its suggested date of 1.8MA. However it had not in the sediba foot, which dates a little earlier at 1.9MA - Mosaisim is the norm - OH8 was East African, sediba was South African - one must expect mosaic evolution. This of course is caudo-cranial, and is down to sonic hedgehog genes

    What has yet to be unearthed from the fossil record is something that demonstrates the third and final body plane/genetic control - that of the Wnt systems (and their upstream and downstream qualifiers); these control dorso ventral changes. Before you jump on me, I know that these are particularly poorly understood.

    A sad, or is it an exciting part of palaeoanthropology, is that frequently it throws up more questions than answers. Thus one has to be incredibly careful in the manner in which to phrase your opinions. And the first rule of science is this: if you are wrong, for Gods sake be the first to say so! If one reads the Little foot paper, one will find a huge mea-culpa with regards to the first ray status. I have attached the relevant papers in case to need some light reading to send you to sleep.

    With regard to the sediba paper in Science, my contribution was largely the big number crunches which produced the canonical variates analysis of the talus and calcaneus - and thus their bivariate plots. To show you how little is needed sometimes to do quality science, this was all done while living in a motorhome in the Northern Territory with no mains power.

    Not sure if this helps - but it has ruled my life for thirty years.

    Rob
     

    Attached Files:

  12. scotfoot

    scotfoot Active Member

    Rob
    At present Dr Karen Mickle and colleagues are working on a paper entitled "Evaluating a foot strengthening exercise program to improve foot function in adults with diabetes " . Knowing what little I know about getting a research project up and running , I can only wonder at the tenacity required to get this one past the powers and that be .
    But I will say this . If Mickle can show a significant improvement in the intrinsics of the exercise group then the wide ranging functions of these muscles will be more evident .
    If this trial is successful then eventually we might see improvements in patients balance ,gait ,the lymphatic system of the foot ,venous drainage ,blood flow into the foot , a reduction in foot ulcers ,less infection ,and reduced levels of foot pain through more normal plantar pressure distribution .
    Can't wait !
    With regard to my/the theory that I put before you , it may not be correct . However I feel it fits the known facts , and ,on balance ,I think it might well have merit .

    Regards
    Gerry
     
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