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The evolution of bipedalism

Discussion in 'Podiatry Trivia' started by scotfoot, Oct 27, 2017.

  1. CEngelbrecht

    CEngelbrecht Active Member

    It has never been an issue.

    https://en.wikipedia.org/wiki/Gathering_seafood_by_hand

    We don't exactly look like gibbons today, do we? Some pressure must have been going on to shape us the way we are.
    [​IMG]
    [​IMG]
    Just add water, it all adds up, like nothing else can. It's not rocket science.

    I'm sorry, did you just say, that the human foot is more flexible than the chimpanzee one? Seriously?
    [​IMG] [​IMG]
    It's getting more and more Magic Bullet Theory in here. Why is it such a problem, if our unique features amongst the apes are related to water? So what, if we're an old beach ape?

    Yes, we descend from brachiating apes as old as 35mya, and as young as ~10mya. That's the gibbon like stage in our evolution you're talking about. That's the mutual origin of all simians. And that is likely a big part of why all simian species become predictably bipedal in shallow water, and thus why it became habitual in human beings. As an exaptation to their forelimbs originally being adapted to dynamic interaction with the surroundings and not constant contact with the ground.
    [​IMG]
    [​IMG]
     
  2. scotfoot

    scotfoot Well-Known Member

    Last edited: Nov 11, 2017
  3. CEngelbrecht

    CEngelbrecht Active Member

    They're rubbish for climbing, that's for sure. What exactly is your point, that our foot is closer to the gibbons' than to the chimp's?

    [​IMG]
    [​IMG]

    For whatever reason and in whatever substrate, human habitual bipedalism on a vertical spine shaped the human foot towards its unique form amongst the apes. And if you don't add water and selection for increased hydrodynamics, you have no selective reason for hominins to evolve that. Climbing doesn't explain it, 'cause then we would see the same principle in e.g. gibbons. Moving about on open grasslands doesn't explain it, 'cause then we would see it in e.g. baboons. There's no convergent evolution to find for these unique traits... unless you add water. Why is this such a problem?

    Other mammal taxa have semiaquatic ancestry. Elephants, rhinos, tapirs, suids, shrews. No problem what so ever for anthropologists. Why all this hysteria because an ape likely went in and out of the water over the eons as well? Is it only because it's ourselves and we always love to delude ourselves into thinking, that we can make up our own rules in the tree of life?

     
  4. scotfoot

    scotfoot Well-Known Member

    Imagine the following hypothetical situation .
    First imagine a small lake about the size of a football pitch and about 10 feet deep in the middle . Now put a boat in the center of the lake and place a man ,with no experience of swimming in water, in said boat . Now add in an adult of each of the following species and all of which have no experience of swimming . Hedgehog ,cat , dog , mouse ,sheep ,pig ,emu, badger,squirrel, goat,horse,hamster,and an aardvark .
    Now let's say the boat sinks and all these animals are tipped into the water alongside our man . What happens ?
    All the animals can swim instinctively and make it to shore. And the man drowns .

    Aquatic ape theory !
     
  5. Rob Kidd

    Rob Kidd Well-Known Member

    In partial reply and comment to the feet above, Christian and others please note the attached plot. This is a canonical variates plot of variates (AKA Axes) one against two of a series of function dimensions that have been indexed to emphasise functionally important features. In doing so it does de-emphasise raw size (that is another ball park, let's not go there to play today!).

    Ignore "8". Now look at the positions of the African apes, H. Sapiens and Pongo. They occupy corners of a triangle that could be interpreted as representing the three known locomotor patterns in extant apes: bipedalism, Knuckle-walking, and some variety of arborealism.

    However: beware the false trichotomy; do not assume that these are the only possible locomotor behaviours.

    8 is the talus of OH8 - Olduvai hominid 8 from the Olduvai gorge. The closer it fits to another species the more similar in form and therefore function it is to that species. OH8 clearly had an arboreal aspect to its lifestyle. While there is no evidence what-so-ever (whatever you have been told) that OH8 is a direct ancestor of ours (ancestor yes, direct, who knows?) this tells us that an ancestor of H. sapiens does have an arboreal aspect to its locomotion.

    Thus, it is not surprising that one is picking up gibbon-like functional affinities. However please note the HUGE difference in overall proportions.

    There no evidence at all for a knuckle walking intermediary between an arboreal and bipedal-type locomotion. The question really is whether the early bipedal locomotion was equatic or terrestrial.............

    Rob
     

    Attached Files:

  6. CEngelbrecht

    CEngelbrecht Active Member

    Uhuh.

    Crash survivors swam for six hours | The Independent
     
  7. scotfoot

    scotfoot Well-Known Member

    Rob ,the foot of an extant gibbon is indeed very different from the Homo Sapien foot which is closer to that of other extant apes such as the chimpanzee .
    It is also true that there is no proof that the last common ancestor (LCA) of Homo and Pan was close to Pan in phenotype although some think this to be the case .
    What strikes me as possible is that the last common ancestor was similar to Pan and this animal gave rise to a gibbon like animal which ,through brachiation , developed a pelvis better adapted to walking bipedally than the original LCA .
    Loss of habitat may have later forced this animal to the ground where ,through atavism , if may quickly have reacquired a more pan like foot but which may have retained some gibbon like qualities .

    Gerry
     
  8. CEngelbrecht

    CEngelbrecht Active Member

    One big problem with that suggested scenario: Homo would then have no selective reason for losing the thumb-like big toe still present on all other apes and instead evolve one, that is parallel to the other toes. Then the conditions would've been exactly the same for both Homo and Pan.

    [​IMG] [​IMG] [​IMG]
    Any particular reason why the human big toe couldn't possibly have been selected for increased hydrodynamics? Then and only then it all adds up.

     
    Last edited: Nov 13, 2017
  9. scotfoot

    scotfoot Well-Known Member

    Christian , in thread 37 you wrote -

    " If the human foot should have evolved completely dry e.g. for bipedal running, it's then peculiar, that the foot didn't keep the outward big toe as in all other apes, since that would otherwise create better "tri-pod" stability for each running step. "

    Does anyone else think the same way about this "tri-pod" as you do ? Anyone at all ?
     
  10. CEngelbrecht

    CEngelbrecht Active Member

    We don't have the outward big toe, as the only hominoid. Latest fossil hominoid to have it is Ardipithecus. Why would losing it be an energy benefit for bipedal running?

    Exactly, it isn't. Conversely, it would be an energy benefit for gliding through water through less drag.
     
    Last edited: Nov 13, 2017
  11. Rob Kidd

    Rob Kidd Well-Known Member

    Gerry, in reply #47 you said:

    Rob ,the foot of an extant gibbon is indeed very different from the Homo Sapien foot which is closer to that of other extant apes such as the chimpanzee .
    It is also true that there is no proof that the last common ancestor (LCA) of Homo and Pan was close to Pan in phenotype although some think this to be the case .
    What strikes me as possible is that the last common ancestor was similar to Pan and this animal gave rise to a gibbon like animal which ,through brachiation , developed a pelvis better adapted to walking bipedally than the original LCA .
    Loss of habitat may have later forced this animal to the ground where ,through atavism , if may quickly have reacquired a more pan like foot but which may have retained some gibbon like qualities .


    Those (pitifully sparce) remains that we have of prehuman fossil foot bones would not agree with this. All the available evidence (which is three parts of bugger all), suggests that the first ray had become non-divergent before leaving the tree. While at the same time, the hindfoot was still of an arboreal type. This is typified by Australopithecus sediba, which to my knowledge, has the one complete calcaneus of the era.

    You use the term "atavism" in an odd manner - an evolutionary throw back. You seem to be suggesting that Homo, upon landing on the ground acquired a chimp-like foot, including its first ray.

    Christian, in your thread #37 post, the comments re: Big toe:

    If the human foot should have evolved completely dry e.g. for bipedal running, it's then peculiar, that the foot didn't keep the outward big toe as in all other apes, since that would otherwise create better "tri-pod" stability for each running step.

    I find this totally at odds with what we know about a) human evolution, and 2) the biomechanics of bipedal gait. While I am no expert in biomechanics, I would suggest that the presence of a divergent first ray would be a disaster for the development of an efficient bipedal locomotion. Start off with the windlass and the support of the arch during (in particular), the propulsive phase of gait.

    Rob



     
  12. scotfoot

    scotfoot Well-Known Member

    I am really just trying to explore ways in which a viable biped could come about . If an species starts out with a certain phenotype and then this alters due to a new phenotype due to environmental factors , then can some of the original characteristics randomly re-emerge and be selected for , if the environment reverts back to the original state .( Over many thousands of years )
     
  13. CEngelbrecht

    CEngelbrecht Active Member

    By doing this for a couple of hundred thousand years.
    [​IMG] [​IMG]

    Even if the above should somehow not illustrate the origin of human bipedalism, you can't say it's not a reasonable thought. Considering that ... every ... single ... ape and monkey species on planet Earth becomes vertically bipedal in shallow water.

    Like the elephant group, you mean? All elephants, living or extinct, descend from semiaquatic creatures ~35mya. While some elephantidea species migrated to arctic regions and reevolved fur, their ancestors had previously lost in the water, as mammoths and mastodonts. Humans are not the only mammal taxa to wade into the water and leave it again, 'cause water bodies come and go across the geological calendar. Often you'd have to adapt to drier conditions or die out, though you keep traits evolved from the eras of being in the water.



    It's not at all controversial or insane to talk about swimming elephants in paleontology. Why is it such rot to talk about swimming apes in paleoanthropology, when you have all the scars of evolution on the body of those apes to show for it?

    [​IMG]

    It's only because it's ourselves, isn't it? We can't study ourselves without breaking out the pitchforks. Here we have answers to a host of questions left over from Darwin and Wallace about how we came to be, and all we do is trying to burn the discoverer.
     
  14. scotfoot

    scotfoot Well-Known Member

    "Christian, in your thread #37 post, the comments re: Big toe:

    If the human foot should have evolved completely dry e.g. for bipedal running, it's then peculiar, that the foot didn't keep the outward big toe as in all other apes, since that would otherwise create better "tri-pod" stability for each running step.

    I find this totally at odds with what we know about a) human evolution, and 2) the biomechanics of bipedal gait. While I am no expert in biomechanics, I would suggest that the presence of a divergent first ray would be a disaster for the development of an efficient bipedal locomotion. Start off with the windlass and the support of the arch during (in particular), the propulsive phase of gait.

    Rob"

    Any chance you could respond directly to this rebuttal of your tri-pod theory ?
     
  15. CEngelbrecht

    CEngelbrecht Active Member

    Why haven't we seen an inkling of this in e.g. grassland baboons? No bipedalism, no inward big-toe.

    [​IMG]

    The savannah hypothesis has been dead for decades, it cannot be supported by the standing evidence. So somehow, our ancestors evolved vertical bipedalism remaining in a woodland scenario, the same scenario chimps and gorillas evolved knuckle-walking in.

    [​IMG]

    If we don't add the bloody water, which is already supported by all (all) simians being bipedal in water (AND loss of fur, AND the big brain, AND the chubby infants, AND the hooded nose, AND exceptional diving ability, AND ...), then we have no selective reason what so ever for Homo to evolve in a completely different direction than Pan and Gorilla. Considering convergent evolution, then we would've been knuckle-walkers too. Which we ain't. There's only water left to explain it.
     
  16. scotfoot

    scotfoot Well-Known Member

    And so ,to conclude my involvement in this thread , the gibbon like hominin I have been speaking about might quickly have achieved larger size (over generations of course ) once freed from the constraints of brachiation in the forest canopy, and gone on to evolve into me ,Christian and other stick wielding homosapiens .Most of whom can't swim at all !

    Cheers

    Gerry
     
  17. CEngelbrecht

    CEngelbrecht Active Member

    Which is why gorillas are the largest extant hominoid, I gather? Only eclipsed by extinct Indian gigantopithecus, ancestor to extant orangutans.

    [​IMG]

    Why is it such a problem with water having affected our unique evolution? Don't you take regular showers?
     
  18. SingaPod

    SingaPod Member

    Isn't it more likely that the development of bipedalism is multi-factorial.

    For example tool use, our simian relatives utilize tools for various purposes, however due to their method of locomotion it is difficult for them to transport tools so they tend to use simple tools that can be whipped up rapidly. Once you are bipedal even to a limited extent you gain the ability to carry things with you. This allows you to modify tools to improve them which in turn allows you to increase your efficiency in whatever task the tool is used for, this in turn makes you better at the task which increases your chances of survival. This results in a cyclical pressure on both bipedalism and tool use/improvement, as tool use aids survival so is selected for but as bipedalism allows for you to have free hands to carry and use those tools that would also be selected for at the same time.

    The aquatic or rather semi-aquatic ape theory (which to my knowledge is generally related to living alongside sea coasts) has the advantage that it fills some of the problems of the older savannah ape theory. One of these problems is that the resources needed to build the large complex brain that hominids developed are rare in a savannah environment while being abundant along the coastline. As seafood often requires more sophisticated methods to gather this may also have been a spur to tool use which as outlined above could have also spurred bipedalism. The advantages of bipedalism are evident in a situation where wading in the water to gather food.

    One other factor to consider is a hunting method used by many hunter-gathering societies, and no doubt used by earlier varieties of hominid as well, which is exhaustion hunting. This is where animals are either kept from water until they collapse from dehydration or where they are caused to run until such a point that they overheat/collapse from exhaustion. Humans are remarkably good at heat management, hairlessness helps with this, if improved locomotion allows our ancestors to take advantage of this fact then it would be a major driving force in improving bipedal locomotion.

    Remember it doesn't have to be the same thing all the way through driving this process. Certain elements of bipedalism may also not at the time been advantageous they may have just not been so deleterious that they would prevent genes being passed on.
     
  19. scotfoot

    scotfoot Well-Known Member

    Hi Rob ,
    With regard to the" killer ape theory " ,which I have no strong views about , I recently came across this BBC news report . The report centers around a well researched piece of work concerning lethal violence among chimpanzees . Its a real eye opener .

    Gerry

    Murder 'comes naturally' to chimpanzees - BBC News

    www.bbc.co.uk/news/science-environment-2923727618 Sep 2014 - A major international study finds that killings among chimpanzees result from normal competition, not human interference.
     
  20. CEngelbrecht

    CEngelbrecht Active Member

    Recommend this:
    https://en.wikipedia.org/wiki/Demonic_Males
     
  21. Rob Kidd

    Rob Kidd Well-Known Member

    It is 6.30am and I am in a caravan park about halfway down the Eyre Peninsular in South Australia - a perfect place to be able to bore you with my thoughts!
    Chimpanzees have long been known to be revoltingly violent creatures. I should clarify that; Pan troglodytes has, Pan Paniscus has not. The latter seem to solve all their problems with sex - they have more ways of doing it that we can even dream about. A comical piece of evolution - all that separates the two species is the Zaire river, on the edge of what was once the Belgium Congo. Hominoids all together have traits not to be proud of: rape is well recognised in Orangs.

    Now here is a thought for you (we are all over 18?) Among other things, I study patterns of sexual dimorphism, which once you leave the pelvis et al, seemingly has nothing to do with sex. When you cut to the chase, sexual dimorphism (isms?) present in three manners: size, shape and variation. To use, by manner of example, a group of chimpanzees, typically there will be one male, and perhaps 25 female sets of genes flowing into the gene pool. This explains to us nicely why the above patterns occur. Males will be bigger as they have to beat the crap out of the competition, thus big boy genes flow forward. It also explains the variation, as there female gene pool is so much wider. Let us leave shape to another time, but you will find it everywhere you look. So if this explains (by manner of example, why female chimpanzees are more variable (and it does), why is it true in humans? Yes, it is, not as pronounced, but it is there, plain, for all to see.

    I can offer you two explanations. 1) pair bonding is lip service only, and there is a lot of naughties taking place behind closed doors. 2) We are playing evolutionary catchup, and out patterns of morphological variation today, are reflective of sexual habits of perhaps 20,000 years ago.

    I read recently that contrary to popular belief, life-long pair bonding in many species of birds was fiction - one in five males in some species are bringing up young they erroneously believe to be theirs.

    Any thoughts? Let us get the plank out of our own eyes, before the spec of dust in Pan's!
     
  22. CEngelbrecht

    CEngelbrecht Active Member

    No different from Homo sapiens, then.

    [​IMG]
     
  23. Rob Kidd

    Rob Kidd Well-Known Member

    Christ! Are you looking to spend Christmas in the tower of London, awaiting your beheading?!

    Actually I read very many years ago that at the insistence of a senior Royal, Harry was DNA'd and found to be pucka.
     
  24. CEngelbrecht

    CEngelbrecht Active Member

    If Jimmy Carr can, so can I.

    Would they ever have declared otherwise?

    Anyway, that's another family tragedy, no reason to amuse yourself more than necessary.
     
  25. tefling

    tefling Welcome New Poster

    Excellent discussion!

    According to the YT documentary "Timeline - Discovery of the Earliest Human Ancestor", Orrorins 6Mya (plausibly) lived like Orangutans, spending much time standing and walking upright on branches high in the canopy. Sahelanthropus (Chad) and Orrorin (Kenya) lived 6Mya on the periphery of the central African humid rainforest biome harboring chimpanzee ancestors. The proto-homonins also had human-like back molars for chewing tough nuts & seeds, berries & insects, indicating an omnivorous diet.

    Someone knowledgeable about Miocene African rainforest vs. tropical savannah biomes could (plausibly) infer what trees the proto-homonins inhabited and what seeds, nuts & berries they were consuming. The "Gibbon hypothesis" discussed in this thread could also (plausibly) be called an "Orang hypothesis" and seems to reflect a speciation from proto-chimpanzees arising from a humid rainforest vs. tropical savannah biome split, somehow favoring an Orangutan-like lifestyle chewing on tough seeds, nuts & berries high up in the canopy, from (often) upright postures on branches -- long enough for bipedalism and human (molar) like dentition to evolve in an arboreal environment.

    Also offer that the Nile river, which first formed about 6Mya, may have created a barrier separating surviving proto-hominins from proto-chimpanzees. Cp. the boundaries between chimps & bonobos correspond (IIRC) to rivers.
     
  26. scotfoot

    scotfoot Well-Known Member

    Why evolve into terrestrial bipeds, what big advantages does it bring?

    In a nutshell it allows the generation of large amounts of kinetic energy in hand held objects, and that more than anything else is what separated our early ancestors from the proto- chimp species.

    Our long limbed, gracile type ancestors always needed to develop away from proto- chimps and so isolation would have been required for example, and most probably, rivers were involved.

    So we have proto-humans walking upright high in the forest canopy ( see clip below ) . They become terrestrial ,find they can take down huge amounts of prey throwing sticks at high velocity and we are well on our way.

    Mentioned earlier in this thread is Dr Algis Kuliukas PhD (University of Western Australia) . I spoke to Dr Kuliukas via twitter some time ago and he was convinced that gibbons don't walk around in the forest canopy; till I showed him this clip.
     
  27. tefling

    tefling Welcome New Poster

    Given Sahalanthropus in Chad, proto-hominins 6Mya seem associated with the "Savannah - Woodlands" biome surrounding the central African tropical humid rainforest, where chimps still survive to this day.

    But there are no surviving "tree canopy chimps" in such environments today.

    Perhaps, as the forests "thinned out from under their feet", and the "tree canopy chimps" were forced out into the Savannah and down onto the ground, none of such groups were able to survive predation and/or competition... except one group, in eastern Africa (cut off & isolated by the Nile?), which developed tool use (Lomekwian tools 3.3Mya) and so continued to evolve into Australopithecenes ("tool wielding stone-throwing tuber-smashing bone-crushing Savannah chimps") able to feed on more than merely tree nuts & berries (and fend off predators to which they were exposed) -- and eventually, with the advent of campfires, into ground-dwelling long-range pursuit predating homo erectus.
     
  28. tefling

    tefling Welcome New Poster

    upload_2022-8-25_18-6-53.png
    Gibbons & Orangutans (red) and "proto-Australopithecenes" (orange) all walk(ed) upright in branches. And their ranges are (were) all adjacent. The non-bipedal Gorillas & Chimps represent the farthest extreme limit of the range of apes.

    What if the original "ape" condition was Gibbon-like, Orang-like, tree-dwelling, branch-walking? Gorillas and chimps ventured into the tropical African rainforest and gorged on plenty of planty material like fruit. They grew too large for rainforest branches, and started "knuckle-walking" on the ground. They were the ones who "evolved down onto the ground", whereas proto-australopithecenes "stayed up in the canopy" like every other gibbon-orang-ape?

    Gorillas & chimps are the exceptions, ancient human proto-ancestors stayed with the "rules" and remained canopy dwelling branch walkers? (According to this picture, apes may have originated in southern or southeastern Asia, and the greatest ape genetic diversity would then be expected to exist there.)
     
  29. scotfoot

    scotfoot Well-Known Member

    You seem to be suggesting that moving to the ground produces knuckle walkers .If our ancestors were branch walkers why did they not become knuckle walkers when they evolved onto the ground?

    If you watch the track and field events at the Olympics then you will notice humans struggle to be even moderately competent at most of the events compared to animals like cats and dogs . But what we do do better than anything else in the animal kingdom is throw. That is our USP ( unique selling point ) and it requires rotation around a vertical axis.

    I remember going after chestnuts ( conkers) growing high up in trees as a small child. The options where either to climb the tree and shake the branches or to pick up a stick by one end and throw it in a slinging type action so that it spun end over end and had a good chance of hitting its target. Nobody need teach a child to do this, they will figure it out pretty quickly.

    The first effective hunting weapon would have been a stick or broken long bone ,heavier at one end than the other and slung rather than thrown in a javelin like manner. It would have completely changed the game . Spiders have webs ,angler fish have small worm like attractor projects on their heads ,archerfish can squirt water .

    In a Bonobo like, female dominated society ,along came an animal that could really rotated the trunk and throw and that's how bipedal apes got a foothold in the evolutionary tree.

    Simple, and because of that, probably true.
     
  30. tefling

    tefling Welcome New Poster

    Good point

    Chimps walk upright when carrying things

    Perhaps by the time Ardipithecus came down out of the trees more onto the ground, and evolved into Australopithecus, about 4Mya, they already had their hands full?

    Like sticks to dig tubers and stones to throw and smash bones with? (As well as armfuls of tubers and food on the way back to their central home tree? )
     
  31. scotfoot

    scotfoot Well-Known Member

    One thing I think we can be pretty sure of is that becoming aquatic will not give you a biped from a quadruped, but probably quite the opposite .

    Here is a short video of a fast moving, aquatically skilled, monkey. The bit to watch is about 1min 15 secs into the video.
     
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