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The evolution of bipedalism

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

  1. scotfoot

    scotfoot Well-Known Member

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    I recently contributed to a thread on the Arena which included some references to the development of bipedalism in our ancestors but feel that certain aspects of the original thread are worth focusing on in a separate thread .

    Specifically , I feel that bipedalism was selected for not simply to free up the hands for tool use as Darwin hypothesized , but rather to allow all of the musculature of the body to be used sequentially to develop large amounts of kenetic energy in hand held objects . In effect the human body is a power tool capable of developing large amounts of energy in a variety of hand held objects for a variety of purposes . No other animal has a similar body and this is what, together with the degree of encephalization required to make the more complex decisions which go along with high energy tool use , makes us unique .

    Many animals can run faster than us ,jump further or follow sent trails days old leading to the relentless pursuit of prey over days . But nothing on earth can throw as far or as accurately as us . (discus ,javelin ,rabbit stick )
    Also ,and perish the thought of such a conflict , but we could hit a gorilla with a baseball bat far harder than it could hit us .

    Any thoughts ?

  2. Rob Kidd

    Rob Kidd Well-Known Member

    Hi Gerry, one has to remember that Darwin was a long time ago - huge amounts of change have taken place in what might loosely be referred to as "evolutionary theory". What he had to say was very erudite in his day - about 150 years ago. The other issue one has to remember is the issue of teleology - the need to avoid any variety of teleological argument. A perfect example of such an argument would be a short necked giraffe - that looked at the leaves high in the canopy and decided to evolve a long neck in order to reach them; there is a hint of this type of though process in your construction. We are faced with several, decidedly nested, chicken and egg issues. Firstly, let us lay out the geology of the period.

    About 30 million years ago, the first eruptions of the Red Sea spread started, as always with the formation of a triple junction (peel an orange carefully so as to remain the integrity of the skin, and poke your finger through it. Notice how it tend to split in three lines - a triple junction. Over the next few million years, basaltic magma eruption will have occurred along all three lines of the triple junction. Simple geometry tells us that is cannot continue - one must "fail". Look at the map - the Red Sea and the Gulf of Aden are the two productive lines of the triple junction, the failed arm of the Red Sea spread is the East African Rift Valley, which reaches all the way to Sterkfontein in South Africa. About 10 million years ago, the Red sea started spreading in ernest, producing what we see today. In terms of climatic change, this was HUGE; it changed the climate from being warm, humid and full of trees, to a hot, dry and few trees ("The decreasing rains of the Miocene") Thus. selective pressures were huge.

    The actual results of hominid evolution are: bipedalism, with the obvious changes in the foot, vis: loss of divergent first ray and opposing big toe; midtarsal stiffness, huge calcaneus, etc.; freeing of hand for other function outside of ambulation, and encephalisation. One could argue forever about the batting order, but most would agree that at least a degree of bipedal habit occurred first; early fossil specimens would suggest a sort-of bipedal habit in the absence of a large brain.

    It is axiomatic that a degree of encephalisation would be required in order to drive the types of motor control that you are hypothesising, and this rather reminds me of the "killer ape" hypothesis, first put forward by Raymond Dart very many years ago, and now discredited. All evidence would suggest that early homo was a scavenger, though this does not preclude chucking a rock etc at quarry in order to eat.

    The other issue that has not been mentioned is that encephalisation was very expensive re: energy, which equates to heat. Certainly there is hard evidence of increased cranial venous (and other) drainage vis: cooling; however one should not ignore that it is about 5' cooler 1.5m off the ground than at ground level: thus the bipedal habit lent itself to the encephalsisation process. Notice that this was not a teleological argument: first one stood up, and then took advantage of new circumstances.

    In summary, consensus suggests that the lack of trees, strongly selected for ground level living, which then selected for the bipedal habit, which in turn selected for the encephalisation process. What use we made of our free forelimbs: who knows?

    I have been studying this stuff for 40 years' I often wonder if I know anything at all................................!

  3. scotfoot

    scotfoot Well-Known Member

    Hi Rob
    My understanding is that today's gibbon arose via speciation events about 17 million years ago . My theory (and that of many others ) is that at a later stage of evolution speciation again produced an ape with a gibbon like phenotype and that this animal gave rise to the first hominins .

    For this theory to work , a heavily forested area would be required as a habitat to produce ,through brachiation ,a gibbon like phenotype from the more Pan like common ancestor . A loss of trees through great climatic change would would then force our ancestors to the ground as bipeds .

    The pelvic adaptations required for brachiation would then be crucial in allowing the whole body to develop power which can then be applied to a hand held object . ( The anatomy of the chimpanzee does not allow for the development of the whole body rotational movements, generated initially in the legs , and which lead to high speed tool delivery .

    So we now have an early hominin capable of using sticks and rocks in a far more effective way than present day old world monkeys and chimps .Greater encephalisation would then allow these early homonids to better utilise the tools available to them and give them a greater ability to live and reproduce successfully since they would be capable of catching prey species that other great apes could not .
    In addition such animals might be better able to defend themselves against predators or competing species but this does not mean that the prime evolutionary driving force need be aggression and violence . I think it was Roosevelt who said " Speak softly and carry a big stick ; you will go far " . You don't need to use the stick to deter .

    An experiment ,which for safety reasons should probably never be carried out ,would involve teaching captive gibbons to use sticks to collect food by hitting a hanging pinata type object filled with goodies . Could they be taught to do this and would there be any carry over in to their other behavior patterns ? Would they begin throwing the sticks ?

    Last edited: Oct 28, 2017
  4. Rob Kidd

    Rob Kidd Well-Known Member

    You may well be correct. What I can comment on this. All the work that I have undertaken on the fossil record clearly demonstrates arboreal/terrestrial adaptations. I have found no evidence at all for any variety of knuckle walking (ie Pan/Gorilla) intermmediatry. That is, in some shape or form, we came down from the tree and walked away.

    I very erudite colleague (and friend) of mine relatively recently completed his PhD on a rethink of the role of hydro ambulation - ie some variety of aquatic ape hypothesis. Be clear, No one is suggesting that the proto Homo emerges from the water. What Algis is saying is a very reasonable stance. That is, in the decreasing rains of the miocene, tree number dwindled - but where were these trees? On the edge of water.... Thus the first tentative steps towards terrestrial bipedalism, may well have been in water. In case you want to read him more, I am referring to my mate Dr Algis Kuliukas PhD (University of Western Australia).

    Now think about what we do know (and has been published in refereed journals vis: The Journal of Human Evolution, The Journal of Comparative Human Biology and Science. Also in The Foot and JAPMA (refs at the end), is that the transition from an archetypal ape foot to that of modern homo took place in the following manners (grammar?) 1) Caudo-cranial (~lateral-medial) to the midtarsal joint - the calcaneo cuboid joint became humam-like before the talo-navicualar joint; 2) Disto proximal - the forefoot was human-like before the hindfoot (ie the divergent first ray/opposing big toe disappeared before the weightbearing hindfoot appeared), and 3) Dorso-ventral (arch formation) changes: the fossil record is inadequate to be definitive on this but it is likely that the anterior portion of the long arch occurred way before the posterior portion.

    Now think about the biomechanics of weightbearing ambulation in water: and abducted foot with a stable lateral column that digs into the sandy substrate.... - fits, doesn't it?

    You may also like to note that the three essential changes noted above are in fact a morphometric expression of our genetics; 1) Sonic Hedgehog genes; 2) Hox genes, and 3) Wnt systems. Oh, and of course their upstream and downstream qualifiers. That is, we are able (with some pretty complex multivariate studies, see the morphometric expression of our genetics in fossil assemblage that are several million years old.

    Food for thought?



    – Zipfel B., DeSilva J.M., Kidd R.S., Carlson K.J., Churchill S.E., Berger L.R. 2011 The Foot and Ankle of Australopithecus sediba. Science 333 1417-1420

    – Kidd R.S and Oxnard C.E. 2005. Little Foot and Big Thoughts – a Re-evaluation of the Stw573 Foot from Sterkfontein, South Africa. Journal of Comparative Human Biology 55:3 189-212

    – Kidd R.S., O’Higgins P. and Oxnard C.E.. 1996. The OH8 Foot: a reappraisal of the functional morphology of the hindfoot utilizing a multivariate analysis. The Journal of Human Evolution. 31: 269-291

    Also reported in these book chapters:

    – Kidd, R.S. On the Nature of Morphology: Selected Canonical Variates Analysis of the Hominoid Hindtarsus and Their Interpretation. In: Shaping Primate Evolution. Anapol, German & Jablonski (Eds.) pp.162-92. Cambridge University Press. 2004.

    – Kidd, R.S. Individual and Integrated Analyses of Tarsal Morpology: A Case study in Humans In: The Causes and Effects of Human Variation. Henneberg M (Ed.) pp. 61-81. Department of Anatomical Sciences, The University of Adelaide 2001.

    – Kidd, R.S. Patterns of Morphological Discrimination in the Human Talus: a Consideration of the Case for Negative Function. (Kidd & Oxnard) In: Perspectives in Human Biology Volume Three: Human Adaptability: Future Trends and Lessons From the Past. Oxnard & Freedman (Eds.) pp. 51-70. World Scientific, Singapore 1997.

    And also in these journals:

    – Kidd R.S. 1999. Evolution of the Hindfoot: A model of Adaptation with Evidence from the Fossil Record. Journal of the American Podiatric Medical Association 89: 2-17.

    – Kidd R.S. 1998. The Past is the key to the present: Thoughts on the origins of human foot structure, function and dysfunction as seen from the fossil record. The Foot 8: 75-84.
  5. scotfoot

    scotfoot Well-Known Member

    Rob , I am obviously far less knowledge than you on the subjects under discussion and perhaps sometimes see things more simply (incorrectly ?) because of this . I will look at the references you have given (where I can get access ) and look forward to reading Dr Kuliunas's theses .

    My immediate thoughts are that an aquatic ape is more or less defenceless when wading in coloured heavily vegitated water . Such animals would likely end up as food for crocodiles long before bipedalism was selected for .

    As far as evolutionary theories go I think a lot of scientists try to squeeze and muscle hippopotamus feet into size 3 glass slippers before claiming to have found Cinderella . My own favouite is the genital display theory . Are they serious ?

  6. Rob Kidd

    Rob Kidd Well-Known Member

    Genital display theory?I think not! Do keep talking; human evolution, just like all other evolution, is not an issue of debate (vis is it?); it is an issue of debate vis: mechanisms and timing.
  7. Rob Kidd

    Rob Kidd Well-Known Member

  8. scotfoot

    scotfoot Well-Known Member

    Ok ,will do . Thanks .
    My first question about costal dwelling aquatic apes is what do they gain from wading ? If you want to collect shell fish then why not just wait for the tide to go out . Collecting shellfish at low tide is much easier and would also select against an upright, bipedal stance .

    The next question is about predators such a salties and sharks . Yes ,there may be fewer of these creatures around now due to human activities ,but a few million years ago , were you found defenceless apes splashing around in any numbers you would also surely find large predators switched on to these apes as a food source .
    Worth noting also , is that wading apes can be seen for miles by land predators viewing from the beach tree line . They would soon learn to move along the coast and simple wait for the group of hapless apes to come ashore . Easy pickings ?
  9. Rob Kidd

    Rob Kidd Well-Known Member

    My impression, from talking to Algis is that the apparent weightlessness has a large impact on energetics. If you trawl my facebook page you will find him - I am sure he will not mind you asking (tell him I sent you). I think the water masses he was referring to would be decidedly freshwater - no coastline per se involved. I know that his thesis was by publications - which means if you dig for them in the fossil record, you will find them.

    I may have been over this before in a previous post, several years ago, perhaps, but you may be interested in this. The talus has long known to be an odd bone in many ways, never mind the fact that is has no muscle insertions (a quality shared only by the incus in the middle ear). In the middle to late fifties, the Prof of Anatomy in Birmingham (UK), Lord Solly Zuckerman, said to his staff, "there is something funny about that bone, go and find out). His staff were essentially Charles Oxnard and Peter Lisowski, both of whom ended up as Profs of anatomy in Australia. This was the beginning of multivariate quantitative methods, tools that I have used extensively.

    Now I am playing an away game today, getting dinner for my grandies, so I only have some toys to play with. The attached three plots are of the first met - but it is the same in the talus, only more striking. This is a tool called "Canonical Variates Analysis" where data is moved from Cartesian space into Riemannian space (at which point the maths is tooooo clever for me), but what one is actually doing it to maximise the distance (based on morphology) between groups. Carefully selected dimensions are chosen that best represent function, and these are subjected to this particular multivariate technique.

    The first canonical variate (AKA "axis") represents the largest shape quantum and is usually size related - which may be related to sex. The second in the next biggest after the first has been removed and is usually related to shape that is about function. The third is the biggest after the first and second have been removed - and this is the clever bit, is usually shape that is not - or apparently not, related to function, but is related to phylogeny. Are the hairs on your neck standing up yet?

    Now look at the first plot. A-B = human females and males; B-C = same in Chimps; D-E = same in Gorilla; E-F = same in orangs. Each represent the group mean position of a sample size of perhaps 30.

    The first plot may not hit you over the head, but now look at plot 2 - the same with some lines dawn on it. This is a plot of the first Vs second canonical variates of the first met. Look at the line through the apes, clearly demonstrates a decreasing use of the arboreal lifestyle - and is largely size related (adult male gorilla essentially do not climb trees, they are too heavy. It clearly demonstrates a quadrupedal-bipedal shift between humans one one hand, and apes as a whole.

    That was about function; now look at plot three. Note how a line describes and connects the three species of Africal ape - yes, in this context H. sapiens is an African ape - and separates them as a group from the Asian Orangutan. Canonical variate 3 is about phylogeny.

    So from some poxy foot bone, one is able to demonstrate the degree of relativity in the hominoids...... Those hairs on your neck..... ?

    You will find this everywhere you look on the skeleton, but it is more obvious in some areas - and the talus screams at you. The fourth canonical variate (not illustrated, but I can bore you with it when I get home if you wish) demonstrates sexual dimorphism.

    Scary? I should say!


    Attached Files:

  10. scotfoot

    scotfoot Well-Known Member

    Detailed and technical stuff Rob but then the devil is often in the detail .

    Going back to my necessarily simpler theories on the evolution of bipedalism , I think that if the Aquatic ape theory has any relevance then it is in relation to sea coastlines and not bodies of fresh water . What I don't go along with is that wading in any type of aquatic environment produced early bipedalism in hominins but rather that sea shore environments may have helped climatically displaced apes ,with a gibbon like phenotype ,to survive and eventually give rise to the hominins .

    So one way of seeing things is as follows -

    At some point before the major climatic changes in East Africa some ten million years ago , the last common ancestor of of Pan and Homo took to the trees and through brachiation developed a gibbon like body . With climatic change and the loss of a heavily forested habit these apes were forced to the ground were they may have struggled to survive or where they may have reverted to a quadruped lifestyle .
    Some of these gibbon like animals , however ,may have migrated to the coast were thin strips of forested habitat could still be found . These areas would have afforded shelter but perhaps not abundant arboreal food supplies forcing theses early hominins to the ground to supplement there diets . Here , a possible ability to use their entire bodies ,from the feet up , to develop high levels of kinetic energy in hand held objects could have been the key to factor in eventually producing the entire lineages of bipedal apes .

    One example of food items they might have had access to in a coastal environment are coconut crabs . These are land dwelling and grow to a size of about nine pounds . They have no predators other than man but may have been easy meat for a club wielding , gibbon like, bipedal ape . ( bipedalism is crucial to developing power in a hand held tool . )

    The long arms of the phenotype in question would have helped these animals collect shell fish along the shoreline without the need to stoop and without the need to wade .

    The rate at which genetic variation occurs in the modern gibbons is higher than in other apes and perhaps this was true of the extinct hominin in question .
    Random variations in the genes controlling the degree of encephalisation of these early apes might have been more readily expressed and selected for in an environment rich in Omega-3 fatty acids .
    Of course there would have been a large amount of hybridization between groups of apes over a period of time but the characteristics of the specialist apes of the coastal areas might eventually come to dominate .

    Final points -
    Hair loss - not needed at coast due to storage heater effect of the water mass and a draw back due to parasitic loading .

    I would love to hear what you and Algis make of the above .

    Last edited: Nov 1, 2017
  11. CEngelbrecht

    CEngelbrecht Active Member

    Never had to be more than that. But that's still a lot more aquatic activity for Homo ancestors across a few million years than the ancestors of Pan. Maybe every once in while, there was a flash flood where some individuals drowned, and those that survived did so because they had better genes for short distance swimming, and over the millenia such traits became selected for in Homo ancestors; habitual bipedalism, near furlessness, hooded nose, tubby newborn, etc.
    The suggested scenario is not without precedence amongst simians:

    Sorry to have to give an old argument the exact same old counter: What just happened to the predators on land? If you're arguing that the mere existence of bloodthirsty predators (and lethal microbes, it's the same argument) in a specific habitat completely excludes the possibility of us having lived and evolved traits there, then we couldn't have lived anywhere. There're lions and hyenas and cheetahs and snakes in the savannah and jungles, too. We have to have existed somewhere, 'cause ... we're here.

    Again, any difference in grasslands? We have to have existed somewhere.

    I have seen arguments exactly like this for years, against any aquatic pressure on the human genome, come from people of the highest educated level. That we couldn't possibly be an old beach ape of sorts, because we would've been torn to shreads by aquatic predators, completely ignoring all the terrestrial predators, that would've done exactly the same. How is this an argument?
  12. CEngelbrecht

    CEngelbrecht Active Member

    What I've seen Algis argue, is that Homo aquaticism would've come in two stages: First in fresh water e.g. ~5mya in the hinterland of Africa, later in salt water from ~2mya with the emergence of e.g. Homo erectus starting to grow a very large hominin brain. Habitual bipedalism would've evolved first, in fresh water, and the large Homo brain would've emerged later, in salt water, due to key micro nutrients, which are almost exclusively available in salt water seafood. Algis has called it Littoral Man and Waterside Woman in the past.

    (I can recommend Human Brain Evolution: The Influence of Freshwater and Marine Food Resources by Cunnane et Stewart on this.)
  13. scotfoot

    scotfoot Well-Known Member

    To defend against a predator you have to know it's there . When on land , apes have their eyes, ears ,sense of smell and the warning cries of the other animals around them ,to alert them to danger . In coloured water , wading apes have none of these . Food for crocodiles . They would be as defenseless as a , deaf ,blind ,friendless ape in a forest clearing .

    Its also a question of time in the water and water depth . If crabs are part of an apes diet it can collect them in water not deep enough to conceal a predator . Move locations and the predators don't learn where to find it and its family . If an ape spends all day wading up to its neck the predators will eventually catch up .

    The microbe argument is clearly not the same as the predator argument . Our immune systems can learn to defend against a new microbial threat in a few days . It takes a bit longer than that for a species to develop a new phenotype .

    In my opinion ALL of the explanations for bipedalism which rely on quadruped apes repeatedly adopting a standing position , for whatever reason , are wrong and fail to understand what actually went on .
  14. CEngelbrecht

    CEngelbrecht Active Member

    It's still a weird blind spot for which predators one'd focus on. If moving about in tall grasses on the grasslands, you can't see the pack of hyena come sneaking up on you, either. At least with aquatic predators, these apes could've fled to land, if and when an attack started.

    (To illustrate using 'Jaws')

    It really isn't that complicated. All apes and monkeys wade vertically in shallow water, so it's very probable, that habitual human bipedalism would've started in that exact substrate. Likely as an exaptation to us originally descending from vertically brachiating apes with the forelimbs already adapted to manipulate the surroundings as opposed for mere stance. All the various "dry" suggestions for human bipedalism has the severe weakness, that they are completely void of analogies for such an unorthodox adaptation in other animal groups. At the least we can see the entire simian group which we belong to become predictably bipedal in shallow water.

  15. scotfoot

    scotfoot Well-Known Member

    Hyenas and other land based predators are equipped with the same senses as apes and other land based prey . Sight ,smell , hearing and ,also in some cases , with group co- operation . An ongoing contest you might say .
    An ape wading up to its's armpits has no defense against a crocodile at all . It can't see it, smell it , or hear it . Once the attack begins its over . No running anywhere for an ape clamped in a crocodiles jaws . Crocodiles are equipped , in some cases along the length of their entire bodies ,with receptors that allow them to detect chemicals in the water and underwater vibrations . They can hunt productively in pitch dark conditions . They can also swim rather well . No contest at all . It might as well be apes verses men with guns .

    With regard to the last three pictures you have provided , the wading habit has not led to a habitual bipedal stance in any of the three species shown . What do these examples that tell us about wading ?
  16. CEngelbrecht

    CEngelbrecht Active Member

    Again, what happened to the olfactory capability of hyenas and lions, also making them perfectly capable of slaughtering us in the dark? It's a rubbish cherry picking argument. We can agree, that there's no particular argument in terms of gruesome predators, that would speak more for or against us having evolved traits in shallow water or not, but in turn, it hardly completely excludes the possibility either. Predators wanting to feast on us are present in all habitats. Our ancestors must have survived the carnage in what ever habitat we evolved our unique ape traits in, 'cause we're here.

    Except for the rest of the ape pack rushing to the shore, allowing enough individuals to survive to keep the species alive. Or maybe even ganging up against the predator, if chance permits. Not without precedence either, fight or flight.

    No difference from any perceivable terrestrial scenario.

    That wading activity was never habitual for our ape and monkey cousins, though it shows the propensity for simian species to adopt that peculiar body stance in shallow water, as an exaptation from brachiating ancestry. Elephants or wildebeests don't become bipedal when wading through water, so it's a unique trait for the simian group. And wade out to pick up your food and crack open oysters using a stone in an already dexterous simian hand, do that for a number of hundred thousand years, then more and more traits comparable to those of other aquatic and semiaquatic mammal groups get selected for. That's why we're "the Naked Ape," 'cause we remained by the water, in a habitat similar to this "paradise":

    Last edited: Nov 5, 2017
  17. scotfoot

    scotfoot Well-Known Member

    Apes seek shelter in the trees at night . This is because they can't so easily see the predators at night . Seeing what is hunting you helps a lot in avoiding or fighting off the threat . Day or night , an ape up to it's neck in water cannot avoid a crocodile attack .
    Also , how do you " gang up" on what you can't see . Apes are not otters .

    As for an apes fellows "rushing to the shore " ( rushing how if they are up to their necks in water ? ) no skin off the crocodiles nose since it can only eat one at a time anyway .

    Not sure about the bottom picture .

    You must lose this argument because you seek to defend the indefensible .

    No way past crocs esp in the dry season .

    Actually, there is a question . What happened to aquatic apes when the water dried up and what little remained teemed with hippos and crocs ?
  18. CEngelbrecht

    CEngelbrecht Active Member

    So why wouldn't they retreat to land during the night? While picking aquatic foods during the day. Similar to hippos. It's not exactly being argued, that these apes would've slept in the sea. We never would've been that aquatic, before we started becoming more and more terrestrial hunters stalking big game ~50,000 years ago.

    No, they're apes, but that ape is capable of reaching the same depths as sea otters. And do.

    Somebody trained a chimp called Cooper to freedive. He managed 1 meter in a pool. While holding his hand flat across his nose to keep water from entering his cranial cavities, because chimps never evolved a hooded nose that helps keep it out.

    Exactly. And that's how the species survive. Again, no difference what so ever from any terrestrial predator.

    That right there is the suggested scenario. The one extant sapienses flee to on "vacations." Just an ethological observation.

    Ah. So how do those macaques in the above video manage to pick them oysters without being torn to shreads? And there's no way past hyena in the dry season either, again you're cherry picking gruesome predators and completely ignoring others just as gruesome.

    That's why they made the transition from fresh water to salt water ~2mya and gave rise to Homo, e.g. erectus. Less competition by the beach. And that in turn gave rise to that big brain, now being fed by key nutrients available only in saline seafood.

    Like me, you have grown up with a savannah paradigm that hasn't been tenible for decades. An anthrolopologist like Phillip Tobias has long since declared the savannah hypothesis of the 18th century tradition dead. The hominin apes known in the current fossil archive have none, none of the features attributed to grassland creatures. So by that, Tobias was right in saying, that we're back to square one. If we evolved our unique traits e.g. in woodland, we have no discernable mechanism to explain why. Those traits are so completely radical from our close cousins, Pan, Gorilla and Pongo, so there had to have been a specific selective pressure. And neither grasslands nor jungles explain it. Only if you add water does it add up, straight out of convergent evolution. Can we agree, that a mammal species shedding its fur is most often seen in aquatics?

    And stop talking about the aquatic ideas as if the proponents are arguing that we were dolphin apes. That has never made one iota of sense... but that has never being argued. It's quite obvious you've been fed the same big fat lie as everyone else, as to what this "crazy" idea is suggesting. Can we please discuss what's actually being argued, and not be stuck in Darwin-cartooned-as-a chimp? Can we discuss them beach apes and leave them mermaids to folklore?

    Last edited: Nov 5, 2017
  19. scotfoot

    scotfoot Well-Known Member

    Are you arguing that bipedalism first developed in early hominids in fresh water or sea water ?
  20. CEngelbrecht

    CEngelbrecht Active Member

  21. scotfoot

    scotfoot Well-Known Member

    So where did these early, fresh water aquatic bipeds go in the dry season 5 million years ago , before they made the transition you speak of to salt water (2 million years ago ) ?
  22. CEngelbrecht

    CEngelbrecht Active Member

    You forget the fourth dimension, Marty. Untill ~10,000 years ago, there were no dry season. The dry Saharan region is vast today, but it fluctuates back and forth between being wet and green, and dry and void, following the exact same calendar as the ice ages. And we're talking millions of years at play. These are the constantly changing landscapes, we would have evolved in, whichever one it was. At the time of Sahelanthropus 7mya, Lake Chad was some five times bigger than it is today, and Toumaï died at that lake shore.

    Sahara pump theory | Wiki


    Oligocene, 33-23mya

    Miocene, 23-5mya
  23. CEngelbrecht

    CEngelbrecht Active Member

    Again, quoting Tobias, who dug up half the known South African fossil archive.

  24. scotfoot

    scotfoot Well-Known Member

    Christian , imagine a one thousand pound , invisible lion which can run 5 times faster than a hominid , and which can bite and take a hominid back into the invisible world before its fellow hominids know what's happened .
    That's a big crocodile attack in coloured water .
  25. CEngelbrecht

    CEngelbrecht Active Member

    And then imagine a whole pack of hyenas sneaking up on the same hominid in the brush, also tearing it limb from limb. What's the difference?


    You seriously can't see you're cherry picking? Why do you only focus on aquatic predators and treat the terrestrial ones as if they don't exist? How is this not the very definition of cherry picking?
  26. scotfoot

    scotfoot Well-Known Member

    "What's the difference?" Success rate .
  27. CEngelbrecht

    CEngelbrecht Active Member

    Any particular reason why hyenas would be less successful than crocodiles? Hyenas is the one predator species in Africa, that kills the most prey.

    You seriously can't see you're cherry picking? Or is your psyche evolved to be more terrified of aquatic predators than terrestrial ones, what is this?

  28. scotfoot

    scotfoot Well-Known Member

    "Any particular reason why hyenas would be less successful than crocodiles? "
    Because even a group of chimpanzees can't defend one of their number being taken by a croc when in the water . Being about the same size they can make a fist of repelling hyenas . Why not ?

    " what is this?". Focussed scrutiny of one aspect of the Aquatic Ape Theory .
  29. CEngelbrecht

    CEngelbrecht Active Member

    Look, if you're not gonna accept physical reality, we can't have this dicussion.

  30. scotfoot

    scotfoot Well-Known Member

    Road kill ?
  31. CEngelbrecht

    CEngelbrecht Active Member

    Gee, how convenient.

    Let me rephrase: There is no argument or observation that can confirm nor rule out Homo ancestry evolving its unique ape traits living in either aquatic or terrestrial habitats, based purely on presence of predators, due to predators being present in all conceivable scenarios. The one thing we can presume is that they managed to survive somewhere, 'cause otherwise Homo sapiens wouldn't be alive today. Is that logic you can follow?
    Last edited: Nov 6, 2017
  32. CEngelbrecht

    CEngelbrecht Active Member

    Anything unreasonable in that?
  33. scotfoot

    scotfoot Well-Known Member

    Christian ,from the above quote ": table 1). Like terrestrial carnivores, crocodiles also are at rest at certain periods of the day or season; hominins would be highly aware of the prey - capture strategies of this lone predator."
    , Kathlyn M. Stewart

    What this lady is appears to be saying is that hominins would avoid letting themselves become easy meat for crocodiles . Very true . That's why they stay away from 4-5 hour swims alongside them .

    Large crocodiles eat mammals and use an ambush strategy to catch them . Sometimes , they lie in water only a foot or so deep waiting to grab prey that comes to drink at the very edge of the water and who may even have their feet /hooves still on dry land . So what happens if crocodiles no longer require an ambush strategy but can simply select swimming animals at leisure ? Fat Crocodiles .

    But can we park crocodiles for a moment and look at locomotion ? Would aquatic apes have alterations to their phenotype to cope with moving primarily in water as compared to land ? Webbed feet perhaps ?
  34. CEngelbrecht

    CEngelbrecht Active Member

    'Cause zebras and wildebeests are on the verge of extinction, I gather?


    Isn't that exactly what we have? Comparably?


    You never wondered how hydrodynamic your foot actually is, considering it's an ape foot?

  35. CEngelbrecht

    CEngelbrecht Active Member

    The human foot, as distinct from other apes, is evolved to bipedal locomotion on a vertical spine. Regardless of what ever substrate it evolved in.

    [​IMG] [​IMG]
  36. scotfoot

    scotfoot Well-Known Member

    Zebras and wildebeest are not aquatic apes !
    I was not being sarcastic . Webbing between the toes and fingers of a Pan like last common ancestor would surely be a relatively easy way of greatly improving propulsion in the water ( no skeletal changes required ) So why not ?
  37. CEngelbrecht

    CEngelbrecht Active Member

    What about them otters, then? Are they on the verge of extinction, sharing waters with crocs?

    Almost all people in the world have miniscule webbing when stretching out the thumb of the hand. Some markedly more than others. So genetically, it's in there somewhere.

    [​IMG] [​IMG]

    The foot would be a different story, 'cause that had to adapt to support the upright body posture, whether for wet or dry. 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. If selection for hydrodynamics is included, suddenly it adds up why the human big toe alligned with the others and the toes became shorter and shorter, to create less drag through the water.
  38. Rob Kidd

    Rob Kidd Well-Known Member

    In a much earlier post, I pointed at that Algis' was looking at energetics (as I understand), and one aspect of this was wading. I don't think swimming was a part of it. Thus webbing is not really of relevance. Also, if one looks at the overall proportion of the digits as a part of the total pes in eg ducks, one can see that webbing is a major investment. In H. Sapiens it it woulds be of little consequence.

    Also I pointed out in an earlier post, that the lateral portion of the midtarsal complex was "human-like" way before the medial; this lends itself to and aquatic model of ambulation in the first instance. Rob
  39. scotfoot

    scotfoot Well-Known Member

    Rob , I had a look for Algis' Phd theses , found it , and since it is over 300 pages long , put it on my to do list . However , in fresh water I simply can't see past the crocs .
    In my admittedly under researched opinion , life beside the sea seems a much better bet for an early hominid .
    So at the moment my most probable evolutionary pathway for hominids is as laid out in post #10 .
    Basically ,brachiation ,loss of habitat then off to the beach as a club swing ,ground up kinetic , bipeds .

    Its interesting how much we enjoy hitting things with sticks . Pastimes enjoyed by many include golf , cricket ,baseball ,tennis , squash , badminton and hockey .
    And human feet do not gain traction by curling the toes and" digging in " during toe off .
  40. scotfoot

    scotfoot Well-Known Member

    Pondering a little further , wading in shallow sea water and picking shellfish from the sand would actually be harder work for most bipeds than quadrupeds since they have to bend over to reach the ground . This type of activity would not facilitate the evolution of bipedalism . However ,if the biped in question had very long arms then collecting food from the sand would be energetically far easier . Which brings us back to the gibbon like animal I have been talking about .

    Also , recent slow motion filming has shown that the human foot is actually more flexible than the more robust chimpanzee foot at toe off . The foot of our gibbon like hominin , which may have been the first ancestor not common to Pan and Homo , would also likely have been more flexible that of Pan .That ,together with the the already demonstrated potential of a true gibbon foot to store elastic energy , might be a further clue as to our ancient origins .

    It is starting to look to me that a gibbon like stage in our evolution is more likely than not .

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