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Thread: The Evolution of Hominid Bipedalism

  1. #1 The Evolution of Hominid Bipedalism 
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    Palaeoanthropology is a mainstream science. It is concerned with the fascinating subject of human evolution. Ever since Darwin and Wallace enlightened us with the theory of natural selection, scientists have been seeking explanations of those phenotypic traits which distinguish us from our great ape cousins which are consistent with that theory and plausible in terms of the fossil record, and the whole gamut of evidence from comparative biology, the likely paleohabitats and so on.

    There are several human characteristics which clearly distinguish us from chimpanzees, bonobos and gorillas. Perhaps the most fundamental, and almost certainly the first chronologically, is our adoption of obligate bipedalism. The African great apes, chimps, bonobos and gorillas are predominantly knuckle-walking, the other clade of great apes, orang-utans are quadrumanous (fist walking) - they are all largely quadrupedal.

    In the 150 years or so since Darwin/Wallace, around 30 separate ideas have been published to explain this peculiar phenomenon, although they can be grouped into various broad categories.

    I propose that the relative merits of these models be discussed in this thread. Specifically, I would like feedback from scientifically minded impartial people about why the wading hypothesis has been largely overlooked by the field in the last 50 years or so. Although several of these ideas almost certainly played a part, I think the wading hypothesis is the strongest on its own because it is the only one of which this can be said...

    "Place a group of extant great apes in scenario x and they will all move (not just pose momentarily) bipedally, unsupported, for as long as the conditions prevail. It might kill them if they tried to continue moving quadrupedally. No other Mammalian taxon shares this peculiar switch."

    Let's consider, from the vast literature on this subject, what "x" could be.

    "x"
    Forelimb Pre-emption (carrying)
    General freeing of the hands
    Carrying food back to gallery forest bases.
    Carrying and scavenging
    Migration-carrying hypotheses
    Male provisioning
    Female driven infant carrying
    Weapon Throwing
    Tool carriage
    Weapon wielding
    Social Behaviour
    Nuptial gifts
    Inter-specific threat displays.
    Intra-specific threat displays
    Sentinel behavior (peering over the savannah)
    Phallic display directed at females
    Copied gimmick idea
    Feeding
    Seed Eating
    Terrestrial squat feeding on the forest floor
    Other gathering
    Postural feeding hypothesis
    Arboreal predation
    Stalking
    Specific Hunting
    General scavenging/hunting
    Habitat Compulsion (Wading)
    Coastal foraging
    ‘Aquarboreal’ model
    Amphibische Generalistentheorie
    River apes
    Wetland foraging
    Habitat Compulsion (Climbing)
    Hylobatian (Brachiator ancestor) Model
    ‘Upwardly mobile’/vertical climbing hypothesis
    Orang-utan-like hand assisted bipedalism
    Variability selection hypothesis
    Walking on snow or mud
    Energy Efficiency
    Slow, long-distance walking
    Biomechanical inevitability
    Efficiency of moving from tree to tree
    Locomotor de-coupling
    Endurance running
    Other
    Thermoregulatory hypothesis
    Iodine deficiency
    ‘evo/devo’ mutation
    Multi-factorial



    Which of the other models can offer such a simple, plausible, means of inducing bipedalism in our hominid ancestors?

    Algis Kuliukas


    Last edited by Algis; October 16th, 2011 at 03:05 AM. Reason: Table got screwed up
    If you want discuss ideas like this...

    Waterside hypotheses of human evolution:
    Assert that selection from wading, swimming and diving and procurement of food from aquatic habitats have significantly affected the evolution of the lineage leading to Homo sapiens as distinct from that leading to Pan.

    ... in a forum where the mods are not complicit in shouting the idea down by mob rule, try going to waterside-hypotheses.com.
     

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    MSG
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    Hey, hi Algis - nice post!

    I was reading your post about savannah theory, and how as the climate dried out (sorry if I have this mixed up,) the apes were crowded in near the waterways? Is that the gallery forests you were talking about? Is there a way to tell whether the apes were living close to the water from their fossils?


     

  4. #3  
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    This sounds to me an attempt to get another aquatic ape thread going.
    This theory has been pretty much dumped by professionals, for a number of good reasons, and if the thread continues, no doubt all those reasons will once more be paraded.
     

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    Quote Originally Posted by skeptic View Post
    This sounds to me an attempt to get another aquatic ape thread going.
    This theory has been pretty much dumped by professionals, for a number of good reasons, and if the thread continues, no doubt all those reasons will once more be paraded.
    Thanks. I'm very interested to read that, as it is the subject of my PhD. Please could you cite me the paper where it was "dumped" as I haven't managed to find one, or any of the "good reasons" why you think it was dumped.

    Perhaps the only "good reason" you will come up with is it's unfortunate association with the mislabelled, misunderstood and misrepresented "aquatic ape".

    Algis Kuliukas
    If you want discuss ideas like this...

    Waterside hypotheses of human evolution:
    Assert that selection from wading, swimming and diving and procurement of food from aquatic habitats have significantly affected the evolution of the lineage leading to Homo sapiens as distinct from that leading to Pan.

    ... in a forum where the mods are not complicit in shouting the idea down by mob rule, try going to waterside-hypotheses.com.
     

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    Quote Originally Posted by MSG View Post
    Hey, hi Algis - nice post!

    I was reading your post about savannah theory, and how as the climate dried out (sorry if I have this mixed up,) the apes were crowded in near the waterways? Is that the gallery forests you were talking about? Is there a way to tell whether the apes were living close to the water from their fossils?
    That model of climate is severely oversimplified, because early and mid Pliocene is marked by wide variations in climate even as it has been during the late period. It might have slowly cooled and gotten drier, but it was hardly smooth. First when did this wading happen. Most of Africa, particularly Southern and Eastern Africa were a lot wetter than today up until at least 3 million years ago--about the time our IQ apparently takes off and we start using tools etc. There are more rivers to cross in wet conditions. But lets say for the sake of argument it is after that period. Fewer rivers. Antelope, Wilderbeast and other fauna tended to group near their banks. That's a benefit for early humanoids perhaps who like other predators hang out there--but like other predators, other than swimming or fording once in a while, we don't need to go into the water much at all to do so. The water is also muddy, not much good for collecting fresh water shells or spear fishing.
    Meteorologist/Naturalist & Retired Soldier
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    since the thread's title is "The Evolution of Hominid Bipedalism", i'll throw in my 2 cents worth of comment
    i've always been fascinated by the fact that the timing of the arising of bipedalism may well coincide with that of the Messinian salinity crisis

    could this have been the environmental trigger that made bipedalism an advantageous trait ?
    i also should mention that i'm a great believer in Stephen J Gould's concept of exaptation, where traits evolve for one reason (or maybe not even for any particular reason) and then get used in a different adaptive framework by natural selection - using that line of reasoning my thinking is that bipedalism already existed in a (semi-)forested environment, but became favoured as an advantageous trait as the result of an environmental change
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
     

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    Forum Bachelors Degree CEngelbrecht's Avatar
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    Quote Originally Posted by skeptic View Post
    This sounds to me an attempt to get another aquatic ape thread going.
    It is such an attempt, let's not kid anyone.

    Quote Originally Posted by skeptic View Post
    This theory has been pretty much dumped by professionals, for a number of good reasons, and if the thread continues, no doubt all those reasons will once more be paraded.
    My experience now is that it is largely dumped by professionals today because of a horrid prejudice and misinterpretation of it's actual suggestion. I recently had a phone conversation on this 'aquatic' topic with a friend of mine with a degree in natural sciences (though not anthropology). And even he was suffering from this prejudice: That what Alister Hardy suggested in 1960 as a speculative human ancestor was a 'sea ape'. For a long time, I thought that this was indeed his suggestion, being the only presentation of this idea that I could find at the time. This would indeed be folly based from observation. The way the topic has been presented by Elaine Morgan as some sort of 'beach ape' (a term coined by a freediving friend of mine) has always seemed much more reasonable.

    When I finally did get access to his 1960 New Scientist article Was Man More Aquatic in the Past, I realised that not even Hardy suggested a sea ape. It more and more occurs to me, that something has gone horribly wrong in the debate about this 'wet' idea since day one. If only people would read those four pages before they pass judgement. They don't even have to read its entirety, they just need to scroll to the third-last paragraph:
    Perhaps, in time, some expedition to investigate tropical Pliocene (coastal) deposits may yet reveal these missing links.
    But aparently, this is too much to ask of human complacancy. This four page article has been misquoted, misinterpreted and misrepresented countless of times in ways not even Johnny Cochran can keep up with, in particular by Jim Moore on his site aquaticape.org. Horridly, I see some academics refer to this site, and having read it now in detail and compared it with many of the original source texts, this site now strikes me as a brutal character assassination with no room for decent scientific review or even method. For instance, Jim's text still claim in mocking language, that Hardy claimed that his coastal ape lived 20 million years ago, which I still haven't found with a single word in the available litterature by Hardy. In fact, in the above quote he mentions the Pliocene as a time frame (3-5 mya), which is still not unreasonable by any contemporary concensus in paleoanthropology. And this is only one such example and has left me to doubt every single paragraph on this widely referred site. This site alone is an embarassment to contemporary science, I'd say.

    The prejudice against this wet option in human evolution has proven incredibly hard to penetrate, even among better educated people. The human skull is indeed inches thick.

    And I think I now know why. Desmond Morris is the one to coin the term 'aquatic ape' in his brief and neutral presentation of Hardy's thesis in his book 'The Naked Ape', a bestseller from 1967. Hardy never called it that, but it reached wide use and was taken over by Morgan in her writings. This term must somehow give people a fallable impression of a 'Dolphin Ape', which there are no serious indications of in neither extinct or extant humans, but which has never (never!) been presented by any serious aquatic ape proponent. But the 'beach ape' suggested by Hardy definitely have a lot of serious indications worth applying increased scrutiny, and this with, I daresay, scientific enthusiasm. And yet, this is indeed not the case today, but if skeptics are refered to sites like aquaticape.org without access to the source texts in question, how the devil can they make the correct assessment?

    Algis makes the case, that the term 'aquatic ape' is mislabeled and should be dropped and replaced. I would respectfully disagree. This term has existed since Morris, and has as such grown into established scientific language on the topic. The various misconceptions and prejudices and low browed mockings has nothing to do with the content of the argumentation (provided that they are actually being read) and should as such not govern its use based on 'mob rule'. So why disguise the term, as if we need to be embarrased by supporting the idea in one form or another? Why should we run and hide as if from the Catholic church with the writings of Copernicus? We all know what we're talking about: Hardy's suggested coastal proto-human as expanded by Morgan et al.
    And besides, a group of species like the hippopotamuses, which can be labeled a 'beach cow', are defined by contemporary zoology as an 'aquatic mammal' (as opposed to 'marine mammal', this at the center of the prejudice). In terms of habitat, the said aquatic ape would be comparable with this group, in either salt or fresh water or perhaps both. Etymologically the term 'aquatic' would then still match the suggestion (as it actually is, and not in some wishful misinterpretation). Perhaps that was why Morris used it.


    Did I mention that the AAT/H/Wading/Amphibious hypotheses does not talk about a sea ape?
    And never has?
    That it talks about a coastal ape as a potential human ancestor?
    A "beach ape"?

    Is it clear enough now?
    Last edited by CEngelbrecht; October 16th, 2011 at 05:07 PM.
    "The suppression of uncomfortable ideas may be common in religion or in politics, but it is not the path to knowledge, and there's no place for it in the endeavor of science. (History) shows us clearly that accepted and conventional ideas are often wrong, and that fundamental insights can arise from the most unexpected sources."
    - Carl Sagan, 1980


     

  9. #8  
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    I moved the AAT thread to pseudo. You may disagree with that decision, but to ignore it and start a new thread is obviously not acceptable. I'm going to lock this thread now, though I can merge these posts into that thread if requested.

    Algis, please consider this a first warning.
     

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