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Thread: Selection Pressure and Bipedalism

  1. #101  
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    Quote Originally Posted by Paleoichneum View Post
    Quote Originally Posted by uday yadav View Post
    Quote Originally Posted by Paleoichneum View Post
    Quote Originally Posted by uday yadav View Post
    Paleochneum,


    One simple question.


    Is sacral curvature reference necessary for bipedal hypothesis?
    you have not shown that this sexually dimorphic trait is.

    If I fail to show whatever you meant by above statement, will the sacral curvature disappear/devolve?
    Please do not try to be this clueless. No matter what happens the curve will be there. You have yet to so relevance to bipedal evolution though.

    Bipedal evolution took place. My speculation is mine. Please bear with me while I try to give reasons why female sacrum curved in comparatively less.

    Battles between two human bands took place for the possession of fields of naturally growing crops. Bigger seeds (wheat, barley, corn) were perennial food useful for sedentary life style. Due to hundreds of battles, males became erect. As a male companion and in consequence, females also became bipedal.

    Females were not on the front. Had they fought the battles as aggressively as males the curve would be same as those of males. As reproduction follows survival only, more curved females would have still reproduced worthy children.
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    Quote Originally Posted by uday yadav View Post
    Bipedal evolution took place. My speculation is mine. Please bear with me while I try to give reasons why female sacrum curved in comparatively less.

    Battles between two human bands took place for the possession of fields of naturally growing crops. Bigger seeds (wheat, barley, corn) were perennial food useful for sedentary life style. Due to hundreds of battles, males became erect. As a male companion and in consequence, females also became bipedal.

    Females were not on the front. Had they fought the battles as aggressively as males the curve would be same as those of males. As reproduction follows survival only, more curved females would have still reproduced worthy children.
    The curve of the female scarum is most likely due entirely to optimal child bearing conditions of the bone structure.

    pre-humans wound not have been eating large amounts of cereal crops. I will point out the last paragraph of the article review you linked up to:
    All in all, I think this is a really fascinating study. The microbiome reveals something previously hidden, which may be important to dietary adaptations or immunity in hominoids generally. We might naturally assume that human microbiomes are products of very recent dietary innovations and rapid bacterial adaptation -- particularly among human agriculturalists. The chimpanzees may be showing that the important dynamics are much older than agriculture.
    Note the last sentence, the flora is much older then human development of agriculture.
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    Quote Originally Posted by Paleoichneum View Post
    The curve of the female scarum is most likely due entirely to optimal child bearing conditions of the bone structure.

    If curve of the female sacrum is for optimal child bearing, what for males have curved sacrum?


    Quote Originally Posted by Paleoichneum;373862pre-humans wound not have been eating large amounts of cereal crops. I will point out the last paragraph of the article review you linked up to:
    [quote
    All in all, I think this is a really fascinating study. The microbiome reveals something previously hidden, which may be important to dietary adaptations or immunity in hominoids generally. We might naturally assume that human microbiomes are products of very recent dietary innovations and rapid bacterial adaptation -- particularly among human agriculturalists. The chimpanzees may be showing that the important dynamics are much older than agriculture.

    There is no question of some mya old pre-humans ever having chance to taste rich-carbohydrate corns as they (cereal corps) evolved only before 100k years.


    Quote Originally Posted by Paleoichneum View Post
    Note the last sentence, the flora is much older then human development of agriculture.

    We are saying same thing. Flora is 100K old whereas agriculture is 10K old. For 50K to 90K years human ate naturally grown cereal crops before he understood the magic of seed germination.
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    Quote Originally Posted by uday yadav View Post
    If selection pressure played role when human became bipedal, then it certainly made women vulnerable since that time in the past and most uncomfortable today. If human became bipedal some mya, since then female human had to sit while peeing making herself easy prey and at the same time her erect partner free to flee.

    How is that possible?
    If selection pressure played role when human became bipedal, then it certainly made men vulnerable since that time in the past and most uncomfortable today. If human became bipedal some mya, since then male human had to stand while peeing making himself very visible and easy prey and at the same time his crouching partner was hidden from view and safe.

    How is that possible?
    Last edited by John Galt; December 6th, 2012 at 07:37 AM.
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    Quote Originally Posted by uday yadav View Post
    Quote Originally Posted by Paleoichneum View Post
    The curve of the female scarum is most likely due entirely to optimal child bearing conditions of the bone structure.

    If curve of the female sacrum is for optimal child bearing, what for males have curved sacrum?
    The female scarum is curved less then the male sacrum, most likely due to the lover curve amount being optimal for child bearing.


    Quote Originally Posted by uday yadav View Post
    Quote Originally Posted by Paleoichneum View Post
    pre-humans would not have been eating large amounts of cereal crops. I will point out the last paragraph of the article review you linked up to:
    All in all, I think this is a really fascinating study. The microbiome reveals something previously hidden, which may be important to dietary adaptations or immunity in hominoids generally. We might naturally assume that human microbiomes are products of very recent dietary innovations and rapid bacterial adaptation -- particularly among human agriculturalists. The chimpanzees may be showing that the important dynamics are much older than agriculture.

    There is no question of some mya old pre-humans ever having chance to taste rich-carbohydrate corns as they (cereal corps) evolved only before 100k years.
    Yes, there is question of it! What evidence are you providing that shows prehumans ate grains? Rather then larger fruits and meats that would have been much easier to gather and find


    Quote Originally Posted by uday yadav View Post
    Quote Originally Posted by Paleoichneum View Post
    Note the last sentence, the flora is much older then human development of agriculture.

    We are saying same thing. Flora is 100K old whereas agriculture is 10K old. For 50K to 90K years human ate naturally grown cereal crops before he understood the magic of seed germination.
    Who says we were eating cereals that whole time????
    If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. -Thorin Oakenshield

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    Quote Originally Posted by uday yadav View Post
    ........ I really didn’t believe someone would seriously read my posts. Thank you very much.
    The new subject I mentioned, concerned common rich-carbohydrate diet of chimps and humans.
    Carbohydrate diet comes from grains of cereal plants. Wheat, barley, corn etc.
    Human started agriculture 10,000 years ago so he would not share the outcome with chimps. This means both were used to rich-carbohydrate prior to agriculture.

    Human's and chimps gathered and ate mostly fruits and nuts, insects, and grubs. Wild grain was not very nutritious until the invention of the mortar and pestle where theirgrinding could enable more complete digestive possibilities. Domestic crops via planting and irrigation probably came much later.
    It leads us to assume that prior to domestication, cereal grains naturally grew on the land that was not exclusively in the possession of humans. Chimps somehow managed to create access to rich-carbohydrate food. At the least, chimps were living on the outskirts of human dominated territory.
    Evolution of prevotella enterotype1, 2 and 3 in chimp's gut in high abundance means from the time of evolution of densely packed ears of grains, humans and chimps shared them as food.

    The evolution of packed ears of grains (bigger seeds) cannot be more than 100K old.
    In my view, bipedal evolution is revolutionary. No minuscule disadvantage or tiny, teeny-weeny ideas like peeing etc had anything to do with bipedalism. I started by peeing problem to show that bipedal reasons were far greater than the theorists think of.
    Bipedal evolution was do or die. There was no get back, turn and run away quadrupedally. Human stood his ground. Disadvantage of leaving the battle field was not less severe than die fighting. ...................
    A number of animals and birds evolved bipedalism. In the great apes the closest to bipedal are the orangutangs. Since they are primarily arboreal this trait does not seem to be a particular advantage to them. But pre-humans that were bipedal could run faster in their hunting expeditions, and could also run faster to escape predation. When on the savannah being upright most of the time, would enable a better awareness of your surroundings concerning predators, prey, and to find other food sources. After the evolution of human bipedalism I would expect hunting to have become easier, bringing more meat into human diets. Also more cultural separation between men being hunters, and women becoming the gatherers, food preparers, and domestic servants.
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    Our arboreal ancestors were probably partly bipedal anyway. Chimpanzees or orangutan in the trees stand on their hind legs with their fore limbs over their heads to hang on to something above them. When they are on the ground, they tend to use their legs to hold most of their weight, and their hands are pressed to the ground for balance and a little of the burden of movement. But those animals can also go bipedal when they need to. Our ancestors were probably similar.

    This implies that the evolution of bipedalism was not a big change. My own view is that it was an adaptation to carrying and using tools and weapons. If you imagine our ancestors as bipeds who carry weapons, and then add a tribal society to that, so that they go out in groups, then defense is not hard to carry out. Even a lion might hesitate to attack a group of 50 individuals who all carry, and can use sharp sticks for poking and heavy lumps of wood for whacking. In addition, humans and pre-humans are pretty good at throwing rocks.

    I doubt that peeing was a problem. If a female needed to pee standing up, she would, even if it leaked down her leg.
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    All great apes are fairly slow runners, but even an average knuckle-walking chimpanzee can reach higher speeds than bipedal humans.

    Keep ignoring it all you want, but a very parsimonious origin of habitual human bipedalism on a near-vertical spine most likely started here. This is the only environment where apes and monkeys with predictability suddenly goes from four to two. Of course, this has noooo connection to human bipedalism at all, and you'd be a fool and a communist to suggest one. Let's just keep with our peacock-tails on the savannah, because then we are still fantastically special in the tree of life and therefore created in the image of G... I mean, we're still the peak of evolution, this wonderful survivalist fantasy of ours.
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    Except for the lack of a fossil record that a wading environment would provide. (eg increased fossil deposition and greater fossil concentration due to increased amounts of time in the water)
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    Quote Originally Posted by forrest noble View Post
    [

    Human's and chimps gathered and ate mostly fruits and nuts, insects, and grubs. Wild grain was not very nutritious until the invention of the mortar and pestle where theirgrinding could enable more complete digestive possibilities. Domestic crops via planting and irrigation probably came much later.

    A number of animals and birds evolved bipedalism. In the great apes the closest to bipedal are the orangutangs. Since they are primarily arboreal this trait does not seem to be a particular advantage to them. But pre-humans that were bipedal could run faster in their hunting expeditions, and could also run faster to escape predation. When on the savannah being upright most of the time, would enable a better awareness of your surroundings concerning predators, prey, and to find other food sources. After the evolution of human bipedalism I would expect hunting to have become easier, bringing more meat into human diets. Also more cultural separation between men being hunters, and women becoming the gatherers, food preparers, and domestic servants.

    It cannot be denied. There might be a period when human diet consisted of fruits, nuts, insects and grubs like other primates.
    I am trying to zero in on a period when grains became bigger and nutritious, fruits grew bigger and juicier, big meat diet replaced insect eating habit. These things took place in the absence of technology save for worthy spears and stones and sticks.
    I don’t know connection between bird and human, concerning bipedalism. It might be millions of years ago.
    Occasional bipedalism of the great apes including orangutangs did not require permanent change in their body structure. Their present sacrum bone has not undergone any remarkable evolution like humans. When human evolved to be biped, great changes happened to his body structure only comparable to even greater selection pressure.
    That is why I think human bipedalism is revolutionary. Below is my conjecture.
    Human could include big animals in his diet. 100K ago.
    Grains became bigger and nutritious. 80K ago.
    Humans became bipeds. 60K ago.
    Fruits grew bigger and juicier. 50K ago.
    Evidence. We won’t find sacral curvature in human remains prior to 60 to 70K years. We may be having technology to know the evolutionary period of nutritious grains and juicier fruits.
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    Quote Originally Posted by uday yadav View Post

    Human's and chimps gathered and ate mostly fruits and nuts, insects, and grubs. Wild grain was not very nutritious until the invention of the mortar and pestle where theirgrinding could enable more complete digestive possibilities. Domestic crops via planting and irrigation probably came much later.
    A number of animals and birds evolved bipedalism. In the great apes the closest to bipedal are the orangutangs. Since they are primarily arboreal this trait does not seem to be a particular advantage to them. But pre-humans that were bipedal could run faster in their hunting expeditions, and could also run faster to escape predation. When on the savannah being upright most of the time, would enable a better awareness of your surroundings concerning predators, prey, and to find other food sources. After the evolution of human bipedalism I would expect hunting to have become easier, bringing more meat into human diets. Also more cultural separation between men being hunters, and women becoming the gatherers, food preparers, and domestic servants.[/QUOTE]

    .........There might be a period when human diet consisted of fruits, nuts, insects and grubs like other primates. I am trying to zero in on a period when grains became bigger and nutritious, fruits grew bigger and juicier, big meat diet replaced insect eating habit. These things took place in the absence of technology save for worthy spears and stones and sticks
    .
    Granted, a good hypothesis.

    Occasional bipedalism of the great apes including orangutangs did not require permanent change in their body structure. Their present sacrum bone has not undergone any remarkable evolution like humans. When human evolved to be biped, great changes happened to his body structure only comparable to even greater selection pressure.That is why I think human bipedalism is revolutionary. Below is my conjecture.
    Makes sense. Now the reasons.

    Human could include big animals in his diet. 100K ago.
    Not unreasonable.

    Grains became bigger and nutritious. 80K ago.
    This may be more conjecture. But I like it.

    Humans became bipeds. 60K ago.
    probably at least seven hundred thousand years ago concerning homo erectus.

    Fruits grew bigger and juicier. 50K ago.
    I expect it has been that way for at least 200K years.

    Evidence. We won’t find sacral curvature in human remains prior to 60 to 70K years.

    Probably at least 700,000 thousand years before then in homo-erectus and maybe at least 1.5 million years in other species.


    We may be having technology to know the evolutionary period of nutritious grains and juicier fruits.

    possibly so.
    Last edited by forrest noble; December 8th, 2012 at 06:42 PM.
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    Quote Originally Posted by Paleoichneum View Post
    Except for the lack of a fossil record that a wading environment would provide. (eg increased fossil deposition and greater fossil concentration due to increased amounts of time in the water)
    And how exactly would that present itself any differently from the currently known fossil archive?


    Quote Originally Posted by uday yadav View Post

    Humans became bipeds. 60K ago.
    Where the hell do you get the 60k from? The skull of Sahelanthropus indicate hominid bipedalism as early as 7mya.
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    Skeleton of Turkana boy i.e. Homo-erectus without sacral curvature.




    Last edited by uday yadav; December 8th, 2012 at 10:12 AM.
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    Quote Originally Posted by CEngelbrecht View Post
    Quote Originally Posted by uday yadav View Post

    Humans became bipeds. 60K ago.
    Where the hell do you get the 60k from? The skull of Sahelanthropus indicate human bipedalism as early as 7mya.


    http://en.wikipedia.org/wiki/Turkana_Boy
    http://zinjanthropus.wordpress.com/2008/11/16/the-new-homo-erectus-pelvis-from-gona/

    Sites above, don’t say anything about sacrum that needs to be curved while bipedal evolution. If images are to be believed, Homo-erectus might have gained standing posture without any remarkable change to its sacrum. Absence of sacral curvature makes the Homo-erectus one of the many great apes but not humanlike.



    The skull of Sahelanthropus DO NOT indicate hominid bipedalism as early as 7mya.
    Upright head is no guarantee of humanlike erectness. Human had many things (skull, femur etc) of past great apes. The biggest difference occurred when to survive against great selection pressure his sacrum evolved to be curved into sacral curvature.
    HUMAN BIPEDALISM CAME FROM SACRUL CURVATURE. It happened 60K ago.
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    The Sahelanthropus skull had a spinal insert at an angle that indicated probable upright stance. But this is only probable, and definitely not certain. Sufficient doubt exists that we do not really know if Sahelanthropus was upright or not.

    However, Ardipithecus, 6 million years old, has left almost complete skeletons as fossils, and was definitely upright. So we can say that upright stance has definitely existed for 6 million years, and possibly 7.
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    Quote Originally Posted by skeptic View Post
    The Sahelanthropus skull had a spinal insert at an angle that indicated probable upright stance. But this is only probable, and definitely not certain. Sufficient doubt exists that we do not really know if Sahelanthropus was upright or not.

    However, Ardipithecus, 6 million years old, has left almost complete skeletons as fossils, and was definitely upright. So we can say that upright stance has definitely existed for 6 million years, and possibly 7.
    Tiny data error, Ardipithecus (ramidus) is estimated 4.4 million years old, Orrorin is the one listed at 6 million years. The Ardipithecus kadabba specimen is listed at 5.6 million years old, but that is only a few skeletal fragments, and bipedalism in this cannot be speculated on with much certainty (Sahelanthropus is much more certain on this account). But otherwise right, Ardipithecus ramidus is a much more certain candidate for earliest hominid bipedalism.
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    Quote Originally Posted by skeptic View Post
    The Sahelanthropus skull had a spinal insert at an angle that indicated probable upright stance. But this is only probable, and definitely not certain. Sufficient doubt exists that we do not really know if Sahelanthropus was upright or not.

    However, Ardipithecus, 6 million years old, has left almost complete skeletons as fossils, and was definitely upright. So we can say that upright stance has definitely existed for 6 million years, and possibly 7.
    Quote Originally Posted by CEngelbrecht View Post
    Tiny data error, Ardipithecus (ramidus) is estimated 4.4 million years old, Orrorin is the one listed at 6 million years. The Ardipithecus kadabba specimen is listed at 5.6 million years old, but that is only a few skeletal fragments, and bipedalism in this cannot be speculated on with much certainty (Sahelanthropus is much more certain on this account). But otherwise right, Ardipithecus ramidus is a much more certain candidate for earliest hominid bipedalism.

    CEngelbrecht @ 112. ‘The skull of Sahelanthropus indicate hominid bipedalism as early as 7mya.’
    CEngelbrecht @ 116. ‘Ardipithecus ramidus/kadabba (4.4 to 5.6 mya) is a much more certain candidate for earliest hominid bipedalism.’

    Sahelanthropus or Ardipithecus ramidus or Ardipithecus kadabba, no apes were humanlike bipeds.

    Arguing that human bipedalism is 7 mya old is not different than creationist’s argument that universe is 4000 years old.

    Skeptic and Cengelbrecht, if there was upright stance or earliest hominid bipedalism in them, that trait disappeared with them some million years ago. It has no ancestral connection with human bipedalism. We are bipeds of sacral curvature.

    Broad ilium of Ardipithecus ramidus does not imply an early adaptation to habitual terrestrial bipedality but shortage of predators.
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    uday

    I do not know where you get your "facts" from.

    There has been a continuous line of hominins who were all upright, from Ardipithecus at least through to modern man. After Ardipithecus were several species of Australopithecus - all upright as their fossils show. Then Homo habilis - also upright. Then Homo erectus - upright.

    After Homo erectus, there have been three subspecies of Homo sapiens over the past 500,000 years, also all upright. Our ancestor 500,000 years ago was Heidelberg man (Homo sapiens heidelbergensis). This ancestor gave rise to neanderthals and humans. Homo sapiens neanderthalensis and Homo sapiens sapiens.

    The fossil record shows upright and bipedal hominins from Ardipithecus around 5 to 6 million years ago, through to the present.
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    Quote Originally Posted by skeptic View Post
    uday

    I do not know where you get your "facts" from.

    There has been a continuous line of hominins who were all upright, from Ardipithecus at least through to modern man. After Ardipithecus were several species of Australopithecus - all upright as their fossils show. Then Homo habilis - also upright. Then Homo erectus - upright.

    After Homo erectus, there have been three subspecies of Homo sapiens over the past 500,000 years, also all upright. Our ancestor 500,000 years ago was Heidelberg man (Homo sapiens heidelbergensis). This ancestor gave rise to neanderthals and humans. Homo sapiens neanderthalensis and Homo sapiens sapiens.

    The fossil record shows upright and bipedal hominins from Ardipithecus around 5 to 6 million years ago, through to the present.

    I have bipedalism related facts, one of them is sacral curvature. Change in the shape of sacrum took place and human made history that became world history.

    An upright anatomy that has potential to give rise to modern human bipedalism lived unchanged for 5 to 6 million years is difficult to believe.

    It is easy to believe that our ancestor was Homo sapiens heidelbergensis, 500K ago. His upright stance made him hunter and so lived in groups. But then he little evolved until the rise of Homo sapiens neanderthalensis and Homo sapiens sapiens about 100 to 200K ago.

    And then came modern human. My argument is, only human has his sacrum curved. His ancestors have straight sacrum as any other great apes. That is why human bipedalism cannot be more than 60K years.


    PS. I read the article you pasted on your thread in anthropology.The image of homo sapiens heidelbergensis is only come from artist’s imagination. His posture suggests presence of sacral curvature which cannot be there then.
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    Quote Originally Posted by uday yadav View Post
    Quote Originally Posted by skeptic View Post
    uday

    I do not know where you get your "facts" from.

    There has been a continuous line of hominins who were all upright, from Ardipithecus at least through to modern man. After Ardipithecus were several species of Australopithecus - all upright as their fossils show. Then Homo habilis - also upright. Then Homo erectus - upright.

    After Homo erectus, there have been three subspecies of Homo sapiens over the past 500,000 years, also all upright. Our ancestor 500,000 years ago was Heidelberg man (Homo sapiens heidelbergensis). This ancestor gave rise to neanderthals and humans. Homo sapiens neanderthalensis and Homo sapiens sapiens.

    The fossil record shows upright and bipedal hominins from Ardipithecus around 5 to 6 million years ago, through to the present.

    I have bipedalism related facts, one of them is sacral curvature. Change in the shape of sacrum took place and human made history that became world history.

    An upright anatomy that has potential to give rise to modern human bipedalism lived unchanged for 5 to 6 million years is difficult to believe.

    It is easy to believe that our ancestor was Homo sapiens heidelbergensis, 500K ago. His upright stance made him hunter and so lived in groups. But then he little evolved until the rise of Homo sapiens neanderthalensis and Homo sapiens sapiens about 100 to 200K ago.

    And then came modern human. My argument is, only human has his sacrum curved. His ancestors have straight sacrum as any other great apes. That is why human bipedalism cannot be more than 60K years.


    PS. I read the article you pasted on your thread in anthropology.The image of homo sapiens heidelbergensis is only come from artist’s imagination. His posture suggests presence of sacral curvature which cannot be there then.
    Your disbelief does not trump the factual evidence that paleoanthropologists have from hip structure and skull/spine structure. homonids have been bipedial for over 5 million years.....
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    Quote Originally Posted by Paleoichneum View Post
    Your disbelief does not trump the factual evidence that paleoanthropologists have from hip structure and skull/spine structure. homonids have been bipedial for over 5 million years.....

    I searched web for paleoanthropologists who see the remains of hominids some million years ago as evidence for its bipedalism but their opinions vary. Some are positive while some raise doubts to treat them as evidence for bipedalism.

    I suspect, you are on the positive side.
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    Quote Originally Posted by uday yadav View Post
    Quote Originally Posted by Paleoichneum View Post
    Your disbelief does not trump the factual evidence that paleoanthropologists have from hip structure and skull/spine structure. homonids have been bipedial for over 5 million years.....
    I searched web for paleoanthropologists who see the remains of hominids some million years ago as evidence for its bipedalism but their opinions vary. Some are positive while some raise doubts to treat them as evidence for bipedalism.
    Yeah, but none of them would go as low as 60.000 years ago on human bipedalism. The debate these days mostly concerns either Ardipithecus r. or Sahelanthropus t. as earliest known biped, and those years are still in the millions, not thousands. Is that seriously what you mean, 60k, all based on some curvature of the spine? Or are you just trolling to prove a weird point somehow?
    "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


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    Quote Originally Posted by uday yadav View Post
    Quote Originally Posted by Paleoichneum View Post
    Your disbelief does not trump the factual evidence that paleoanthropologists have from hip structure and skull/spine structure. homonids have been bipedial for over 5 million years.....

    I searched web for paleoanthropologists who see the remains of hominids some million years ago as evidence for its bipedalism but their opinions vary. Some are positive while some raise doubts to treat them as evidence for bipedalism.

    I suspect, you are on the positive side.
    Which specific paleoanthropologists advocate for the age range YOU are suggesting? The sacrum does not in anyway impact the date at which homonids started using bipedal locomotion.
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    Which specific paleoanthropologists advocate for the age range YOU are suggesting? The sacrum does not in anyway impact the date at which homonids started using bipedal locomotion.
    The sacrum effect is a consequence of upright posture and bipedal motion on a fairly standard primate spine.

    The requirement for constant bipedal posture and motion is an upright spine. The opening to the spine/brainstem must be beneath the skull to permit upright, vertical entry. All other primates have this opening at the back of the skull. It's a very clear and simple distinction for paleoanthropologists to identify.
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    Quote Originally Posted by CEngelbrecht View Post
    Yeah, but none of them would go as low as 60.000 years ago on human bipedalism. The debate these days mostly concerns either Ardipithecus r. or Sahelanthropus t. as earliest known biped, and those years are still in the millions, not thousands. Is that seriously what you mean, 60k, all based on some curvature of the spine? Or are you just trolling to prove a weird point somehow?

    http://www.wannabe-anthropologist.com/wba_writing_pelvis.php

    Above site is decisively critical of Homonid bipedalism. A good reading for curious readers.

    CEngelbrecht,

    Sacral curvature is not some curvature of the spine.

    Sacral curvature (SC), is the angle between the first and the last sacral vertebrae, that differentiates the human pelvis from that of other animals.

    Anatomical Adaptations for Bipedalism: Sacrum
    “The sacrum articulates with both the last lumbar vertebra and the pelvis at the sacroiliac joint. The shape of the sacroiliac joint is a reflection of the lumbar curve. The sacrum is relatively broad in modern humans with large sacroiliac joint surfaces. Extant (i.e., a living species) chimpanzees have a comparatively smaller joint surface. These size differences are related to the different pattern of weight transmission through the pelvis seen in quadrupedal and bipedal locomotion. The australopithecine sacrum has relatively large, but less curved sacroiliac joint than that seen in modern humans.”

    Above para. clearly mentions that bipedal locomotion is related to sacrum. It says modern human’s sacroiliac joint is more curved. The sacroiliac joint or SI joint is the joint in the bony pelvis between the sacrum and the Ilium of the pelvis.This joint is curved little in australopithecine or Ardipithecus r. or Sahelanthropus t., and absent in quadrupeds because their sacrum is straight.

    In quadrupeds and great apes including homonids, digestive end (anus) is placed just below and at the end of the coccyx vertebrae, attached to sacrum. This arrangement facilitates defecation with least engagement and attention and has thus proved its worth in the evolutionary history of all quadrupeds.

    Neanderthals or other homonids had this arrangement.

    When human came 100K ago, his sacroiliac joint evolved to be more curved. It was exceptional evolution. Otherwise almost straight sacrum curved inside along with coccyx vertebrae, pushing the human digestive end in between thighs.

    This evolution in my view is exceptional and so revolutionary in human history. It made human erect as never before. It took place 60K ago.
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    Quote Originally Posted by adelady View Post
    The sacrum effect is a consequence of upright posture and bipedal motion on a fairly standard primate spine.

    Yes. In the absence of sacrum effect (sacral curvature), upright posture or upright spine doesn’t obstruct option of quadrupadal running.

    Constant upright posture was effect of constant selection pressure that led to evolution of sacral curvature.



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    Quote Originally Posted by Paleoichneum View Post
    [Which specific paleoanthropologists advocate for the age range YOU are suggesting? The sacrum does not in anyway impact the date at which homonids started using bipedal locomotion.

    Ashton Smith and White. There are other names mentioned in the above pasted site.
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    This evolution in my view is exceptional and so revolutionary in human history. It made human erect as never before. It took place 60K ago.
    Well then. I have even more admiration for the predecessors of indigenous Australians. They must have really been moving to get to Australia in the first place and then spread all over this huge continent so promptly within a few thousand years of this 60k marker.
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  29. #129  
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    Uday- What specifically are their arguments?
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    Quote Originally Posted by adelady View Post
    Well then. I have even more admiration for the predecessors of indigenous Australians. They must have really been moving to get to Australia in the first place and then spread all over this huge continent so promptly within a few thousand years of this 60k marker.

    Please explain why all Australopithecus fossils are found in Africa? Or have I missed something?

    In my view unless Australia was attached to main land previously, hominid fossils finding there is improbable. Human habitation in Australia took place only after discovery of agriculture and not after 60K years.
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    Quote Originally Posted by Paleoichneum View Post
    Uday- What specifically are their arguments?

    Paleoichneum,

    Ashton (1981) performed in-depth analysis of over two dozen pelvic variables for many specimens representing extant apes, H. sapiens, and Australopithecines. Of one set of ten features of inominate bones studied, including the length of the ischium, the orientation of the iliac blade, and the position of the anterior superior iliac spine, all of them showed a resemblance to great apes and a uniform lack of similarity with modern humans.

    He concludes that Australopithecines are "quite different in their overall morphology from any hypothetical creature intermediate in form between men and apes," and suggests that even though they display certain features conducive to upright posture and gait, he does not believe these features represent an earlier form on the path of human bipedal evolution.

    Kohler and Moya-Sola (1997) propose that Oreopithecus may represent convergent evolution of bipedal traits. This is certainly a possibility since Oreopithecus was isolated on the island of Tuscany-Sardinia during the Miocene, an environment void of predators. They suggest that while not a habitual biped, Oreopithecus may have adapted to standing erect for the purpose of feeding, returning to a quadrupedal mode for locomotion.

    While the pelves of early hominids differs from that of modern humans, they possess all of the traits necessary for habitual bipedalism. The differences seen in H. sapiens are the result of later adaptations necessary for the passage of a larger-brained fetus through the pelvis during birth, and do not represent refinements for bipedalism (it is even possible these changes adversely affected the mechanical efficiency of bipedal posture and locomotion).

    For details, see the following.

    http://www.wannabe-anthropologist.com/wba_writing_pelvis.php
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  32. #132  
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    In my view unless Australia was attached to main land previously, hominid fossils finding there is improbable. Human habitation in Australia took place only after discovery of agriculture and not after 60K years.
    After discovery of agriculture! Citation definitely needed for this one.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
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  33. #133  
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    Quote Originally Posted by uday yadav View Post
    Please explain why all Australopithecus fossils are found in Africa? Or have I missed something?

    In my view unless Australia was attached to main land previously, hominid fossils finding there is improbable. Human habitation in Australia took place only after discovery of agriculture and not after 60K years.
    All Australopithecus fossils are found in Africa because all Australopithecus individuals lived in Africa. The movement of pre-humans out of Africa occurred later.

    Australian indigenous people arrived between 45,000 years BP to 60,000 years BP. This was well before the development of agriculture, which was large scale with cereal crops only from about 10,000 years BP. There is a complete human skeleton found in New South Wales, dated to 45,000 years BP.
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    Quote Originally Posted by skeptic View Post
    All Australopithecus fossils are found in Africa because all Australopithecus individuals lived in Africa.
    Thank you.

    Quote Originally Posted by skeptic View Post
    Australian indigenous people arrived between 45,000 years BP to 60,000 years BP. This was well before the development of agriculture, which was large scale with cereal crops only from about 10,000 years BP. There is a complete human skeleton found in New South Wales, dated to 45,000 years BP.

    This is science forum, not political one. Pre-agriculture humans, who lived on main land at 60K or at 35K years, had no purpose to leave food abundant main land except to save themselves from winner human group enemy.

    Expeditions to find new land started only when human discovered trick of agriculture. But before that he grew on land that grew abundant food and attracted animals nearby. In New South Wales, the human remains found to be 35K to 60K years old might be of defeated humans who ran away in makeshift boats to save life but few of them reached some other lands while very few of them reached shores of Australia alive. They lived and wandered along till death and perished. Had they lived and prospered, the mere habitation would have left innumerable traces.

    Australian aborigines found Australia only post agriculture. Examination of the remains of Mungo lady, Mungo man and Lake Mungo 2 is stopped by them because they knew this secrete. In reality this is no secrete at all. Though continent, Australia is a big island where independent hominid evolution is not possible.
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    Quote Originally Posted by adelady View Post
    In my view unless Australia was attached to main land previously, hominid fossils finding there is improbable. Human habitation in Australia took place only after discovery of agriculture and not after 60K years.
    After discovery of agriculture! Citation definitely needed for this one.

    If the anthropologists fail to kill the problem of ‘sacral curvature led bipedalism’ they will face the biggest problem in human history.

    Biggest problem is here.

    Before 60K years, human lived in groups in many places on the earth. His sacrum was straight.

    If his sacrum got curved afterwards, how could this evolution take place in groups which lived all over earth?
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  36. #136  
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    uday

    Our ancestors have moved around the world, to some degree, for the roughly 200,000 years they have been in existence. It has nothing to do with agriculture. In fact, the pre-humans who existed before Homo sapiens did the same.
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  37. #137 Our bipedalism only due to evolution of sacral curvature. 
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    I propose that human erectness was flawed by straight sacrum till past 60 thousand years. Evolution of curved sacrum made us totally erect.

    This took place only 60K years ago. It was comparatively speedy evolution that spread across the globe in all human groups in spite of keeping protective distance from each other.

    I expect tremendous attack from biped theorists. Please don’t neglect and go start with your ammunition.


    Note: This item was intended to start another thread on the same topic. MERGED
    Last edited by adelady; December 12th, 2012 at 07:13 AM. Reason: merged thread
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  38. #138  
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    Quote Originally Posted by skeptic View Post
    uday

    Our ancestors have moved around the world, to some degree, for the roughly 200,000 years they have been in existence. It has nothing to do with agriculture. In fact, the pre-humans who existed before Homo sapiens did the same.

    I agree. But my subject deviates little from that.
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  39. #139  
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    Why did you start this? you have been told before not to start multiple threads on the same topic.
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  40. #140  
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    Quote Originally Posted by uday yadav View Post
    Quote Originally Posted by adelady View Post
    In my view unless Australia was attached to main land previously, hominid fossils finding there is improbable. Human habitation in Australia took place only after discovery of agriculture and not after 60K years.
    After discovery of agriculture! Citation definitely needed for this one.

    If the anthropologists fail to kill the problem of ‘sacral curvature led bipedalism’ they will face the biggest problem in human history.

    Biggest problem is here.

    Before 60K years, human lived in groups in many places on the earth. His sacrum was straight.

    If his sacrum got curved afterwards, how could this evolution take place in groups which lived all over earth?
    you have yet to show that your assertion is an actual problem. You mush provide solid evidence refuting the 4+ million years of homonid bipedalism that is known before your arbitrary 60 thousand year marker.
    If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. -Thorin Oakenshield

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  41. #141  
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    Quote Originally Posted by Paleoichneum View Post
    Quote Originally Posted by uday yadav View Post
    Quote Originally Posted by adelady View Post
    In my view unless Australia was attached to main land previously, hominid fossils finding there is improbable. Human habitation in Australia took place only after discovery of agriculture and not after 60K years.
    After discovery of agriculture! Citation definitely needed for this one.

    If the anthropologists fail to kill the problem of ‘sacral curvature led bipedalism’ they will face the biggest problem in human history.

    Biggest problem is here.

    Before 60K years, human lived in groups in many places on the earth. His sacrum was straight.

    If his sacrum got curved afterwards, how could this evolution take place in groups which lived all over earth?
    you have yet to show that your assertion is an actual problem. You mush provide solid evidence refuting the 4+ million years of homonid bipedalism that is known before your arbitrary 60 thousand year marker.

    I am not refuting any bipedal claims. I am providing a new irrefutable, indisputable, indubitable, unquestionable, undeniable theory on our bipedalism. If other theories get washed away in its presence let them be.

    As evidence we will find that human sacrum suddenly got curved 60K ago.

    Moving my new thread is a commonly found repulsion in human when faced against new irrefutable idea. It is only disguised in the form of an action. By forum rules. I give time to the moderator and others to get used to the idea that we seek truth only and stop writing on the subject for some days.
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  42. #142  
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    uday

    We have seen no evidence of any change in the human backbone 60,000 years ago. The information I have, to this point in time, is minimal differences in human skeleton over 200,000 years. Certainly nothing of any functional significance.
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  43. #143  
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    Quote Originally Posted by uday yadav View Post
    Quote Originally Posted by Paleoichneum View Post
    Quote Originally Posted by uday yadav View Post
    Quote Originally Posted by adelady View Post
    In my view unless Australia was attached to main land previously, hominid fossils finding there is improbable. Human habitation in Australia took place only after discovery of agriculture and not after 60K years.
    After discovery of agriculture! Citation definitely needed for this one.

    If the anthropologists fail to kill the problem of ‘sacral curvature led bipedalism’ they will face the biggest problem in human history.

    Biggest problem is here.

    Before 60K years, human lived in groups in many places on the earth. His sacrum was straight.

    If his sacrum got curved afterwards, how could this evolution take place in groups which lived all over earth?
    you have yet to show that your assertion is an actual problem. You mush provide solid evidence refuting the 4+ million years of homonid bipedalism that is known before your arbitrary 60 thousand year marker.

    I am not refuting any bipedal claims. I am providing a new irrefutable, indisputable, indubitable, unquestionable, undeniable theory on our bipedalism. If other theories get washed away in its presence let them be.

    As evidence we will find that human sacrum suddenly got curved 60K ago.

    Moving my new thread is a commonly found repulsion in human when faced against new irrefutable idea. It is only disguised in the form of an action. By forum rules. I give time to the moderator and others to get used to the idea that we seek truth only and stop writing on the subject for some days.
    Bullshit.

    You have provided NO evidence for any of your claims, and your proposition is contradicted by already known and understood evidence.

    The sacrum did NOT suddenly curve 60k years ago. And pretending it did is not evidence.

    There was no reason at all to create another thread that would be talking about the exact same things as are being discussed here already.
    If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. -Thorin Oakenshield

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  44. #144  
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    Why is the curve at the sacrum the most important among all the criteria, regardless of the number of millennia involved?

    I'd be really interested to find out how anyone could envisage such a large, sudden change in posture and skeletal alignment without so much as a passing mention of how this would have affected pregnancy and childbirth and the pelvis generally. If we're talking survival, the first requirement must be successful reproduction. What extraordinary conditions could possibly have allowed such a large change in the lower torso without a substantial impact on pelvic alignment and the mechanisms to support a hugely pregnant bulge?

    If anyone wants to persist with this line of argument, there are some very steep hills to climb.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
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    I think any assertion that women can't urinate standing up - or only do so messily - should be dropped from the discussion. It simply isn't true. Clothing and design of sanitary facilities may make sitting preferable for women but otherwise there's no reason that women can't urinate standing, and it will be a stream not a spray. Funnels designed for the purpose of allowing women to use male style urinals - to direct the stream in order to avoid having to remove underwear completely - have been made. But it was to avoid removing underwear and allow some ability to aim that it was addressing. No surprise that they have not been a marketing hit. There is no evolutionary pressure towards dimorphism involved in urination and would not have had anything to do with how bipedalism developed.

    I think that partial bipedal behavior arose with arboreal lifestyles - the ability to stand on tree limbs and extend reach to forage. Not necessarily a huge advantage initially to the lines of primates that had it, just taking advantage of a niche, except that the climate and landscape changed with the need to range further across the ground between forests to survive. Having those grasping hands being freed up when they were on the ground was a distinct advantage for those who took to carrying stuff and using tools. The dependence on forests for food was overcome along the way. Ultimately virtually every habitat and niche became exploitable.
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    Quote Originally Posted by uday yadav View Post
    I am not refuting any bipedal claims. I am providing a new irrefutable, indisputable, indubitable, unquestionable, undeniable theory on our bipedalism. If other theories get washed away in its presence let them be.

    As evidence we will find that human sacrum suddenly got curved 60K ago.

    Moving my new thread is a commonly found repulsion in human when faced against new irrefutable idea. It is only disguised in the form of an action. By forum rules. I give time to the moderator and others to get used to the idea that we seek truth only and stop writing on the subject for some days.
    That's one of the most absurd things I've read on this forum and that's really saying something.

    It's amazing how someone can revolutionize an entire area of study without getting out of their computer chair nowadays.
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