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Giant human like 30 to 90 ft tall possible or not

  1. Jan 11, 2011 #1
    Hallo all. I've got instruction from moderator to explain and share my findings on the matter. so i'm going to post the thread again.

    My question was. Whether Giant human like 30 to 90 ft tall possible or not.

    The reason why i've asked this question is that we often see some unrealistic creature in the movie. like Godzilla or flying dragons, Gulliver and Lilliput. Some time it get hard to make children realize that they are fictional character and have no realistic possibility of living ever in the history. How do we know that? we know it from the law called square cube law by Galileo. Because when you increase size of any object, it will change it's shape and other property of body like boons, blood vessel, large lunge. it will effect in heating process of large warm blooded animal. body weight will cause boons to tear down.

    But they ask then how the dinosaur lived? and if we increase the load capacity of boons. increase everything of the body then tall human would still be possible.

    would you like to share your view on this matter? I've read this links too.

  2. jcsd
  3. Jan 11, 2011 #2
    Well, no.

    You can't just 'scale up' everything in the body.

    Also, what is a boon? I assume you mean bone.

    Before this can go any further, I think you need to make some distinctions:

    Either: we can increase random factors such as bone structural strength to whatever is required - which allows anything to be possible.

    Or: we use real values for factors such as bone structural strength - which will impose limits on what is possible and so we will determine a 'maximum' when it comes to human size.
  4. Jan 11, 2011 #3


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    From earlier exchange of mails I guess it is the latter case - we know what physiology/physics tells us about bones/muscles/tissues, how large can it get?
  5. Jan 11, 2011 #4
    Well one of the biggest problems is with increases in surface area and volume.

    Surface area is a square increase, volume is a cubic increase.

    A simple example would be your lungs. The surface area of our lungs is designed to give the volume of cells in our body enough oxygen. If you increase the size of a human by a few factors the lung surface area increases slower than the volume of the body, and thus the number of cells requiring oxygen. Eventually, you would reach a point where not enough oxygen can be absorbed to sustain the number of cells.
  6. Jan 11, 2011 #5


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    Not to mention that you would have to so many other evolutionary changes to accommodate the increasing size that the organism would certainly not be human anymore.

    For instance, why do you suppose elephants have such "thick" skin? Its not a deterrent to predators, its because the enormous internal pressure created by their body fluid.

    Think of overfilling a thin-skinned water balloon. It would "burst". Elephants (or giant humans) would do the same thing if they didn't have evolutionary modifications to accommodate said size.

    To make a bipedal creature 30 to 90 feet tall (if it were possible) it certainly would no longer be human.
  7. Jan 11, 2011 #6
    before catching you guys and presenting the other problem. I would like to ask you then why people grow? when a child start growing, everything in his body start growing to support his body. if people do not stop growing at certain point say for reason of gravity to be low air become thick, then it would be still possible for human to become that large? (suppose they got the environment of the time of dinosaur)
  8. Jan 11, 2011 #7
    There's nothing to catch us on.
    The body will grow to a pre-determined set of parameters. They are specifically designed to operate under the final conditions after growth.
    If gravity becomes weaker your bones simply become weaker as they don't need to support as much load.

    Like before, things like lung capacity limit growth. Past a certain point your lungs simply cannot provide you enough oxygen. This is independent of external conditions.

    As above, your growth isn't determined by local conditions. It is in your genes. It takes a long time for those to adapt to changes in external conditions.
  9. Jan 12, 2011 #8

    thanks for staying with this post.
  10. Jan 12, 2011 #9
    Anything is possible given the right conditions.

    You mentioned dinosaurs... some of them were huge. In fact a lot of things were huge back then and became larger because of an increase in oxygen. At that time our atmosphere was loaded with oxygen and that extra oxygen was the key to life forms growing very large.

    As of right now we've lost a very large % of the oxygen that existed during the time of large dinosaurs, insects, plants and w/e else. So, because we have less oxygen we've evolved to be less massive. I would assume if oxygen levels rose on the planet significantly and steadily over a million years--- and we survived that entire time --- we'd probably be much larger in size than we are now.

    In regards to posts on 'laws', keep in mind these laws are dependent on current planetary conditions.

    HOWEVER... For a human being to naturally grow right now today to be 30 ft in size would be impossible. If it were to happen this would likely be the result of a malfunction or tumor on the pituitary gland which regulates growth hormone- this person would suffer immensely and likely die early as their genetic makeup cannot sustain the continuous growth the pituitary gland would provide.
    Last edited: Jan 12, 2011
  11. Jan 12, 2011 #10
    If we alter the organism enough to cope with the changes, certainly. But if you keep a human the same so far as physiology et al goes, it just isn't possible.
    Not sure what you're on about here, I'm assuming it's related to gravity.

    Yes, you are correct, they are planetary based. However, if you took a human and placed them on another planet with identical conditions to Earth but with half the gravity, initially the major long term issue experienced is a loss of bone strength.

    If you have a child on the other planet, they will develop under the conditions and have a weaker bone structure.

    Any immediate growth on the other planet, will be down to expansion (such as the vertebrae). It is not a permanent change and won't be that significant.

    So far as long term goes, I'm not sure. However, regardless of what the changes are over X thousand / million years of evolution, you are no longer dealing with a body under 'standard' human conditions. Once you start altering factors such as bone strength, we are no longer dealing with the question in the OP.

    This is why I specifically asked for clarification. We are either asking is it possible, under standard (current) physiological conditions or we are looking at 'what if' style questions where the physiology is allowed to change and adapt to allow for a larger creature.

    As per my first point in this post, the moment you start altering the various physiological factors anything is possible.
    Without calculation, I don't know the maximum size of a human and so can't give a definitive value.

    However, under current physiological conditions the human body does have a maximum size.
  12. Jan 12, 2011 #11

    So do you think there were large human about 30ft tall somewhere in the history of human? because I've seen some picture on Google 47 inch human femur which shows in some creationist museum. In some religious scripture, there are some lines about giant human that lived in the past. Are this true for human?
  13. Jan 12, 2011 #12
    So this is where you were going with it. Creationism and religious scripture. Not a good place for scientific discussion at the best of times.

    I've Googled it and everything seems to link to creationism in some way. I haven't found any scientific analysis of it to authenticate it. Without that, I have no reason to believe it's real.

    One thing you note with a lot of these claims, is that they won't allow anyone to study the object. I'm not saying that's the case here, but a find like this should have some analysis somewhere. If there is, I can't find it.

    To add to this, there are no pictures of the actual "47 inch femur", only models. There is no evidence that these bones actually existed.
    Last edited: Jan 12, 2011
  14. Jan 12, 2011 #13
    No, it is my interest. I would like to know the physical disadvantage and other things which will effect on survivability of animal if we scale up the size. I want to write a paper on this matter. I'm studying three books.

    Why Size Matters: From Bacteria to Blue Whales by John Tyler

    Physics of Human body by Irving P. Herman

    Physics of the Impossible by Michio Kaku

    I've just asking some random question that occurring in my head. I'll come with specific problem and other things later in the discussion.
  15. Jan 12, 2011 #14
    I assume (hope) this is a school paper? Not something to be professionally published.

    Within a specific set of parameters, there isn't really much of a disadvantage to being larger. The main problem is that you require more nutrition.
  16. Jan 12, 2011 #15
    You might have been asked by some children whether somewhere in the past there were giant human and animal as they've seen in the movie. If you tell them that human can't be that large, they would ask you then how can dinosaur become that large? So we need some sensible answer for them. We know that we did not find any fossil of human that large also our genetic record shows we were small at the past, and become taller today, not become shorter then before. but we need to find a complete answer that why it is impossible for human to become that large.

    Hope you got my stand.
  17. Jan 12, 2011 #16
    Dinosaurs are not human, in much the same way Blue Whales aren't human. Apples and oranges.
  18. Jan 16, 2011 #17
    Actually the internal surface area of lungs depends on the sum of the internal surface areas alveoli, (which is an anatomical structure that has the form of a hollow cavity. Found in the lung parenchyma, the pulmonary alveoli are the dead ends of the respiratory tree, which outcrop from either alveolar sacs or alveolar ducts, which are both sites of gas exchange with the blood as well.)

    If you increase the size of a human body by N times, The volume of lungs will increase by N^3 times the number of alveoli will also increased by N^3 times. So, the effective gas-exchange surface area will remain proportionately same. Thus there will be no problem breathing.
  19. Jan 18, 2011 #18
    Crowbird. Do you believe that there was Giant human about 15 to 30 ft tall walked on the earth and human become shorter from them?clarify your claim here pleas.
  20. Jan 18, 2011 #19
    anas101, please stop it.

    Firstly, we have exactly zero evidence of there being humans this size. So why you keep asking anyone if they believe it and for them to provide evidence is ridiculous.

    Secondly, if you want to know the maximum possible size of a human, just do some quick maths.

    In the meantime, here's something for you to read: http://www.askabiologist.org.uk/answers/viewtopic.php?id=1220
    Now, crowbird2.

    Lung volume increases, yes. However, the airway (your throat) only increases in surface area. You hit a point where you cannot get enough air into your lungs (quick enough) due to the effective constriction here. That's your first problem.

    I'll try and find the articles I was referring to relating to lung volume, they'll explain what I was attempting to say far better than I could. (Perhaps I've misread it. Regardless, the other factors still stand.)
  21. Jan 18, 2011 #20


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    The problem wouldn't be that increasing the size of lungs doesn't increase the surface area of them.

    The problem would be with ventilating lungs of those sizes.
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