How to create plausible giants?

[Swordfry]

I want to create a race of humanoid giants. The planet is very similar to our earth. Gravity is the same, atmosphere, etc. My giants would be 20 feet tall. The problem is, science says this is not possible. Giant mammals simply cannot exist as their bodies could not support their giant mass. The only time that was ever possible was back when earth's atmosphere was different with more of a certain gas or something. I want my books to have at least some scientific accuracy, although I classify them as science fantasy.

My giants are 20 feet tall, and I always pictured them being very lanky for giants because they are peaceful and actually quite scholarly. Not the typical fantasy giants at all. They are humanoid.

What factors could make this even remotely possible? Multiple legs? Maybe another reptilian humanoid giants (like bipedal dinosaurs...kind of)? Climate? Would a specific ecosystem benefit them more?

Let's brainstorm and figure this out.

 

[Velka]

Well, since you want to operate within the realm of science fantasy, I assume that means that it can be fantasy, but have a structured meaning behind it.

20ft. giants are fantasy, making them plausible is merely a game of world-building.

Option 1) Selective breeding; tall humanoids mated with other tall humanoids, making even taller ones. Those who were sick/crippled/met an early death due to their size were simply not seen as desired mates. Why would they want to do this? You can go anthropological and have them reach tall fruit (a metaphor) or something along the societal lines of the Potsdam Giants.

Option 2) Something in the world causing disruption to the pituitary gland (if you want to keep to the nuts and bolts of reality). Magic, climate change, industrial revolution, anything can be the cause as long as it is consistent. Are there 'average' sized humanoids? Are these giants an off-shoot or a completely different race? If they are descendants of humans, some change to environment or circumstance can cause this evolution.

Option 3) Make shit up. It's fantasy, and as long as your world has consistent rules and consequences do what you will! On their third birthday the child goes through an initiation where they drink a tea made of the ground bones of MYTHICALBIRDNAMEHERE which grants them hollow bones and therefore they aren't a victim to gravity as they normally would be. Those found lacking don't get the tea and are crushed by their own mortal weight.

Just throwing some ideas out there and seeing what will stick.

 

[Jabrosky]

My giants would be 20 feet tall. The problem is, science says this is not possible. Giant mammals simply cannot exist as their bodies could not support their giant mass. The only time that was ever possible was back when earth's atmosphere was different with more of a certain gas or something. I want my books to have at least some scientific accuracy, although I classify them as science fantasy.

Who says you can't have your world's atmosphere like the ancient earth?

I do believe bipedal humanoids as big as your giants would look stocky rather than lanky, since they'll need strong leg bones and muscles to support their bodies. But I don't see the lack of realism with your concept otherwise.

 

[arbiter117]

I'm curious as to how science says it's impossible? is it weight and bones/muscles can't support the body? Or is it that the heart can't sustain blood pressure? What part of being a mammal makes it impossible?

 

[WooHooMan]

Of the three replies above me, two of them seem to believe that it's scientifically possible so I'd be willing to guess that 2/3 of readers would believe it while the remaining 1/3 probably wouldn't care about how scientifically accurate it is. In fantasy and soft sci-fi, the scientific specifics aren't terribly important.

I got a giant that's 2,000 feet tall and my "scientific justification" for it is that he's not entirely organic and he's probably magic or something - whatever, it's fantasy. There's also a race of giants that are closer to 20 feet tall.
I've been wandering as to the ecological effect of these creatures. I've entertained the idea that the big one supports his own ecosystem either on him or in his immediate area. And the smaller ones are probably close by.

 

[X Equestris]

It's very possible for mammals to reach twenty feet in height. The giant sloth, for instance, which switched between two and four legs. It has nothing to do with atmospheric composition. You're thinking of giant insects there. It's mainly an issue of food supply. A twenty foot tall biped is within the realm of possibility. If you want to hedge your bets, you could make it alternate between walking on all fours and walking upright.

 

[X Equestris]

Also, herbivores tend to be bigger than carnivores.

 

[stephenspower]

Humanoids can only grow so tall because bone and muscle is only so strong, just as a rocket can only go so fast because at some point the weight of the fuel needed to make it go faster will actually prevent it from going any faster. Mathematically, it boils down to the fact that an increase in height of say, 2 feet, causes an increase in volume of 8 cubic feet, and that's a lot for a body to bear.

So to make giants feasible, I like your idea of making them lanky like giraffes (why do they have to be hulking beasts?). And what if they usually moved on all fours like bears, which would better distribute their weight. In addition, what if they had different bone construction just as birds do to make them lighter? You'd also have to consider their circulatory and respiratory systems, so maybe a giant has more than one heart or one which is extra efficient like a cyclist's? I don't think all this would have to be spelled out in a story to start, but their physical features would come in to play if one were trying to kill them.

 

[X Equestris]

Yeah, having them move on all fours much of the time like gorillas or bears seems the best route. Give them a proportionally powerful heart and you're set.

 

[arbiter117]

I was thinking of the giraffe which sometimes gets up to 20ft, but it's not a biped. As far as musculoskeletal strength, I feel that many creatures sport bulky bodies (elephant, kodiak) but again, mainly a 4-legged thing. I agree with X Equestris' idea of having the giants switch between two and four legs.

I've heard humans don't do well when they get taller, largely because the heart has trouble getting blood to move against gravity. To overcome that problem, a giant species might require a second heart or some way to generate blood pressure to return the blood to the heart.

If I read a book with 20-ft tall people, I wouldn't mind.

 

[skip.knox]

Science is stupid. This thread is a prime example (one of the more obscure primes) of why I write fantasy and do not write science-fiction.

[the above is meant in kindly jest]

 

[Tom]

Science is stupid.

Can I just say that this is now my favorite quote?

 

[Hainted]

It's not just weight. Your nervous system wouldn't be able to keep up with the size either. Check out the life of Robert Wadlow, who came in just shy of 9 feet, and who died of an infection caused by ill fitting leg braces. Messages form the giants extremities would be slow and dim compared to a regular sized human. I'd also advise the 3 Story graphic novels by Matt Kindt ad he details the life of a man that cannot stop growing.

 

[Terry Greer]

Robert Wadlow is an extreme case of Homo Sapiens - it doesn't prove that taller humanoids couldn't exist - only that 'without modification' humans can't really reach that height.

Giraffes are a good case in point - they have a huge number of physiological adaptations to being that tall - so it's eminently possible. The nervous system can easilly handle that length - otherwise we wouldn't have 100 foot blue whales and 50 ft long T rexes. It may need help in the form of additional encephalisation - (such as the mistakenly identified 'second brain' which is just an enlargement of the sacceral region nerves - but which does help speed up reflex actions by short circuiting the need for everything to go through the brain.

What you do have to remember is that these very large creatures have enourmous stresses and that body weight increases using a cube relationship while support (e.g. cross section bones) tend to increase using a square relationship.

So for example a creature with a body size roughly 1mx1mx2m will weigh 8 times as much as a creature with a body size of 0.5x0.5x1 metre - even though all that's happened is that the dimensions have been doubled. However if you merely double the dimensions of any cross sectional support then you've only increased the area by 4 times.

This is why large creatures have proportionally thinker legs to smaller animals of a similar type. And you cannot avoid it.

 

[CupofJoe]

The square/cube rule applies to size and mass but not necessarily weight... The bones could be made lighter, muscles more efficient and the like... more Avian than Mammalian/Reptilian in design.
I'm fairly sure that the Avian nervous system is also more efficient than either of those in Mammals or Reptiles.
This leads to a high energy form of life, so feeding a big animal now becomes even more of a factor, but if Dinosaurs [etc.] could do it...

 

[Terry Greer]

CupofJoe is right - birds tend to have have a slightly higher body temperature compared to mammals and have a concomitantly higher metabolic rate. Their bones are lighter and more structured with air spaces and their respiration is much more efficient than mammalian lungs (involving a one way system rather than our in/out lungs.). That does come with a slightly higher need for food. All those adaptations would help make something bigger.

One interesting thing is the musculature in birds and animals such as giraffe and antelopes is concentrated nearer the body with the power from muscles transferred long distance by tendons. This is why they seem to have such thin legs for their size - the leg actualy contains no muscle (apart from the upper part near the body).

 

[2WayParadox]

I second the idea of having them walk on their knuckles and feet like gorillas. That would connect them to the image of a gorilla and would also give them the bulky physique they'd need to sustain that size.

If them not being true bipedals is an issue then either ignore it or see it as a challenge.

 

[Swordfry]

I have considered making them switch between two legs and walking on their knuckles. That would help them interact with the smaller races. This giant race mostly lives away from the other races, but one is traditionally accepted into kingdoms and noble houses to act as wise men and advisors (might bring them down to 15 feet).

I was really thinking more along the lines of the Na'Vi from James Cameron's "Avatar." The Na'Vi are near 10 feet tall humanoids, but are still thin and lanky. But with no sign of weakness or emancipation. I specifically remember them saying that these people had naturally occurring carbon fibers in their bones. So I was thinking about including something like that for my giants. And there was something different about the Na'Vi compared to other creatures on Pandora. A lot, if not all other land creatures shown had multiple legs, more than four. The hammerhead rhino thing, the cat thing, and the Na'Vi's horse-like beasts.

So what made the Na'Vi so different that they could grow into tall, lanky frames, while seemingly all other land creatures there had to develop something else like two or three extra pairs of legs?

 

[X Equestris]

Pandora had weaker gravity than Earth. That's part of it. Really, I think Avatar's biology was based on Rule of Cool.

 

[writeshiek33]

ever heard of wrestler Andre the giant he had gianitist disease so might want to look that up also look him up too