I've done lots of studying into gigantism. Whether it's from acromegaly or simply a quirk of genetics, humans often suffer once they reach past a certain height. There's plenty of variables of course: People with acromegalic gigantism are afflicted with numerous medical problems, and no two cases are the exact same. Even for those naturally born to grow giant, the square-cubed law is a merciless bastard that makes the current design for the human body ill-suited for being anything taller than 7 feet tall, let alone 8...

...but what about an older design? More specifically, the design of the stockier, more robust neanderthal species? They seem to tick a LOT of boxes for being better suited for gigantism than humans: They have a squatter, more robust build (better suited for heavy bodies), they have straighter spines (which may provide better support in standing) and their bones were naturally heavier and stronger than us modern humans (bone structure is among the biggest issues with giant humans).

I'm writing a character whose design is derived directly from a neanderthal build. However, the character I made is 8'3 and calculated to be nearly 700 pounds. Would a neanderthal body structure alone be able to compensate for this kind of size and weight? Or would it be necessary to make the bones more dense, like an LRP4 gene mutation? The character in question is a product of genetic engineering, and thus does NOT need to be refined for any kind of survival in the wild. It's just another story of unethical humans playing god.

Question is, would a story with this premise be realistic? Can a giant with a neanderthal's skeletal structure handle it's estimated size and weight?

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    $\begingroup$ Neanderthals were either within (for most traits) or at best very slightly outside (for a handful of traits) the normal range of variation for humans. (And whether they were a different species or just a subspecies is an ideological question.) I would say that the differences between modern humans and Neanderthals are too small to account for a functional human 2.5 meters tall and weighing 320 kg. But I'm also curious to see if somebody more knowledgeable can give an answer. Upvoted. $\endgroup$
    – AlexP
    Feb 26, 2021 at 8:00
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    $\begingroup$ The problem with giantism is that it is a specifically unhealthy growth with unproportional scaling of limbs, tissue and organs. That is one of the reasons why the health problems of people with giantism aren't the same. I dislike it if people use Giantism as proof that humans would scale bad quickly. If you set up a breeding program designed to grow ever larger humans (taking into account genetics so you prevent the genetic disease fiesta that pure bred dogs are dealing with) I suspect that the largest healthy human can grow a lot larger than people think. How large is the question though. $\endgroup$
    – Demigan
    Feb 26, 2021 at 8:23
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    $\begingroup$ What @Demigan said. Clearly there are, and have been, much larger species that humans... not many bipedal mammals, certainly, but that's kinda tangential. The good old square-cube makes sense when you're trying to construct 50m tall mecha and kaiju, but it seems rather less useful for something, say, a mere 3m tall. $\endgroup$ Feb 26, 2021 at 11:02
  • $\begingroup$ When you scale someone to twice the size their muscle cross section area x2 but mass becomes 2x2x2 which is whopping 8 folds!!! Forget mammoth's calcium rich milk there is no joint in the world to help him or her jump let alone finish marathon ;D $\endgroup$
    – user6760
    Feb 26, 2021 at 13:09
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    $\begingroup$ @user6760 well, x2 scale would mean muscle area is x4, not x2 (since area is two dimensions). And that's only if scaling is exact - evolution is often surprisingly good at scaling animals up via allometric scaling. Unfortunately most of the really crazy examples (gorilla-sized lemurs and >1000lb elephant birds on Madagascar, 12' tall and ~500-600lb moas on New Zealand) are extinct $\endgroup$ Feb 26, 2021 at 21:11

1 Answer 1


The explanation of why the square-cube law is effective at limiting the upscaling/downscaling of organisms is that the weight of organisms grows with the mass, which is proportional to the volume, thus the cube of linear dimensions, while the resistance capability of the bones grows with their cross-section, thus with the square of the linear dimensions.

If I look at the description of the anatomical difference between Neanderthal and Sapiens, I read that the more robust appearance is due to shorter bones, not to larger cross sections, especially in the limbs.

I conclude then that the problem with the cross section and the weight it can support stays unchanged.

  • $\begingroup$ You make a good point. Neanderthals indeed got their robust appearance from comparatively shorter bones. However, I was thinking of their proportions as robust rather than actual size: For example, a human that's the same height as a neanderthal will looks thinner than a neanderthal of equal height. With this in mind, I imagine a human scaled up to the height of 8'3 (like Sultan Kosen) wouldn't be as squat and robust looking as a neanderthal scaled up to an identical height, like the character I had in mind. $\endgroup$ Feb 26, 2021 at 20:39
  • $\begingroup$ I think you could have a human/near-human in this size range pretty easily with a bit of allometric scaling (wider limb bones, etc.) Maybe not from Neanderthals exactly... but OTOH there is a lot of variation in proportions within the human population, if there was a really strong selective pressure for giant size, evolution might drive toward those proportions. I do not think bones need to be super strong or anything (T. rex was a ~8-9 ton biped...) $\endgroup$ Feb 26, 2021 at 21:14

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