Giants do exist. It's just that they can't be anywhere close to being as big as those in Norse mythology or the story of Jack and the Beanstalk. The best we'd ever have for a giant was Robert Wadlow, who grew to a height of eight feet and 11.1 inches.

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People of his stature suffer the following biological and medical issues:

  • Pituitary tumor, which can get large enough to shove nerves into the brain, causing headaches and vision problems
  • Excessive sweating
  • Such sleep disorders as insomnia
  • Delayed puberty
  • Irregular menstrual periods
  • Deafness

Now let's say that the giant, as a species, does exist and grow no bigger than Mr. Wadlow. What kinds of anatomical differences from ours would they need to deal with the listed problems?

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    $\begingroup$ You do know most of these problems occurs because Homo sapiens aka humans have developed to be a certain size. Most people like you're talking about have disorders that make them so large, and cause these problems. Actual Giants would likely not have these problems. $\endgroup$ Feb 18, 2016 at 4:15
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    $\begingroup$ At the risk of self-promotion: here. This is a question I asked quite a while ago, but I think it can answer at least some of your concerns. :) $\endgroup$ Feb 18, 2016 at 6:11
  • $\begingroup$ Take a reasonably sized horse and raise it to stand on its hind legs. You've now got a creature that is approximately that size (albeit an awkward one until you do some further adjustments of its anatomy to account for the bipedaled, upright movement). What kind of anatomical differences do they need, compared to humans, to deal with the larger size specifically? $\endgroup$
    – user
    Feb 18, 2016 at 8:32
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    $\begingroup$ You are mixing cause and consequence $\endgroup$ Feb 18, 2016 at 15:11
  • $\begingroup$ Maybe it makes sense to take a look at giraffes. They are quite adapted for their height. $\endgroup$
    – Dallaylaen
    Feb 18, 2016 at 16:37

4 Answers 4


A Larger Heart

Having a large heart , especially in proportion to the giant, would counteract any negative affect associated with blood flow, hormone circulation, and lack of oxygen to the brain

Larger hormone production centers

Such as the thyroid, testes, thymus, pituitary, and adrenal glands , to increase the amount of the hormone in proportion to the body, and it may fix your puberty & menstrual issues

Thicker Bones

This will not only increase bodily support , but also ramp up the production of red blood cells. This may also solve your deafness and insomnia problem by making the bones in the inner ear more sturdy , and increasing the amount of oxygen that gets to the brain

Stronger Tendons / More Skeletal Muscle

To allow the giants to move their added skeletal weight & the added weight in general due to the square-cube law

Larger Cerebellum

Increases coordination proportionately to the larger body

More Mitochondria

Since the muscles will have to do a disproportionately large amount of work , the added mitochondria will be able to compensate

More Capillaries

Especially near the surface of the skin , to increase effective temperature regulation, ( which many other large mammals have issues with ) which fixes the sweating problem

Everything else can be scaled up normally , except for the cerebral cortex, as that might have the side affect of increased intelligence, that is , above that of the average human , but hey , if that's your intended effect , knock yourself out

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    $\begingroup$ So basically , everything in bold should be disproportionately large $\endgroup$
    – user15036
    Feb 18, 2016 at 6:29
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    $\begingroup$ They would have to be quite stocky to hold and lift their own weight and would look disproportionate to normal-sized people. This is because of course, while their muscle and bone thickness increases by the square of the size increase, their weight increases by the cube. i.e. to double their size in all directions (if they need to have the same proportions as average-sized people) would make them 4 times as strong, but 8 times as heavy. $\endgroup$
    – komodosp
    Feb 18, 2016 at 11:13
  • $\begingroup$ A good workaround from the square-cube law: have a different material for bones. Of course, this requires nature to use a new material, which she's bad at. $\endgroup$
    – PipperChip
    Feb 18, 2016 at 14:32
  • $\begingroup$ they are all not needed, they are not the resolution of the health problem rather create more problems. We move through an huge variation in size, without all that. Thats the way we evolved, and we are still showing an variations in adult size, take a Pygmy and a Zulu or a Samoan . OP is comparing apples and oranges just because they are both fruits. You cant compare a giant of myth with a medical condition that increases our size. $\endgroup$ Feb 27, 2016 at 23:34

The reason human giants have so many problems is because their systems are not designed to cope with that increased size. If they had actually been evolved to that size though then evolution would have provided solutions. After all look at the size of elephants, giants, even giraffes and horses. They all do fine being much bigger than us.

You would expect proportionally thicker legs and arms, a larger chest and heart. An obvious improvement would be to increase the secondary pumping action of our leg muscles to help lift blood out of the legs, etc.

Take a look at the adaptations in existing large mammals and it should be reasonably easy to transition the same over to humans.


What's the cause and what are the signs of a problem

Some of the problems listed are the cause for gigantism. A problem with the pituitary gland can cause gigantism and very often that problem is a tumor. The Pituitary also produce hormones that control sexual development (and related), control of body temperature, metabolism and more.

Gigantism is a condition that has a cause, the size increase is a sign of that cause. Being a giant instead would not be a condition but someone that evolved to be of a bigger size than us and in that case the health problems you listed are a non issue.


In addition to other answers, one aspect would be Gigantothermy: bigger animal tend to have higher body temperature.

Applied to a warm-blooded (i.e. constant temperature) animal, it means it would be easier keeping warm (saving calories) but also easier to overheat (limited endurance).

Human body is kind of specialized in cooling. We have long limbs, no hair and we sweat more than most (if not all) animals. So if your giant derive from homo sapiens, it would not need much adaptation; but wouldn't compare with human for long-distance running.
If he is only humanoid or derive from homo habilis, you can imagine anything.

  • $\begingroup$ This would also account for the preference of giants to live in colder climates (see the Yeti...). $\endgroup$
    – Peter S.
    Feb 26, 2016 at 17:25

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