The anatomy of giants in 'Game of Thrones': did they get it right?

Every now and then a giant shows up in the television series Game of Thrones. Obviously, GoT is not a nature documentary so there is no reason to be difficult and analyse it scientifically. After all, it has dragons that cannot fly but do. But as their eggs only hatch after having roasted in a funeral pyre there is magic involved, and that should do the trick. Still, every time a giant ambles across the screen, the science routines in my mind spring into action and start wondering about its anatomy.

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The giants do not just look tall but broad as well, and that makes sense. Their legs seem extremely broad and columnar, as wide as the feet. The feet do not even stick out much in front, unlike ours. The outer shape of the clothing suggests that the giant has feet like an elephant, with toes and a big elastic pad in the sole, all encased in a cylinder. But all those rags and furs hide the giant's shape so it is hard to tell. Perhaps the actor is standing on high heels or stilts to add some height, and the wide trouser legs are meant to hide that. The leg/foot assembly does look rather long.

So every time I see a giant I think: 'That looks convincing; I wonder whether they asked some biologist how to make a giant'. And then of course my attention is diverted away from that by someone being murdered unexpectedly in a gruesome manner; it's GoT, after all. In this series people die all the time, and with some recent story developments they might even do so more than once. Recently (series 6, episode 7) a giant stood still in one shot, together with some puny humans. His name is apparently 'Wun Weg Wun Dar Wun', in case you wonder, or 'Wun Wun' for short. I thought I should get that frame to have a closer look, after the killing would be over (temporarily, that is).

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So here is the shot in question. The giant appears twice as tall as the man on the left, who I suppose is normal height. I estimated that man's height to be 1.8 meters, so the giant would be 3.6 m. tall. Some internet searching revealed that the actor playing Wun Wun is over 2.1 m tall. What the producers  did was to use low camera angles to simulate his size. Here is a video of that, but be warned: Wun Wun is visible for only a few seconds.

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I copied the giant, and reduced his size to what should be about 2.1 meter, compared to the 1.8 m man. I stuck him in again to get a feeling of what the actor may have looked like without special effects. Here is the result of that, including doing away with the blue overcast. It does not look as if he is walking on stilts, so the cylindrical shape of his legs is probably there to suggest just that: big legs. He looks very broad; should he? What should the proportions of a 3.6 m tall giant be like?

To find out, please read the first and second post in this blog on why body size matters. In short this is what happens if you double the length, width and height of an object or animal: its mass and hence weight will not become twice the original amount, but eight times as much. But the strength of a bone is given by its cross section, and if you only double the radius of a bone, its cross section becomes four times as large. But the bone needs to be able to support eight times the weight. This means its radius has to increase disproportionally: if the weight increases eight-fold, then the cross section needs to increase by a factor eight too. The radius needs to increase by the square root of eight, which is 2.83 times. In case you are dazzled, it boils down to this: increasing bone length by a factor of 2 means that bone radius has to increase by a factor 2.8.

Mind you, in real life that is probably not enough ('real life'?; what am I thinking here?). Muscle strength also depends on its cross section, and to keep the same relative strength means muscle cross section has to increase by a factor 2.8 as well, meaning more muscle mass. All these extra increases in bone and muscle will add mass, so the bones have to be even thicker and... You see where this is going. At some point there is no mass left for lungs, guts or brain (judging from Wun Wun's speech patterns, some savings were indeed made in the latter department). Say we use a factor 3.0 to accommodate for all that.

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Here is a nice schematic human anatomy image found on the internet. I cut it up in sections and increased the width of the sections appropriately. Well, mostly: I reasoned that the increase should certainly apply to the thickness of weight-bearing bones, such as legs and the vertebral column. I did the same for the arms as well, or the result would look silly. But in principle pelvic and thoracic width do not need an additional increase beyond the factor two we started with. I did increase them some more, if only to give thigh muscles some room.

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Here is the result of this simple attempt. Do not forget that he is twice the size of the man we started with. The resulting giant certainly looks large as well as stocky, and so he should. Note that I increased the feet a bit more, to allow all the thicker foot bones to lie next to one another, as they must. But I did not alter foot anatomy any more. Before we discuss that further, let's approximate the giant a bit more by using the body outline and adding a suggestion of clothing.

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Here it is. This is what a morphologically reasonably sound giant, twice the height of a normal man, might look like.

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And to get a feeling for size, here is the giant next to a normal-looking human on the left, half the size. The giant is not that different from Wun Wun, confirming my intuitive guess that the designers got it right. The hands look quite good. The actor must have been covered in very thick layers of padding to get the stocky look. It is not often I get to write that the television or film industry got their biomechanics right. Regular readers will know that there was little reason to be happy before; see the posts on Avatar and John Carter of Mars.

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The one remaining matter is whether the giant should have his feet examined: can he stand on human-type feet or must he have elephantine feet, as shown above? If a 1.8 meter m. tall man has a mass of 80 kg, then simply doubling the height, depth and width wil ensure that the mass becomes 8 times as much (80 x 2 x 2 x 2), so 640 kg. But remember that we chose to increase the depth and width by a factor 3, not 2, so the mass becomes 80 x 2 x 3 x3, or a colossal 1440 kg. Wow. Being bipedal, one leg will have to be able to withstand all that weight. Mind you, we already have taken that into account as far as bone strength is concerned. Still, it is a lot. But Wikipedia tells me that draft horses weigh up to 1000 kg and giraffes weigh up to 1930kg, and these animals do not have elephantine feet at all. While running just one of their legs may be on the ground at a point in time, with a lot of dynamic forces acting on the bone as well. So I do not think a 1440 kg humanoid needs elephantine feet, but that does not mean he cannot have them. All this brings up the topic of whether very large bipedal animals should have elephantine feet with embedded toes, or whether they should have free toes, sticking out. I am in favour of the latter, but that is something for another post, on toes.    

Unless the GoT designers tell us what Wun Wun's feet look like, we will never know.  Unless... unless of course we get to see a naked giant. GoT is not afraid of nudity and there have been calls for nudity to be more equally divided among male and female cast members. Perhaps that equality should include not just sexes but species, too. So let's have a naked giant; purely for scientific reasons, obviously. Actually, just the feet would be enough, thank you so much.   

Note (March 2018): I had made a mistake by stating the weight of the corrected giant as 640 kg, but that was without taking into account the additional increases in cross sectional area, as pointed out by a commenter. 

Note (September 2018): you may wish to have a look at a later post asking whether it is unethical to let giants ride on mammoths...