George R. R. Martin, the author whose bestselling series of epic fantasy novels inspired the wildly popular TV series Game of Thrones, once wrote, “Fantasy tastes of habaneros and honey, cinnamon and cloves, rare red meat and wines as sweet as summer. Reality is beans and tofu, and ashes at the end.”

What he doesn’t mention there is that fiction is often inspired by fact, that fantasy is frequently grounded in the reality of our quotidian existence, bland cuisine and all.

And that’s no more evident than in GoT itself, where a deadly poison, a disfiguring disease, and a fiercely loyal species of animal have been inspired by real world beasts, brews, and afflictions.

Here, Rebecca Certner, a doctoral candidate in the Vollmer Lab at Northeastern’s Marine Science Center, offers a look at the science behind the show’s epic fantasyland.

If you haven’t started watching season 6 yet, be forewarned, there is a spoiler included.

***

By Rebecca Certner: Greetings fellow smallfolk. Well here we are, season six, several Starks shorter and Lannisters lighter since last we spoke. Winter is, for all intents and purposes, actually here (thanks for the nightmares, child zombies) and life looks pretty bleak on both sides of the Narrow Sea. The only thing we can trust is George R.R. Martin’s eternal power to crush our hopes and dreams like that random Lannister cousin smashing beetles in the garden.

Even though Arya is blind and Gendry is probably still rowing in circles, all is not lost. Jon Snow may be undead (that little interlude wasn’t fooling anyone) but the science in GoT is very much alive. I suppose (begrudgingly) that GoT is technically fantasy, but parts of the story align quite well with reality.

 

No. 1: Greyscale

Probably based on leprosy

In the GoT universe, greyscale is a highly contagious and usually fatal skin disease that turns living flesh into cracked and stone-like scales. Those afflicted by it are called “Stone Men” and are exiled from society to live in creepy Valyrian ruins. Such poor souls can sometimes live for years with the condition before the disease attacks the internal organs and the brain, resulting in madness and ultimately death.

One can’t help but notice the similarities between greyscale and the infamous leprosy. Like greyscale, leprosy is a long-term infection that can lead to severe skin deformities. However, perhaps the greatest similarity between the two diseases is the social stigma attached to sufferers. A potential biblical mistranslation refers to a relationship between certain skin afflictions and spiritual impurity. As a result, medieval Christian communities banished lepers from their midst for fear of religious contamination. Ostensibly, GoT is based on medieval/early modern England, so this thinking aligns with Westerosi feelings about greyscale. Indeed, wildlings deem survivors of greyscale “unclean” and many people fear that the disease is merely dormant in these individuals.

However, this is where the resemblance between the two diseases ends. Unlike greyscale, leprosy is, perhaps surprisingly, not very contagious and probably not spread by touch. We know now that leprosy is caused by the bacteria Mycobacterium leprae and Mycobacterium lepromatosis rather than a supposedly polluted soul (shocking I know). M. leprae is actually among the first bacteria discovered to cause disease in humans. Both species are slow-growing and outward symptoms can take up to 20 years to develop. There is also no evidence whatsoever that leprosy infection has any effect on a patient’s mental state.

 

No. 2: Wonky seasons

Probably based on Milankovich cycles

GoT weather is rather unpredictable. (Understatement of the century.) The seasons don’t follow an annual cycle but rather last for years at a time and are totally irregular in length. This is challenging to the people of Westeros for many reasons. As a native southerner, the idea of such protracted winters is about as appealing as a date with Ramsay Bolton.

There is no solid explanation offered for the weird climate patterns in GRRM’s universe. Some in Westeros believe that in ancient times a generation-long winter culminating in a huge battle against the White Walkers had something to do with seasonal irregularities. However, this theory is mostly treated as folklore.

(I would like to preface the rest of the explanation by saying that Milankovich cycles are not a valid explanation for global warming and those who cling to this debunked theory are willfully ignorant troglodytes.)

To put it simply (because the concept is quite the opposite), Milankovich cycles are long-term variations in the Earth’s orbit, tilt, and direction of its axis that influence our climate. These small changes influence the amount of sunlight that reaches the Earth, thus leading to extended but predictable climate cycles. Milankovich cycles occur about every 21,000, 41,000, 100,000, and 400,000 years and are responsible for glacial (ice-age) and interglacial (warmer) periods.

Interestingly, this last ice age was almost responsible for human extinction. There is genetic evidence that the cold weather cut our numbers down to less than 10,000 individuals. However, we managed to come back from near annihilation around 70,000 years ago and spread beyond Africa. The same ice age around 20,000 years ago also exposed a land bridge (huge ice sheets hold a ton of water, so sea levels were really low) between Asia and North America.

In any case, it is not out of the realm of possibility that the world of Westeros and Essos has its own Milankovich cycle situation. Obviously, it would need to be far faster and more dramatic than our own, but hey, this is a planet with dragons.

 

No. 3: The strangler

Probably based on strychnine

Remember when Joffrey was killed and the world rejoiced? Good times.

That little inbred demon definitely deserved to be assassinated. And for that we must thank the strangler, a rare and deadly poison. The strangler is made from a plant found on islands in the Jade Sea. According to A Clash of Kings, the leaves from this unnamed plant are aged and then washed in lime followed by sugar water supplemented with spices. Eventually, the leaves are discarded and the remaining liquid is thickened with ash and allowed to crystallize. Like its name implies, the strangler causes the throat muscles to swell shut so the victim asphyxiates. There is also the fun little “perk” of blood leaking out of the victim’s various orifices.

If you thought such a crazy poison could only be found in fiction you’d be dead wrong (pun intended). Strychnous nux-vomica, or the strychnine tree, is the source of an eerily similar toxin: strychnine. Found in southeast Asia, seeds from this tree contain the highly poisonous alkaloids strychnine and brucine. A mere 15 minutes after ingestion, strychnine causes muscle spasms beginning in the face and neck. So far so good.

Even the strangler’s preparation matches the properties of strychnine. Instead of the fruit, lime could refer to “quicklime” or calcium oxide, a widely used chemical compound. Calcium oxide is highly alkaline which means it is very basic (has a high pH). This type of compound could easily be used (indeed it has been used) to extract alkaloids (which are also highly basic) from plant material. Another nail into the coffin (I’m on fire with these puns!) is the sugar/spice wash. Alkaloids like strychnine are really bitter so it makes total sense that you’d want to mask the taste with strong flavors like sugar and spices.

If this wasn’t already insanely cool, quicklime is thought to have been a major component of Greek fire, which is probably the inspiration for wildfire. Proving once and for all that GRRM is a secret chemist.

 

No. 4: Direwolves

Probably based on dire wolves since they ACTUALLY EXIST!

Sorry, I got a little carried away there. By exist I mean existed. Dire wolves were very much real but they are unfortunately extinct. Direwolves in GoT are pretty much just giant wolves that live in the north. That’s essentially what we know about them aside from the fact that they are fiercely loyal to their owners.

As far as I can tell, the only major difference between Earth dire wolves (Canis dirus) and GRRM’s direwolves is the proportions. In GoT, direwolves can grow to the size of a small horse. In reality, C. dirus was only slightly larger than extant gray wolves and about 25 percent heavier. Dire wolves also had a more forceful bite, perhaps suggesting that they hunted larger prey.

Like today’s wolves, dire wolves were social animals that hunted in packs. Fossil records indicate that they went extinct about 10,000 years ago along with most other American megafauna. This date coincides both with the end of the last glacial period (see Milankovich cycles) and the arrival of humans to dire wolf habitats. From this we can infer that dire wolf extinction was probably a combination of climate stress (disappearance of prey animals) and human hunting. Whatever the cause, I consider this to be a huge bummer.

So there you have it. Science continues to be an undercurrent of GoT. After all, the best fantasy is based on reality. Why make something up when real life is just as weird and amazing, if not more so. Except dragons. Real life needs more dragons.

Enjoy the rest of the season.

Certner first looked at the science of GoT during season 3, investigating the ecology of the Wall, the biology of Joffrey’s parentage, and the chemistry of Wildfire.