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.

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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.

Originally published in news@Northeastern on May 17, 2016.