The prequel to Game Of Thrones, House Of The Dragon, tells the story of House Targaryen, masters of that most fantastical of creatures: giant, fire-breathing dragons. But are dragons really as outlandish as they seem? Surely no animal could grow so large and fly, or evolve the ability to spit fire? Henry Gee, evolutionary biologist and author of A (Very) Short History Of Life On Earth, says the idea is “not quite as daft as you might think”.
He cites the bombardier beetle as an example. “It synthesises a mixture of hydrogen peroxide and hydroquinone,” he says. “When the beetle is threatened, it puts the mix into a combustion chamber, and enzymes provoke the chemicals to react, producing a toxic substance called benzoquinone. It then squirts this boiling-hot liquid into the eyes of an assailant. When you think about that, producing fire is no big deal.”
Gee has a convincing theory for how a dragon would be able to burn you alive. “My scheme would be the biological synthesis of a substance that ignites spontaneously when forcefully ejected into the air. And there is such a substance: diethyl ether.”
As Gee points out (with the obvious caveat that you shouldn’t try this at home), ether is fairly simple to make – all you do is warm alcohol in the presence of sulphuric acid. “Alcohol is produced by all sorts of organisms, and living organisms produce sulphates, so it’s not too big a stretch to say that they might produce sulphuric acid,” he says. “I could imagine that there would be modified salivary glands in the dragon’s mouth containing colonies of microbes that would do just this.”
Ether also has the relatively low flash point of 45°C. “It’s so ignitable that a dragon could squirt liquid ether across its teeth and it would burst into flame.” The dragon’s skin would need to be fire-proof, of course. “There’s no reason why dragon scales wouldn’t contain something like borax,” says Gee, referring to the substance used in many fire-retardant materials.
There are, however, potential issues with the idea of spewing fire from your mouth. “There would have to be some sort of lining of the gland to prevent the dragon from poisoning itself,” says Gee, who points out that there are many animals capable of carrying poison without poisoning themselves.
“You’d also have to watch out for buildup of insoluble sulphates, which could clog up the glands and cause pain and disease.” Gee maintains, however, that there is no biological reason why creatures couldn’t evolve to breathe fire. “Just because it hasn’t happened, it doesn’t mean that it’s impossible.”
What Gee is more sceptical of is the idea that dragons the size of those in Game Of Thrones would be able to take off from the ground.
“If you watch swans or geese in their run-up, you’ll know that if they were any bigger, they wouldn’t manage it,” he says. For comparison, Gee cites the dragon’s spiritual kin: dinosaurs and ancient flying reptiles. “Some pterodactyls were as big as small planes, but they wouldn’t have been much good at flapping. Dragons are so much bigger.” Indeed, Gee theorises that some dinosaurs that were small enough to fly evolved to such a large size that flight became impossible.
“Who knows,” he says. “Maybe some of the later, larger dinosaurs were dragons that fell to Earth.”
Verdict: The bombardier beetle has nearly sussed the biology, and that’s good enough for us! Plus, we just really, really like dragons.