The Legend
Since the beginning of time, Man has been fascinated with dragons. No mighty creature, in fantasy or in perceptible reality, can compare to the giant flying serpent with rows of sharp teeth, breathing fire through its jaws; it is the beast of all beasts, the mightiest of all legendary creatures and the single most universal fantasy ever known to mankind.
From the Chinese wise and benevolent lake dragon, to the evil maiden eating European dragon, these awe-inspiring creatures are part of the mythology of most cultures in the world. Perceived in many different yet similar ways, throughout the ages and almost everywhere in the world, dragons are what one may consider a universal culture phenomenon.
In Europe, dragons are evil nightmarish fire-spewing reptiles, large and lizard-like, with the forked tongue of a snake and wings like a bat. In the ancient cultures of Mexico and South America, a divine feathered serpent known by various names was believed to renew the world after each cycle of destruction.
In the East, dragons are amphibious creatures that dwell in oceans, lakes, rivers and even raindrops. They are revered as life-giving symbols of fortune and fertility, capable of unleashing rain and spewing fire to punish evil-doers. In Ancient Egypt, sky serpents and winged dragons were well represented in the Egyptian pantheon of gods and goddesses. Meretseger (a serpent with wings) and Apep (a giant serpentine dragon and an evil god) are both representations of dragons in Egyptian mythology.
Although the depiction of dragons from different cultures conjures dissimilar images in our minds, those images are undoubtedly related; for however different qualities the dragons may possess, they are all enormous and powerful creatures who share a resemblance and a most thrilling quality; the ability to breathe fire.
Yet, however widespread the stories of dragons maybe, to this day, there exists no shred of scientific evidence that these magnificent creatures ever existed. No dragon fossils or skeletal remains were ever discovered; all that remains are numerous works of art and literature, and the legends and stories we heard as children.
While most scientists believe that dragons are the product of the rich imagination, inspired and influenced by other living creatures the likes of giant lizards, serpents and crocodiles, other scientists, undeniably outnumbered, question this notion, and some even truly believe that dragons one day roamed the Earth and might have been the last surviving dinosaurs.
Although I always tend to ally with the side that holds the most scientific evidence and living proof, this time I would like to question the science; perhaps because I am prejudiced by my own dragon fascination, but more so because realistic scientists failed to answer a most important question: If dragons were just a fantasy, why are they depicted in so many cultures, at a time in history when cultures were not inter-mixed? These are cultures that never connected, or even corresponded with each other; is it reasonable to believe that they were all coincidentally and simultaneously making it up?
For a moment, I would like to explore the notion that dragons are not a mere fantasy, and to ask the science if it is theoretically possible for a dragon, or any creature for that matter, to be able to breathe fire?
The Science
To answer the question of whether any creature can evolve to possess the ability to inhale or exhale fire, one must first understand how a fire starts, and what breathing fire would require.
Fire starts when a flammable and/or a combustible material, in combination with a sufficient quantity of an oxidizer, such as oxygen gas or another oxygen-rich compound, is exposed to a source of heat or ambient temperature above the flash point of the fuel/oxidizer mix (the lowest temperature at which the mixture can vaporize), and is able to sustain a rate of rapid oxidation that produces a chain reaction. Fire cannot exist without all of these elements in place, and in the right proportions. Some fuel-oxygen mixtures may require a catalyst, a substance that is not directly involved in any chemical reaction during combustion, but which enables the reactants to combust more readily.
So, the first thing a fire-breathing dragon would need is a flammable material; in other words, a fuel. Assuming dragons could utilize coal or gasoline in their gut would be ludicrous; their fuel would have to be the result of a natural biological process that can safely take place in their gut. One plausible theory suggested by dragon proposing creationists is that dragons produced hydrogen with the help of bacteria in their guts.
The gut of all animals, and even humans, contains numerous bacteria. In many species, gut bacteria play a key role; for example, most plant-eating animals, such as hippos, are unable to digest one of the main constituents of plants, cellulose; gut bacteria in a compartmentalized stomach do it for them.
One of the products of the activity of some bacteria is flammable gas, such as methane and hydrogen, both of which can be produced by bacterial fermentation in the human colon. It has even been estimated that this process could lead to the use of bacteria on an industrial scale, to generate hydrogen for use as a fuel.
It is biologically conceivable then to assume that dragons had the ability to produce hydrogen and store it in a fuel storage unit similar to a bladder that trapped the hydrogen released, which would solve the fuel issue since hydrogen is a highly reactive fuel.
Oxygen is the easiest to supply, as it is in the air all around us. Assuming that these dragon-type animals inhaled roughly the same manner as other mammals—the debate about whether dragons would be a mammal or a reptile is a whole different matter, but the few dragon believing scientists lean towards dragons being mammals—the air that was drawn into the lungs was not totally depleted of oxygen when they exhaled.
In a normal healthy human, for instance, we inhale air with approximately 20.9% oxygen content, and then exhale air with about 15.3% oxygen content. Obviously the lung capacity of a dragon would affect how much oxygen this actually was, but it seems to me that this would be sufficient to coax a flame out of the body until it reaches the outside world, where external oxygen can then fulfill the need for further rapid oxidation.
The only thing left is the spark, the heat energy needed to start the reaction, chemically dubbed as the “Activation Energy”. We know hydrogen molecules violently react with oxygen when the existing molecular bonds break, and new bonds are formed between oxygen and hydrogen atoms. As the products of the reaction are at a lower energy level than the reactants, the result is an explosive release of energy and the production of water. However, hydrogen does not react with oxygen at room temperature; a source of energy is needed to ignite the mixture, a spark.
Introduction of a spark to the mixture results in raised temperatures amongst some of the hydrogen and oxygen molecules; molecules at higher temperatures travel faster and collide with more energy. If collision energies reach minimum activation energy sufficient to “break” the bonds between the reactants, then a reaction between hydrogen and oxygen follows. As hydrogen has low activation energy, only a small spark is needed to trigger a reaction with oxygen.
One could assume the dragon had an extraordinarily high internal body temperature, sufficient enough for a spark, but it would seem that such a feat would put these creatures at risk of constant spontaneous combustion; not the best survival strategy for a species.
Another option could be that they were able to strike a spark against their teeth. There is also the possibility of electricity; there are animals that create amounts of electricity—electric eels and electric rays—but none we know can generate a spark.
The most plausible solution, employed by the creators of Animal Planet’s documentary on dragons, is that dragons ingested platinum from rocks, and platinum acted as a catalyst that sparked the hydrogen oxygen reaction.
The scientific inspiration for the theory that dragons can ingest and grind platinum originates from many biological examples. For instance, birds do not have teeth, and many species rely on swallowing grit and even small stones to help grind up food in their gizzards. Dinosaur stomachs sometimes contained large stones, or gastroliths, worn smooth by grinding or exposure to digestive fluids; the stones probably also played a part in breaking down hard food. Modern crocodiles do much the same, the stones also serving as ballast for swimming.
Rather more special than these examples are the elephants of Mount Elgon in Kenya. Many animals congregate around salt licks; for the Mount Elgon elephants, though, the only natural source of salt is in deep caves in the sides of the mountain. Herds of elephants enter the caves, walk as far as 500 feet in pitch-darkness, then chip off chunks of salt-rich rock with their tusks and crunch them up.
The fact of the matter is that quite a number of animals take in minerals to use for their own purposes, why not dragons?
Combining all these theoretically feasible assumptions, we now have a dragon that produces hydrogen in its gut, combines it with oxygen in the presence of powdered platinum, previously ingested and grinded now serving as a catalyst; then poof, fire spews out of its jaws.
The final problem is how dragons avoided getting completely scorched by the fire it exhaled; one could assume that the inside of dragon’s mouth was armor-plated and that it had a false palate in its throat, similar to a crocodile, to stop back draft.
So, there you go; the possibility that fire-breathing dragons once existed is not so outrageous after all.
The Reality
One real living creature that comes close to possessing the ability of fire breathing is a little insect known as the Bombardier Beetle (Brachinus). This insect has evolved a little combustion chamber that combines several chemicals and can blast out hot gas, about 100ºC, from their rear end.
It is a remarkable defensive system; when threatened, it emits a rapid burst of scalding, irritating chemicals in the face of its attacker. The process is complex though; cells in the tip of the beetle's abdomen produce hydrogen peroxide (H2O2) and substances called hydroquinones, which are stored in a reservoir. This reservoir is connected to a thick-walled reaction chamber by a valve, controlled by a sphincter muscle.
The reaction chamber is lined with cells that secrete enzymes; when the reactive mixture of hydrogen peroxide and hydroquinones is passed into the reaction chamber, the enzymes break down the H2O2, releasing copious free oxygen, and catalyzing the oxidation of the hydroquinones.
The reaction generates enough heat to bring the volatile mixture to boiling point and vaporizes much of it, which greatly increases the pressure within the reaction vessel, forcing the valve shut, preventing backfires, and expelling the mixture explosively through openings in the tip of the abdomen.
Although the scalding chemicals produced by the beetle are in no way as hot as fire—the coldest visible fire is at least 525°C—but it is pretty hot, and the closest living example to fire breathing. After all, it is just a tiny beetle; one would not expect it to produce a firestorm!
So, what do you think? Could dragons have been real? Maybe if you believe in them, that is real enough.
References
http://www.livescience.com
http://animal.discovery.com
http://www.ehow.com