EPT
We here at the N3rd Dimension are big fans of cartoons. With the unfortunate and untimely demise of one of the best cartoons on television, we've all mourned in our own ways. Mine is to look back at some of the other all-time greats, immersing myself in the-good-that-once-was-airing, since even the best of them have completed their runs. In this time of great difficulty and struggle, I've been re-watching some of the Avatar series, both The Last Airbender and The Legend of Korra, two (relatively) recent cartoon triumphs in the same league (haha) as our dearly departed Young Justice.
As usual, watching a few episodes got me thinking, this time specifically about the show's central fantasy element: bending. Most children's cartoons, when introducing the fantastical concept around which the show is based, simply state its magical nature and never focus on it again. One especially egregious example would be One Piece, where it's explained that the Demon Fruits give magical powers, but neither how nor why.* The Avatar series, on the other hand, goes into more depth than most shows about how the powers work, describing some of the physical mechanics behind the four (five) bending disciplines. From these simple explanations, one can make some logical conclusions about the biological aspects of the bending abilities, further elucidating the fantasic elements of the show.
* It may be the case that this is the least ridiculous thing about One Piece, but still.
Notably, I'm neither a writer for the Avatar series (WOULD THAT I WERE) nor someone with any medical or biological knowledge, but that's never stopped me before. In spite of this, I think that some solid hypotheses can be constructed about the Avatar universe and its phenomenal element-wielding characters. We can guess at quite a bit of the biology of benders far before anyone in the series invents the microscope or X-ray.
Oh, and if you haven't seen the shows, there are spoilers ahead. You have been warned.
As many characters in the show will tell you, the foundation of bending is Chi, known to the people of the Four Nations as an energy which travels within the human body. In particular, it is the flow of Chi through the body which enables the bending arts. Yet it seems more plausible that Chi is not a mystical force, but a bodily fluid, much like blood. Like blood, Chi is most likely present in all humans, even non-benders. As demonstrated by the Water Tribe healers in the North Pole, there are Chi "pathways" throughout the body, much like veins. As healing seems to be a technique centered around Chi and its movement, we can assume that Chi is present in all beings because they can be healed. We also know that bending techniques require physical action in the form of various katas; without them, bending is nearly impossible, save for by the masterful or extraordinarily talented. In fact, there is a distinct pattern between movement and bending abilities, which indicates that moving has a specific, reproducible, and physical effect on Chi. It seems far more likely that these actions spur liquid into motion rather than "push" a kind of energy. Thus, we can surmise that Chi is an inert liquid in the human body, and that it requires movement (either via bending forms or healing) to effect the environment, as through bending. The difference between benders and non-benders, then, is the relative inertia of their Chi. Non-benders have a Chi that is nearly impossible to move, preventing them from practicing the bending arts.
Similarly, the idea that Chi is a bodily fluid explains the external influence that can be levied upon it by warriors such as Chi-blockers. We know that the body has Chi-veins and that these pathways can be temporarily blocked by precision strikes, inhibiting all bending (and conferring a case of the noodle arms). If Chi is a bodily fluid, then Chi-blocking fighters are targeting the veins through which the Chi flows, rather than an intangible energy (which seems like it would be as difficult to "hit" as it would be to physically move). This also clarifies Amon's unique ability to deprive benders of their bending abilities. As an immensely talented waterbender and bloodbender, it is likely that Amon was the only human that understood the fluidic nature of Chi, it likely being (like most things in the human body) partially water. If his senses, finely attuned by his bloodbending training, were able to sense the flow of liquid Chi, then he may have been able to find a way to permanently close the Chi paths or even increase the viscosity of the liquid itself, rending a non-bending life unto a bender.
If Chi is a universal human trait, what then created the unique bending talents of the Four Nations? The benders of each nation claim that their bending disciplines were "taught" to them by a force of nature, whether animal or environmental: the dragons, the badgermoles, the skybisons, or the Moon. However, it is much more likely that the first benders observed the instinctual actions of these creatures (who also possess Chi) and began to act similarly, unlocking their own already-extant bending potential while simultaneously creating the first bending forms. Furthermore, the environmental conditions of each Nation likely caused specific mutations in the development of the Chi-veins, resulting in each region possessing a different bending discipline. How each mutation might have occurred is unclear, but the genetics of Chi explain both the hereditary nature of bending (why are all Air Nomads airbenders? LOTS of inbreeding) as well as the regional bias towards the bending disciplines. It also explains the existence of unique benders (such as Amon or Combustion Man) as those who have special Chi-vein mutations, producing new and terrifying strengths. Since benders in Korra's time no longer keep exclusively to their Nations, there is potential for the eventual cross-breeding of Chi-related traits. This could possibly lead to new bending mutations, including multi-elemental benders.
Speaking of multi-elemental benders, how do these ideas about Chi and the biologial aspects of bending affect the titular Avatars? Let's note here that with the Avatar, things start getting far more mystical and weird, deviating from the "scientific" path I've attempted to establish. The Avatar is a unique and persistent bending mutation, conferring to one human four sets of Chi-veins, one of each of those typically exclusive to the Four Nations, as well as enough Chi to utilize all four sets. Having all of the Chi-veins allows the Avatar to bend all four elements, though learning the subtle movements to activate one Chi flow instead of another is a daunting task (as shown by the many years of Avatar training, and particularly in the struggles certain Avatars have with certain elements). Notably, since in the Avatar four sets of Chi-veins occupy the same space usually reserved for one set, they cannot be as large or as extensive, illustrating why the Avatar is not able to use the advanced techniques inherent to those with especially advanced Chi-veins of one element: lightning, metalbending, and bloodbending. The massive amounts of Chi itself has other effects on the body of the Avatar, including the ability to contact and interact with the Spirit World and the power to enter the Avatar State.
At this point, we have to relinquish slighty to the mystical nature of Chi or this theory falls apart. While it is a bodily fluid (and acts as such nearly all of the time), Chi is still a mystical substance (it does allow people to create FIRE after all). Though the amount of Chi in the normal human body only carries the strength to enable bending, it is far more powerful in greater quanities. In fact, in large amounts, Chi takes on supernatural properties. The Avatar's massive amount of Chi is one example of this, as it seems to be both semi-sentient and immortal, traits which can be observed in the powers of the Avatar and the cycle of reincarnation. Upon the Avatar's death, the Chi of the Avatar moves to a new host, one that either already possesses the four-Chi-vein mutation (implying that the mutation is far more common than the ability to take advantage of it) or one whose development can still be altered, in whom the Chi itself creates the mutation that allows it to be utilized. The existence of an aware and persistent Avatar-Chi explains why the Cycle of the Elements is followed and why the ancestral memory ("past lives") of the Avatar is carried from host to host: the Avatar-Chi lifeform remembers. The Avatar State, then, is an increased level of communication or bonding between the Avatar-Chi and its current host, enabling the signature massive power spike. In this state, the Avatar-Chi floods all of the Chi-veins at once, causing the simultaneous bending, the glowing (the effect of tremendous amounts of Chi cascading through the body), and the occasional loss of control (since, until you've mastered the Avatar-Chi, you're essentially being possessed by an alien entity). Finally, the Avatar-Chi enables the connection to the Spirit World, a realm made solely of Chi and populated by Chi-based lifeforms. If this is the case, then the Avatar, bonded with an immortal Chi-lifeform, is truly the bridge between the real world and the Spirit World.
Armed with this knowledge, we come to the scene that helped me create this theory: when Amon blocks Korra's earth, fire, and waterbending, causing her to finally access her airbending abilities. Until that moment, Korra, who demonstrated proficiency with the first three bending styles at an early age, had been unable to airbend. She had also been unable to enter the Avatar State or contact any of her previous lives in a significant way (only through a few meditative sessions in which she reached Aang's memories). During the battle, Amon finally overcomes Korra using his bloodbending and attempts to remove her bending talents. However, this tactic relies upon Amon sensing the flow of liquid Chi. Because Korra had dormant Chi in her Air-Chi-Veins (if you will), Amon was only able to sense the flow of Chi in the veins of the other elements, which he closed. Amon was probably not prepared for the difference between an Avatar's and a regular human's physiology, so he likely closed off the flow of Chi as he always had, not noticing that there were three distinct active streams and one inactive stream. In a standard bender with a normal amount of Chi, this technique leaves the Chi-veins irrevocably damaged and the Chi with nowhere else to go. Korra, on the other hand, is endowed with the monumental Avatar-Chi, as well as four separate networks of Chi-veins, including one that Amon had not blocked. Much in the way that feats of strength can be performed at harrowing times, seeing Mako in danger allowed Korra to instinctively redirect the huge inactive flow of Chi into her Air-Chi-Veins (possibly through the Air Chakra... which I could cover if this weren't already long enough), allowing her to finally airbend.
After Amon is defeated, Korra still can only bend one element, though doing so is probably far easier because of simple sense memory, not to mention the still-extant floods of Chi. In her misery, she finally makes contact with the Avatar-Chi, allowing her not just to receive advice from her predecessor, but also to enter the Avatar State. As we saw when Aang apprehended Yakone, the Avatar State's flood of Chi allows for the Avatar to regain control of the body through his/her wide network of Chi-veins, rendering bloodbending ineffective; the body's water is still under the control of the bloodbender, but the torrents of Avatar-Chi are a stronger and more direct form of control (again, mystical). When Korra enters the Avatar State, the Avatar-Chi floods through her Chi-veins, undoing the damage rendered by Amon. Finally, the Avatar State experience gives Korra the ability to use "energybending," a form of bending given to Aang by a Lion Turtle which allows the user to manipulate Chi itself. Unlike the other forms of bending, in which the body is manipulated to move the Chi in a way that activates bending abilities, energybending bends Chi itself. So while Amon's bloodbending technique acted on the Chi veins and fluid (the water-like aspects of Chi), energybending controls the properties of Chi, including its activity. During his time, Aang used the technique to "deaden" the Chi activity of both Ozai and Yakone, permanently removing their bending unless it were restored by another true energybender. On the other hand, Korra's energybending was able to override Amon's bloodbending blocks by reverting the Chi to its unaltered, free-flowing state. This procedure was first used on Lin Beifong, then, assumedly, the rest of the benders crippled by Amon.
So there you have it. An (obsessively) thought-out, (needlessly) comprehensive, (exhaustively) extensive review/theory/hypothesis of the physiology of bending and the Chi that fuels it all. In the end, this all stems back to the fact that Avatar is well-written enough that these speculations can be made off of in-show evidence, rather than pure creativity (though that helps). Hopefully, when the theories of Avatar are exhausted, there will be another wonderful cartoon that can be discussed in such detail.
Oh, and if you made it all the way down here YOU ARE A FUCKING CHAMPION.
You can read this obsessively long post and many more (though most are shorter) at the N3rd Dimension.
