I, as a former humanities major, should really not be trying to puzzle out ghoul evolution, but here goes -
Realistically, we are looking at a subspecies of homo sapiens here. If there is argument as to whether to classify Neanderthal as a subspecies or not, there is no question that ghouls are, or at least should be, Homo sapiens [ghoul].
At some point, they diverged as a separate species. Might still be diverging, from an evolutionary point of view.
Ishida doesn’t really give us much in terms of history outside of Japan, or even the international ghoul scene, but one of the big clues on when ghouls developed would have been whether or not they existed in pre-Colombian America or not.
It’s fun to speculate, given all the cannibalism-taboo based creatures in Native American myth, but lets be fair, those exist in our ghoul-free world. But assuming the pre-Colombian Americans had ghouls, and the ghouls native to the Americas are biologically similar to the ghouls we know - i.e. breed true with other ghouls, produce half-humans or rarely one-eyes with humans, and have similar species markers - then we at least have a time frame for probable species divergence, as it is possible but unlikely that two groups of isolated proto-ghouls would diverge from humans in the exact same way - i.e. the group in the America and the group elsewhere.
So assuming we are looking at species divergence finishing by around 20,000 years ago, what is the earliest possible date.
Now, again, we’ve only seen Japan here, but in Japan at least, we know ghouls are visibly indistinguishable from the general population. Weird manga-world hair colors aside, Japanese people still look Japanese in this world. Meaning Japanese ghouls look Japanese. Russian ghouls, like Donato, probably don’t look Japanese. Meaning that Ghouls around the world seem to have the racial characteristics of the native population.
Meaning that during the evolutionary period when such characteristics were forming, Ghouls and humans could likely still interbreed, but were still more or less distinct species. I say this, with my very limited knowledge of biology and speciation, because ghouls around the world seem to all be the same species while all looking like the local human population. Humans achieve this because they all came from one location - from Africa around 50,000 years ago.
Were their already ghouls in their group at the time? There must have been, unless there are parts of the world which did not natively have ghouls and ghouls only traveled to later. Given our lack of information, this is certainly possible. It’s possible that ghouls first evolved during a human migration out of Africa in the Middle East and that there weren’t any ghouls in Africa until later when people started moving around.
But what I’m proposing is that in that group of humans that left Africa were the Adam and Eve of what are the ghouls of today, so to speak. And the ghouls that travelled with this migration must have been sufficiently distinct from humans that even if they could still interbreed, maybe only successfully on occasion, they maintained enough of a separate species distinction that their ghoulish offspring were the same species no matter if they were part of the group that headed up to Scandinavia or out towards the Indian subcontinent.
I would posit that the species divergence must have happened all the way back there, but interbreeding has gotten harder over time, somehow. And this is where my lack of science education fails me. If, back 50,000 years ago, every hundred or so times a human and a ghoul produced a viable, fertile ghoul child, then perhaps it would be enough to keep the ghoul population. I don’t know how it would work.
But somehow they would have had to both maintain their species and evolve racial characteristics in parallel with the humans around them.
I suppose it could have just been parallel selective pressures plus the fact that there was the additional selective pressure of being hunted down if you didn’t blend in. But I don’t know if that would be enough, given that evolution is so undirected. I think crossbreeding would be necessary.
Which is all not even to get into the numbers of it. How many ghouls would there have to be per human population to sustain both populations and allow sufficient genetic diversity of the ghoul population? And allow for ghouls to have remained the oppressed and subjugated monsters throughout history?
Ecologically speaking, prey animals outnumber predator animals, but humans like to upset and mess with that rule wherever they go, what with domestication and farming and stuff. Ghouls don’t seem to do that, despite the intelligence. What would the numbers even look like. I guess I’m pushing this into sociology or anthropology, huh?
I dunno. I majored in humanities. I’m supposed to be writing about existentialism and literary foils, not evolution.
It’s possible that ghouls evolved a lot later and just spread around the world, and all ghouls look vaguely Japanese, for all we know.
I cede the floor to someone who knows more about this than I do. @silverbulletsama? anyone? wanna take this post away from me? Touka? Nishiki?
Ron:No, I mean Wizard Pictionary. It's like pictionary, but you act it out with your body! Because wizard pictures move! I keep forgetting you were raised by Muggles, Hermione. Seriously, you missed out on so much.
Hermione:That is definitely charades. And we had electricity.
Ron:I bet you never even had Wizard Pies. They're these flat little pastries that you put on your fireplace, and when they're done heating up, they fly up out of the fireplace and into your hand. Then you get a second-degree burn. Classic wizard kid breakfast! I'm getting all nostalgic just thinking about it.
Hermione:That is literally just a worse version of a Pop-Tart.
More ghoul/half-ghoul/half-human biology because I don’t know how to stay in my lane.
Humans produce RC cells, somewhere between 150-500 count. We don’t know if they used them or what, but they produce them pretty regularly.
Ghouls do not produce RC cells, but they have a kakuhou which allows them to store RC cells from the meat they eat, and thus they generally have an RC count of over 1000.
RC gates work by detecting the RC level in an individual that walks through them.
RC gates would, if not for being coded explicitly to avoid doing so, go off for the half-human Garden children.
Meaning that either the Garden children are producing RC cells at a rate much higher than a normal human (and certainly higher than any ghoul, who have a rate of 0) or they have some sort of kakuhou or kakuhou equivalent.
Arima specifically mentions a kagune, not a kakuhou.
I wonder if this is in any way analogous to the Qs system, another project Yoshitoki was invested in, that creates a human with an elevated RC count who can still eat human food.
But it is interesting that whatever program Marude is looking at, he seems to see it as reacted to Hsiao, but not the other Quinx, and more interestingly, not Sasaki. Sasaki, who the CCG probably had to tell the RC gate to ignore, which Marude would have accepted because everyone knows he’s a half ghoul - but who would also ping this program because he has Rize’s kagune - which we know is still in the system because Furuta doesn’t set it off.
(as for why he doesn’t mention Furuta, I kind of assume that, having known Chika when he looked basically exactly like Furuta, Marude has long since cornered Yoshitoki about the investigator who looks just like him and surmised or at least suspected that Furuta is a Washuu bastard. If he didn’t suspect if before, I’m sure paying close attention to them would have led him to peak at the young Yoshitoki look alike. idk. I just kind of assume Marude is counting him in the “Washuu Clan.” Maru is a smart guy.)
For Sasaki, that can be answered with a dumb technicality that the public program to ignore him activates first and thus prevents the second one from even registering him. For the Quinx it could be that Hsiao, as a Garden Child, has an RC count that would register while none of the Quinx do. Or, because the Gate programmer is weird, the program that tells the gate to ignore the Qs runs after the program to tell it to ignore the Garden kids and the answer is just arbitrary code ordering.
Or the gate wouldn’t ping the other Qs either way (which, temporary good news for Urie, I guess) and Maru doesn’t mention Sasaki because that isn’t relevant to this, Yoshitoki, he isn’t hiding it.
It’s almost enough to make me wonder about whether or not Hsiao is actually a Quinx or if there is something else going on with her (a random kid shipped over from Taiwan? Do they have another lab there or did V just track down a kid born naturally to a ghoul and a human?) but she does seem to have the same grey kakugan as the rest of the Qs, which probably wouldn’t be the case if she were using her own kagune.
Still, it does seem that all the half-human children must have some sort of RC storage organ for the gate to sense them.
I don’t know if or how this contributes to their shortened life spans or premature degrading or what, or how this syncs up with any theories on ghoul biology, but there you go.
Wanna wait to edit my “kagune are magic” post because while Tatara generating fire, let alone doing so right next to his face holes, is bullshit enough, the claim that it is around 4000c really takes the cake. That is a temperature hot enough to sublimate (i.e. vaporize) diamond, a super non-reactive, stable substance.
So I wanna see that one in print before really throwing in the towel.
The Yomo family lightning is slightly less absurd because lightning, while hotter, isn’t a sustained temperature, and it isn’t the lightning itself that is that temperature - its the air/plasma around it that’s superheated by the sudden surge of electric current. And our bodies already have electricity in them. The Yomo family lightning is a discharge of a build up electric current, not holding a steady stream of 4000 degrees celsius next to your goddamn face.
What is this, a pokedex entry?
But even if it’s not 4000c it’s still kind of absurd. Long term exposure to high temperature is really devastates to the human body. We are meat after all. And, as Touka so elegantly spat at Tsukiyama, even a ghoul can be eaten.
So if Kaneki could eat Eto’s kakuja, it’s just kind of absurd that Tatara can do this with fire.
Fire requires fuel. What is he burning? Fire breathers are constantly spitting out a flow of some sort of highly flammable liquid (with a practice and skill that keeps the flame from jumping back through into their mouths, which can and has killed people). You can’t actually burn anger…
Is he burning RC cells? Can he turn RC cells into a fat or an oil and burn that? How long can he sustain that kind of waste of RC cells? And how is he protecting the rest of his body/kakuja? Even with monster regeneration, burning damage is some of the most damaging and hardest to heal from and most likely to cause your body to just straight shut down from shock.
Or are we supposed to just… give up on thinking critically about kagune because they are just magic now…