Headscratchers / Dr. STONE

New entries on the bottom.

Astronauts and revival fluid

• Why didn't the astronauts try to reverse the petrification? Why didn't they set up base in the city? Then they wouldn't have died so easily or left their children with nothing but stone-age technology and a collection of stories. Instead, they assume Senku is alive and will wake up one day to fix everything.
  • Maybe they didn't know it'd work. That's my theory. Some people in real life don't think they'll succeed, even if they have all the means to do so.
  • Maybe they did, but simply didn't come across the nitric acid solution.
  • Loads of reason. Fear of finding out they are all really dead in the stone, fear of breaking the stone, fear of killing themselves creating it. Abandoned on a nonmainland island means they did no have spare chemicals at their disposal and would have had a limited amount to run tests on while doing what they can to survive.
  • And most damning of all? It's a solution. Meaning if you don't use the right chemicals to the right amount you aren't getting the right finished product.
  • They wound up trapped on an island hundreds of miles from Japan that had been inhabited by one single man with one small boat. If they had landed on the mainland it would have been trivial. Byakuya had to make the First Story one that would lead their descendants to get to Japan once they figured out shipbuilding. Waiting for Senku wasn't plan A, it was a last-ditch plan E.

Inbreeding

• If there were only the 6 astronauts that came back to earth, how inbred are their descendants over 3,700 years?
  • Inbreeding only causes a real problem within 3 or 4 generations, after that, the gene pool is distilled enough to not get the problems that go with incest. Assuming they all had at least 4 children, it's possible to get up to 4 generations with no inbreeding.
  • That's not how inbreeding works though. It's not about the generations, it's about genetic diversity. The genes of everyone in the village are all based on different combinations of the same 6 original sets of DNA. Genetically speaking they are all siblings no matter how many generations apart. Realistically these people should have all died/gone sterile from genetic defects after at most 20 generations.
  • It could be possible that over the course of the years, some of the humans trapped in stone managed to break out which would put some ease on the genetic diversity, but there are still a few problems with this; not the least of which being there was only one seen statue on the island that the astronauts live on.
  • They are dealt an excellent hand though as five out of the six founders are career astronauts, hence likely to be much healthier than the average person. Also, the initial gene pool has enough internal diversity, as two out of the six are Asian (Byakuya the Japanese, and Connie the Chinese American.) If they have fewer genetic defects, to begin with, it would take longer for those defective genes to accumulate and show up on someone.
  • Given the time, 3700 years, the current population is at least 150 generations from the founders'. This is enough generations for genetic mutations and natural selection to start kicking in and diversify the population again.
  • And once Senku and other depetrified humans arrive, this village would gain a boost of genetic diversity and resolve this problem once and for all. With a few exceptions like Taiju/Yuzuriha and Chrome/Ruri, it is likely that those people would mix when coming to reproduction. (I personally stand Senku/Kohaku, for example.)
  • People keep pointing to "6 Astronauts" being the village founders, but there's no actual indication Lilian and Byakuya had kids. We only see 4 kids forming the next generation after the astronauts, and these kids are 2 pairs of siblings. Lilian seems to die young in the flashback, with only said four kids existing. The entire village is descended from 2 pairs of siblings.
  • Lilian and Byakuya had kids. In addition to everyone being descended from two pairs instead of three being even less probable, the village is described as being descended from Byakuya, and Kohaku and Ruri look exactly like Lilian.

Hating adults

• Tsukasa hates adults and wants to rid the world of them all. So what does he intend to do when he grows into an adult?
  • He doesn't "hate adults", he hates the greed and corruption of the adults in the old world. His plan was to explicitly free people who would not be like that.
  • Also, he's the Bad Guy. Having his logic be flawed is kinda part of the deal.
  • And continuing in the 'flawed logic' vein, Tsukasa claimed that there wasn't enough food to feed all of the humans in the 'old world', and that the earth couldn't support that high of a population... which is completely wrong, as there is NO SHORTAGE of food in the modern world, period. The problem isn't lack of food, it's that the food available isn't GETTING TO the people who need it, due to concerns of logistics, greed, etc. Which would support his own anti-corrupt-old-people argument FAR more than what he actually says.
  • Despite what is said about his smarts by other characters, Tsukasa isn't much of a thinker beyond the immediate moment. He's impulsive and violent, and his whole Caveman Conan thing leads itself more to someone who never interrogates his own beliefs than to anyone who reasons out or examines why people would disagree.

Gravestone

• The record that Byakuya and the others left behind was supposedly the founders grave. However, they would have been buried on the island. In other words, one of Ishigami villages' founders would have had to have taken a very important gravestone on a journey that they had no way of knowing they would come back from, and risk losing it forever. Why didn't they just leave it on the island where it would be safe, other than the fact that the plot had to happen?
  • Ishigami villagers are too the descendants of the original six. When the initial population on the island decided to migrate to Japan proper following the stories, folks that uprooted themselves, whose descendants are now Ishigami Village, are the primary team and took the gravestones with them; while folks left behind are the backup team.

Technology in the village

• Why isn't there more technology at the village? It's been over 3000 years, yet, they're both an incredibly small village, and they don't even have things like the water wheel. That's not even going into the fact that their founders knew about tech. Maybe not to the extreme degree as Senku, but they left behind 100 stories, why not ideas like Cogs, Pulleys, or even Billows for a furnace?
  • Perhaps they did, but there could have been a number of reasons for abandoning or reverting progress such as Luddites, tragedies and disasters. The village also seems to be distrustful of advancements and labeling it sorcery.
  • Alchemists were a thing though historically, and it was a relatively respected profession, often overlapping with Doctors. In fact, now that I think about it, where the hell is the village doctor?
  • Sorcery in the Stone World basically is what Alchemy would've been when it was new, albeit it is viewed in a different light. As for who the doctor of the village is, that would probably most likely be Jasper going by his position in the village, although we can't know for certain since there's no confirmation. Chrome also counts (technically) as he studies herbs and their effects for medicinal purposes. But again, he's labeled as dabbling in sorcery.
  • That's my point, why is it "New"? 3000's years have passed, more than that, 3000 years, wherein the initial decades after the tragedy, they'd know about all the tech and science, at least as ideas. In 3000 years, with the ideas of the past at least partially alive in their stories, they don't have Water Wheels? They don't have cogs? Or, as a more cultural item, no Katanas? Steam Engines, for instance, would be relatively simple to make and could be adapted to work for carts and boats. I'm not saying that it would be the most efficient thing ever, but it would exist. As it is, after 3000 years, Senku needs to teach them "Everything" again. Including things that they should have known about for years, such as Glassmaking.
  • Technological innovation mostly occurs in two situations: 1) When there's a pressing need for it, aka new weapons in times of war, new medicines when there are plagues going around, etc, and 2) When there's enough free time for people to do whatever they want. That implies there is enough people for labor to not be an issue, and for there to be a stable food supply and living situation so that everyone's time isn't dedicated to survival. Considering Ishigami Village isn't even 100 people, I doubt you'd get very much scientific progress of any sort going. I'm amazed that someone like Chrome even managed to pop up, considering that they probably should have been forcing him to fish or farm or gather or whatever rather than faffing about with rocks.
  • So, they should have more technology then, as they were pressing needs for it. Aka, things like Ruri's pneumonia, which was something that affected even the astronauts, so that should have been something of a priority. And combine that with how the Astronauts could have told them of so many different concepts, like machines, steam power, etc. And as evidenced by the 100 stories, they can keep at least the ideas going for a long time, so they should have something to show for it. But, they really don't. Now, to make it clear, I can understand them not having some technology, but my issue with their lack of technology is the appearance of how "complete" it is.
  • This is likely due to the modern usage of technology bringing to mind significant current advancements in the field when really it can mean any tools and techniques which are used to progress civilization forward. Everything you see that was built by the villagers, including the implied techniques used to build them, is effectively their technology showcase. Also in regards to Ruri's pneumonia being a priority, that's exactly what Chrome was doing; he was self-applying herbs and noting their medicinal applicability, which is about as basic as developing medicine gets. There's no way they're going to get to advancements like Senku can (or even over the course of 3,700 years, for that matter) because they had to start from scratch.
  • That's been my point though, they didn't start from scratch. Or rather, they shouldn't have at least. They had the Astronauts to instill ideas into everything. Keep in mind that the villagers kept the 100 stories alive over 3000 years, but the astronauts never told anyone about gears? About jarring food, about glass, about stoves, and so on. Mind you, the Astronauts were able to make a recorder to create that record, but they didn't create "Anything" else? I recall that Senku making gears and pullies was something seen as groundbreaking, which should have been something that the astronauts would have known about easily. Like I said before, I can understand them not having a bunch of technology, but the near-complete lack of technology bugs me.
  • As far as that goes, it's most likely because most of the Astronauts intended on reviving everyone instead of letting themselves become ground zero for a new human civilization, thus they didn't see a need to pass on those teachings before a quick pneumonia strike did them in. Also keep in mind that most of the children were toddlers or babies when 2 of the couples shortly perished, leaving Byakuya and Lillian left to teach them when they were at an older age. Byakuya was the only person in the group who really decided to look towards the possibility of them never finding a solution, and making and suggesting things such as the one hundred tales and the record, knowing that Senku may someday break out of the stone and make good use of them.
  • But, that's just it, I'm not saying they needed to recreate the technology themselves, but if they could pass on the 100 stories, while not the "Ideas" of some other basic tools? I'm not saying that the astronauts needed to remake everything, but they should have given ideas on how to do stuff to their kids and grandkids. Maybe incorporate them into the 100 stories. Then, generation after generation, they'd have the ideas for the inventions, to work on and slowly invent, with the headstart of having the basic idea of the invention already made and instilled into the stories.
  • Firstly, you have to remember that the astronauts, while experts in their fields, did not have the kind of all-encompassing encyclopedic knowlege that Senku has. Secondly, a main point of the series is the layers and layers of technology that support every other piece. To take an example; producing a steam engine requires not only access to raw materials, but manpower to extract and refine the iron AND knowlege. Raw materials are already problematic. The Japanese archipelago is notoriously lacking in iron deposits, and the iron sand used to make tamahagane, a crucible steel, is loaded with impurities that are time consuming and labor-intensive to work out by hand. Gathering iron sands is less labor-intensive than mining hematite ore, but it's an activity that a subsistence population couldn't afford. As for knowlege, the metallurgy and mathematics involved in creating a pressure chamber for a steam engine is complicated, and IIRC, none of the astronauts was a metallurgist.
  • I understand and acknowledge that. But... the complete lack of everything is my issue. You can make a primitive stove out of Mud and Stone. If they can find Clay, even better. But, that's not even my point. Even if the astronauts didn't know how to make this stuff, they knew of them as concepts, ideas, and so on. Why not pass them on? 100 stories were passed on, for over 3000 years. So why not stuff like stoves? Like Glass? Explain stuff that can help, while also explaining that they'd need to figure out a lot of it themselves. Sure, the astronauts may not have the metallurgist skill for the steam engine, but that could have been something built up in the past 3000 years.
  • You’re making a big assumption that the village’s population and knowledge base is continuously increasing over 3000 years. The pneumonia epidemic isn’t considered ‘a curse from the gods’ or anything of the like, so that’s an implication that the village has seen outbreaks before. A major culling, or dozens, throughout those thousands of years could easily reset their tech base as minds that could’ve normally researched and developed had to absolutely focus on just survival. The eventual mass inbreeding would have also made the population more vulnerable to disease, since their immune systems would lack diversity.
  • Survival, like indoor heating/stoves? You can make primative indoor stoves with mud alone, yet Senku's stove seems to be their first exposure to it. Pulley's, Cogs, Water-wheels, all relatively simple in terms of concepts, and creation. Inventions that would have been widely used/maintained due to how useful they would be, towards survival. Metal working would be huge, and that's pretty basic as well. Mastery of it is hard, but just understanding the concept of "Find special rocks, melt them in a super hot fire, and mold into a new shape" isn't something that would be hard to convey. Especially when one considers that 100 stories were able to be passed on this whole time with little to no changes whatsoever. One can make literal Mud Bricks, and use them in construction, which would have been huge. Things that are important for survival, that are simple enough that they should be widespread within the village, but aren't. These are things that the Astronauts could have made, or at least taught to their children. It would be nigh impossible to destroy something like that, while also managing to actually stay alive.
    • First, you’re working backwards with the concepts already in mind; a number of cultures were missing technologies we’d consider ubiquitous, or at least never used them to any meaningful degrees, and they were from a stabilized population. Second, it’s established that Ishigami Village is somewhat backwards, branding Chrome and Senku’s tricks as sorcery despite all of them being easily observable and capable of being replicated. Trying to convince them to put resources, manpower, and time towards research is a tall order already. For all we know, Ishigami Village may have had stoves, water wheels, and katanas 1000 years ago, someone got killed in an accident, and a Magma-analogue took power to destroy the nasty, new technology. Third, Ishigami Village seems to keep most of their cultural and scientific knowledge to an elite class (Ruri’s vaguely described as a priestess). Plenty of cultures have been ruined by their scholars holding the entirety of their social/scientific/cultural progress and then dying before passing it on. The astronauts themselves didn’t plan on reestablishing civilization from step 0 until much later, and then died fast from pneumonia, leaving only Byakuya and Lilian (who, while intelligent, did not have the knowledge needed). Fourth, you are severely underestimating how screwed Japan is in terms of metal deposits. Mining for fancy rocks would be a rough ordeal (using up time and energy better put towards finding food and water), and then you’d have to refine it (so more time and energy) to get a metal more useful than wood or stone. Fifth, when we’re talking about survival, it’s more ‘using every drop of energy to last one more day’ levels. Only the villagers would be suffering from poor health (due to not having a nanotech hotfix) disease (remember inbreeding = easier disease), and guys like Magma threatening to cave their heads in if they deviate even slightly from the status quo. Senku got really lucky waking up when the Village had a decent population, and Chrome as a willing assistant (and his stock of resources).
    • I will fully admit to working backwards, as that was part of the premise. 100 Stories were passed down, near perfectly as far as it's been revealed. Why not include elements of technology into that? Like, Ignoring metal working at all, mud stoves are possible, which can also lead to primitive mud bricks. Clay would be better, but still, you're telling me Mud tech would be too advanced? We even know they've got pots, meaning that Pottery was passed down/reinvented. Pulley's should be in use to help move stuff, or help with their boat's rigging. I'm not saying that the tech should be anywhere close to modern day, or even medieval, I'm more wondering about the almost "complete" lack of tech. They could even still label it magic and sorcery, it could be random what's survived and what's hasn't, but the complete lack is what confuses me.
  • They do have technology. They have boats. Ishigami village is an island village, descended from people who split off from the original Treasure Island village and sailed to Japan. As result, the only technology that stuck around and evolved was nautical technology since it was the most relevant to their way of life. So much so, that even the village meathead, Magma, is able to whip up some respectable schematics that 10 billion percent puts modern-man, 21st century Yo's shoddy excuse for a raft to shame.
    • They don't have nautical technology though, at least, not much more then boats. Pulleys are something new to them, when pulleys are incredibly useful on boats. Gears, are also new inventions to them, which, again, are incredibly useful to boats, or fishing. Both are also relatively simple concepts. And the point of this was never to say they didn't have any technology, but that the near complete lack of it was weird, especially when combined with the 100 stories. Ideas for the technology should have been embedded into some stories, just like with the "Speaker Bee", but less changed.
    • On the contrary, boats themselves are still technology, and though the Ishigami residents may not have understood the complete science of it at the time, they still had knowledge of how to build a seaworthy craft. The outrigger boat plans Magma proposed (chapter 84) is a two hulled craft that offers stability from the distance of the two hulls rather than the broadness of a single hull. This would offer more hydrodynamics since the hulls can afford to be narrower than single hulled ships, thus cleaving through the water easier. There's even historical precedence for this type of boat traversing the ocean as it was the type of boat the Austronesian people used to sail the Pacific and go on to populate the Polynesian Triangle (this is where indigenous Hawaiians came from). It's so good that the outrigger design is still used to this day. A stark contrast from the reed canoe that Amaryllis and her group used in their attempted escape from Treasure Island (chapter 106), an island that got taken over with brigands wielding petrifying weapons and prohibited the advancement of technology and forbade anyone from escaping.
    • I know, notice how the first things I mentioned were the boats as the exception? My point is more, even with the focus on boats, they haven't really advanced all that much. The point of this was never any specific style or branch of technology, nor even any specific piece of technology. Just that, with the 100 stories based down, as far as been shown, nigh perfectly, are they so behind? We know that some things were left behind, like the "Speaker Bee" so why not a more serious story about other tech, like gears, or pulleys, or bricks, or even glass. I understand not all of those would have been developed, but there should have been something there.

Eternal Japanese

• How the heck is Senku (and anybody else from the modern era) able to understand the villagers? Some degree of the linguistic shift should be taking place over time. English from just 800 years ago is barely comprehensible to a modern speaker, never mind 3700 years. Even if the village is small, there's no way language wouldn't change over time, especially as since the villagers are all descended from the astronauts, their language would be a mishmash of English, Japanese, and Russian. Not even a genius like Senku would be able to communicate fluently.
  • This bothered me as well. In fact, it bothered me as soon as the villagers were introduced. Senku's first thought should have been "Why do they speak Japanese?" It wouldn't really bother me that much in other shows but this one strives to have some form of realism despite the fantasy premise. It also later directly references the fact that they're speaking Japanese when Senku's dad talks about how he has a hard time writing the 100 stories in English. The whole Astronaut plot really took me out of the show. Senku's initial assumption that there'd been a prior awakening makes way more sense.
  • We have Senku's dad to thank for that. He created the 100 stories in Japanese and instructed their descendants to pass them down verbatim. When a language is tied to a piece of literature that is passed down verbatim for millennia, that language becomes eternal. We even have a Real Life example in formal Arabic, which is eternal thanks to being tied to the Quran.
  • Arabic isn't an eternal language. It's evolved less than most, but there's still tonnes of different dialects out there. And given another three thousand years (which is a hell of a long time) it will continue to evolve further.
  • The isolation could be the answer. Languages change when their users encounter other languages and concepts that they were not aware of before. A completely isolated community like the Ishigami village would not encounter any outside influences, making it harder for their language to change in any considerable way.

Empire of Might and disease

• What exactly would Tsukasa have done if his little empire had been hit with pneumonia, like Ruri was? Or someone had appendicitis, or any other numerous diseases and things that can go wrong with the human body? With no science and no medicine, they would be decimated. You'd think Tsukasa would be especially sensitive to a problem like that, considering his own sister was dying of a medical condition. Unless he just figured that the strong would survive and build immunity or something.
  • Actually, Tsukasa confirmed in Chapter 68 that he isn't entirely against scientific civilization (he mentioned right afterwards that his village uses fire and scientific tools). He just feels that progress must be halted to an extent so that weapons of mass destruction aren't eventually created. So since he isn't against science like you claimed then I doubt he would be against medicine.
  • As an aside, Tsukasa would eventually have to halt medicine at some point. Part of the nature of pharmaceutical research involves learning how certain substances affect the human body; it would be ABSURDLY easy for a medicine man to create poisons or other biological weapons.
    • Don't forget there are also dangerous recreational drugs, M'kay?

How did petrified Senku survive his building collapse and end up in a cave?

• When Senku was first petrified, he was inside a building. So shouldn't he have been smashed to bits when the building rotted away and collapsed with him in it? How did he go from being in the upper floor of a multi-story building to being deep inside a cave thousands of years later when he was revived, and somehow managed to survive this entire transition?
  • First off: Senku wasn't revived in the cave, just near the entrance. As for how he survived the building rotting away before collapsing, I'm not sure myself. My best guess is that the stone that everyone petrifies as is strong enough to survive small falls, otherwise most of the Modern Age characters wouldn't have survived in one piece by the time the story takes place.
    • I wasn't thinking of small falls, I was thinking about the upper floors of the building collapsing on top of him. Also how did he get anywhere near a cave? There weren't any caves near the school, and they wouldn't just randomly show up after a few thousand years.
    • I'd also guess that the "stone" is just that sturdy. The manga and the anime show that a lot of things have happened while everyone was petrified so it's rather natural that they ended up at different locations after the amount of time that has passed. Depending on what exactly happened, a new cave forming should be possible.
    • Just to clarify, the school building Senku was in didn't have a chance to collapse as a nearby dam/reservoir degraded and the ensuing flood surge hit the building, washing Senku (and Taiju) away.

Senku getting depetrified from nitric acid from the cave?

• How did the drops of nitric acid get on his stone body when he was a short distance outside of the cave? Or to ask that from a different perspective, why did Senku think to investigate the cave instead of the immediate area (ground and trees?) around him?
  • The nitric acid has probably been dropping for quite a while in the cave so it's likely that there were some traces of it in the ground where Senku was. Senku most likely checked out the cave because it was what stood out the most in his immediate area. I'd at least think that a cave would stand out.
  • Also, a cave would be a good point to check out as a possible form of shelter, so he'd want to see if he could use it.

Measurement and units

• How does Senku measure the amounts of chemicals he uses or makes? He could just pick a certain weight and say "this is the gram now" (and likewise with volume), but we don't see him using a scale or anything. One of his glass instruments does have lines on it though, indicating volume measurements. Likewise, how would he know what percentage ethanol the alcohol he distilled was, or how hot the furnace was, without modern tools like thermometers? He can tell if it's "hot enough to melt a certain material", but sometimes you need to be more precise.
  • The metric system is designed around specific measurements, all related to each other. A gram is not a random weight that someone decided to use as a baseline (unlike the imperial pound), it was defined as "the absolute weight of a volume of pure water equal to the cube of the hundredth part of a metre, and at the temperature of melting ice." The definition has shifted to rely on the Planck constant, but Senku could easily measure out the original definition, and then from there calculate the rest of the metric system.
  • In the South America arc it's revealed that right after reviving he made a measuring stick of a known length (his height of 171cm). He then used that to determine a kilogram (a cube of water 10cm to a side). 1 kg of water is also 1 liter giving him volume. Alcohol percent is measurable through specific gravity (a simple hydrometer would be easy to make and calibrate from the materials available).
    • This is the same methodology current SI units are defined. This keeps most of the current science we know intact. You define one unit using a measuring stick - Senku's height for meters in universe or a specific spectrum line of a cesium atom for seconds IRL. Then you pick a bunch of physics constants and set their values to define other units - set water's density to constant to define kilograms from meters in universe or set speed of light to constant to define meters from seconds.

Arbitrary facial hair

• I get that most young males in manga have a Perma-Shave to indicate youth, but why do some of them (Taiju, Chrome) grow facial hair while others, like Senku, Tsukasa, Gen, and Ukyo, don't? If the implication is that all of them shave, why do we only see Taiju doing it? We know Chrome shaves because he had stubble after the all-nighter inventing the waterwheel.
  • Law of Conservation of Detail. We see Taiju doing it, so we know it's possible, and can assume everyone without facial hair shaves.
    • Some men just don't grow facial hair too. Not every man needs to shave.

Effects of Depetrification

• With recent reveals at the time of this writing, we now know that the petrification can actually save someone from death itself. Person can be dead, and be brought back. We know from Kaseki that it also seems to renew one's life in a beneficial way. So why do characters with eyesight issues still have them after being revived? Is it due to the way their bodies are simply made, that their eyes can't be re-shaped by it? In which case could it cure diseases you get later in life? IBS, diabetes, etc?
  • Given how it doesn't de-age people, it does seem to have limits. And, given how it was able to heal that one girl's brain, it can do a lot. From what has been shown, it seems to be revert injuries and damage, not things "natural" to the body. So for stuff like Diabetes, it would depend on the cause. Damage to the pancreas could be healed, but a simply unhealthy body, not so much. The same could reasonably be applied to eyesight. Damage done to the eye would be healed, but if they were naturally near or far sighted, that wouldn't change.

Yuzuriha's headband

• I know this has been joked about, but what the heck is Yuzuriha's headband made of that it can stay undamaged for 3700 years, when everything else disintegrated?
  • Presumably it's high-quality plastic. Now, even the strongest plastics are only estimated to last six hundred years or so, but she was largely protected by that tree.

Empire of Might's architecture

• The fortress/cave system inhabited by the Tsukasa Empire appears to be made of huge stone beams crisscrossing each other. How did they move these beams? Even Tsukasa wouldn't be able to move one of those (maybe Senku could with very strong pulleys). It's highly unlikely that it formed that way naturally, and there's nothing in the architecture of the Roppongi Hills Mori Tower (the former site, according to the wiki) that looks like that, never mind it collapsing a few hundred years after the petrification.
  • Maybe random weird geological disturbances after 3700 years made the area look like that under all the vegetation. The Empire seems to have quickly stripped all vegetation in their immediate vicinity for their own use. Alternatively, it's pure Artistic License. You'll note that absolutely no one mentions the huge crisscrossing beams, so maybe in reality the place looks pretty normal but we got the supervillain lair to demonstrate the Empire's military superiority.
  • Though it really hasn't come up, there's also how the remains of society would affect things like formation of landmasses. The Eruption of Fuji is the closest we've gotten, but all those stone beams could have begun forming due to collapsed skyscrapers, or other such manmade structures falling and decaying. Time got rid of all identifying features, leaving only the strange stone beams.

Tsukasa's Insane Luck

• Somehow, through luck or psychic abilities or some kind of situation where every gifted person in Japan knows each other, Tsukasa seems to have an extremely impressive array of adult-hating borderline-superhumans who want to die of easily-preventable infections (or childbirth). Martial artists, a gymnast (who also has all the analysis and stealth abilities of a standard-issue ninja, including the danger sense), the list goes on. But the story goes on to repeatedly assert that Tsukasa chooses his revival subjects for their abilities — so how does he know that a naked petrified man (or... extremely unlikely teenaged submariner) has exceptional hearing? Is he just tremendously lucky or something?
  • If you want to be uncharitable to him...trial and error. He revives people at random and if they're suitable for his empire then welcome to the future. If not...well a quick does if neck snapping stops them being a problem permanently.
  • Some of the first people Tsukasa released were Gen Asagiri, a mentalist that can convince people of most anything, and Minami Hokutouzai, a reporter with a lot of intel on various people. Between Minami’s intel and Gen’s manipulations, anyone they awakened would have more than likely just listened to Tsukasa because what other option was there?