Thank you seiryu, for making this thread. It would be nice to have more participants in following discussions and theories, the themes you've mentioned are interesting to discuss after all!
(My last read manga chapter was 172)
Hmm, how to start... I will pick up from our last post in the thread of Dr. Stone, it was manga chapter 171. I'm going to talk only about one of the themes for now mostly... after writing it, it turned out to be quite an enourmous text, so other themes may come later.
I use Dr. Stone wiki and manga itself to confirm my following theory quite often, so it can seem sometimes as a summary of the story at first glance. But I use these facts to build the whole picture (somehow), hopefully it's at least a bit interesting
Who are the people living on Treasure Island, what is their origin?
The primary origin of people from Treasure Island was already hinted in manga and actually even in anime. To be more specific, check out the chapter 59 of manga or the last episode of the 1st season of anime (time capsule part). In the mentioned part of the story Senku discovered what is the origin of gravestones of Ishigami village's ancestors (such as Byakuya's gravestone), these gravestones are placed near Ishigami village, in Japan. There was shown that Byakuya's gravestone wasn't just a stone, but a glass record perserved in concrete (side info - concrete was used for preservation even on Treasure Island in the "treasure chest"). Senku realized this fact thanks to the encrypted message of his father (Gen solved this cypher), which was handed over through many generations of Ishigami people, in the Hundered stories, to be even more specific - in the 100th one of a name: Ishigami Senku. Why am I meantioning the gravestones? Don't worry, I'm getting to it - Senku in this chapter also said, the gravestones were the only things taken from their original home, home where their (Ishigami people's) ancestors were living in the past. The gravestones were meant to be a momento, something sacret to the Ishigami people and placed near the village, in the center of the current Ishigami graveyeard. This comment actually confirms that Byakuya didn't make it to Japan, or rather, he didn't die in Japan where his gravestone is currently put, but died somewhere else.
And because of that I believe Byakuya died on Treasure Island and Treasure Island is the origin of the first Ishigami people. That's why - people living on Treasure Island could be related to Byakuya and other astronauts. To confirm this statement, you can check out chapter 45. There is told the story of Byakuya in basic outlines. You can notice there is the black round thing in some panels, it's a space shuttle Soyuz they used to travel from space station to Earth. They arrived in water first, but later manged to bring the shuttle ashore on Treasure Island and use it in various situations (like making the record). This shuttle was actually mentioned in chapter 101 too and it was named "Treasure chest" by Senku, because it should have contained various minerals, especially platinum Senku needed for the Revival fluid. It was an important info mentioned in the Hundered stories (or rather it was passed through Ruri, the story didn't have a name or number).
Another lead (indicating that people living in Ishigami village migrated there from Treasure Island) was the name of Soyuz, the villager of Ishigami village - he wasn't named after any mineral as others were, but actually after the shuttle itself. Because of Soyuz's marvellous memory, Senku and others could find the Treasure Island (to get the platinum). This and prior paragraph actually explaines why Treasure Island is named "treasure", it's because of this shuttle Soyuz that contains various minerals (treasures) Byakuya was gathering all of his life. I will point out now some of other leads indicating Treasure Island was the place, where space team lived.... and died. (now I don't count the 2 members who left for medicines and never came back)
The leads are:
- The shuttle is shown for example in chapter 115, where Byakuya is already very old, but still gathers minerals. Byakuya said that he will put minerals in this "round thing" and in the background of one panel is shown the shuttle. He was gathering minerals in glass bottles and one of them is shown later in the Treasure Island arc.
- During this arc, Kohaku had a mission to brake into the treasure chest (Soyuz) in the center of the island, where platinum should have been stored and steal it. She was using the quiet detonation technique to accomplish such a mission and when she broke through the concrete inside Soyuz, she found the glass bottle with sand-like substance Byakuya used to gather, containing the platinum. This is the bottle I mentioned in the previous note.
- Plus this "concrete technique" of preservation was actually mentioned when Senku was talking about "gravestones", he actually found the record made from glass bottle also in the concrete shell (in the time capsule), and back then it was discovered in Ishigami village.
So with these facts there is a great possibility people living on Treasure Island are descendants of Byakuya and others, at least the primary origin could be explained so, and they founded the Petrification Kingdom. But there is a huge question mark - why all of them are black-haired but Ishigami people mostly blond? Most of the space team were blond people, one had dark brown hairs (Connie), Byakuya actually white, even tho being a Japanese, who tend to have brown, black hair. Plus people on Treasure Island behaved "caveman-like", they didn't know much about Ishigami founder, any technology or any of his stories/legacy (at least it wasn't told so). Now that brings us some new possibilites...
We should take note of the fact that Treasure Island is near Japan - it was mentioned in manga and you can check it in Dr. Stone wiki too, so it wouldn't be surprising, if some descendants of the space team made boats to travel the distance to the place, where Ishigami village is situated in the present, and that is in Japan as I've mentioned before. (Ishigami people are said to be great sailors after all.) But considering the diverse appearence of both branches of these descendants (one stayed on the Island, one traveled to Japan), I believe the Treasure Island might have been populated by other imigrants who were revived in Japan, in similar way as Senku was or by other way we're not aware of. It would have to happen quite a long time ago, because the technology of Treasure Island wasn't advanced at all and people didn't know about technology (I don't count Medusa, because of the explanation in Matsukaze's story - they didn't know about Medusa before its attack and that was only few hundreds years ago).
People on Treasure Island could be also a mix, because of their different culture. But that could be also explained by the isolation (life on the island brings limits to the actual developement) and of course its rule does a lot too. There could be just one usurper, dictator who would order to wipe any reminder of the ancestors and make new ones, to strenghten his rule by "uncovering the real ancestors" or something like that, building the tribe's pride and new law, customs.
To take this mixing from the "blond" point of view, taking note of a similarity with the space team. There actually were people who were very similar to people from Ishigami village. Matsukaze was working for Master, who was a spitting image of Ginro, Ishigami villager. True, it was few hundreds years ago, but we didn't see all of the people living on Treasure Island, so we can't tell, if all of them are black haired or not. I even believe many of the petrified people around the Treasure Island might be the descendants of Byakuya and others and some of them will know about Ishigami branch, or at least part of the prior petrified ones will. When we return to Soyuz, who is trying to fulfill the de-petrificating mission right now on Treasure Island, we will surelly see things more clearly.
Well, I should wrap it up, it could still be discussed further, but I will leave it for some other time.
I will go a bit side-track and react to a part of the mentioned post of yours, Seiryu, where you said Medusa that was used on Treasure Island by Ibara worked on different basis than the Medusas Matsukaze was talking about, and which he destroyed back then. It can't be said for certain (that it's working differently) - Matsukaze stated himself he was not sure if there was a voice order or not or if someone found the function by testing, that's why even we can't tell surelly that the only Medusa Matsukaze didn't destroy, wasn't the one Ibara later used. It would be actually logical, if it was the same one, because Matsukaze's people (or rather his enemies) ordered Medusas with their voices, so did Ibara.
And when there was a mention of Ibara and Why-man. I'm still not sure, if Ibara had any instructions actually, I somehow still suspect him stealing the device after he found out its function and abusing its power for his well being rather than him achieving some sort of instructions or co-working with Why-man. Only time will tell tho...