When Salazar Slytherin invoked the Parselmouth curse upon himself and all his children, his true plan was to ensure his descendants could trust one another’s words, whatever plots they wove against outsiders.
You have two parents, four grandparents, eight grandparents, etc.
A generation is 20-25 years (depending on how young people have children)
Salazar Slytherin lived one thousand years ago.
In short, today either every wizard in Britain is a descendant of Salazar Slytherin or none is.
It seems awfully convenient for Quirell to suddenly have a foolproof way to make Harry believe certain claims. It seems to me that the whole “snakes can’t lie” thing would have been revealed when Quirell was trying to convince Harry he didn’t want to kill Bahry in Azkaban. In fact, that would have shortened that particular discussion considerably, in a situation where time was essential. It has already been established that ventriloquism and silencing charms exist and that Quirell can do silent and wandless spell casting, so the “two plus two” test could easily have been faked.
Iirc, in canon, the Gaunt family (Voldemort’s family) was the last living set of descendants of Salazar Slytherin, and they were very inbred by the time of the books, so it appears that JKR at least provided some workaround for this.
As for the reliability of Parseltongue, there’s some precedent for it apparently serving as truth-enforcement. Chapter 49:
“I am not regisstered,” hissed the snake. The dark pits of its eyes stared at Harry. “Animaguss musst be regisstered. Penalty is two yearss imprissonment. Will you keep my ssecret, boy? ”
“Yess,” hissed Harry. “Would never break promisse.”
The snake seemed to hold still, as though in shock, and then began to sway again.
[...]
“You ssay nothing, to no one. Give no ssign of expectancy, none. Undersstand?”
Harry nodded.
“Ansswer in sspeech.”
“Yess.”
“Will do as I ssaid?”
“Yess.”
Professor Quirrell is known for his aversion to unnecessarily redundant conversation, so it seems likely here that he wants to be sure Harry is telling the truth. Later, in Chapter 66:
“Lessson I learned is not to try plotss that would make girl-child friend think I am evil or boy-child friend think I am sstupid,” Harry snapped back. He’d been planning a more temporizing response than that, but somehow the words had just slipped out.
It would have helped Quirrell convince Harry in Azkaban, but it’s possible he thought it would be more useful for Harry not to know yet how much information his unwittingly-true answers were giving Quirrell.
Quirrell didn’t reveal that he’s a Parselmouth but instead went through the road of transforming in a snake that might not be bound by the Parselmouth truth saying bind.
Ssnake Animaguss not ssame as Parsselmouth. Would be huge flaw in sscheme.
I think this is strong evidence for Quirrell being bound by the same rules in animagus form. Discounted because he could have very easily been lying there.
The argument from number of descendants equally applies to the question “Why isn’t every wizard in Britain, or none of them, a Parselmouth?” It does not make any particular feature of being a Parselmouth more likely.
What is the number one piece of advice we give people about relationships? The one rule which is regarded as the key to success and happiness in romance?
Its honest communication.
Salazar’s decendants can have a perfect, magically enforced, version of that. And all they have to do is marry their cousin. The family wasn’t obsessed with blood purity at all, it is simply that after growing up in a household where harmony was routinely established via this glorious gift of Salazar, the very idea of intimacy with anyone that this could not be shared with was usually repugnant.
That’s why Quirrel calls it a curse. It lead the entire clan down a path of inbreeding! Unintentional consequences are unintentional.
Canon!Salazar is a bloodpurist already. He and the other founders of Hogwarts have a big row about it- who should be able to attend Hogwarts? Only the pureblooded! Apparently this is the reason why he built the chamber of secrets in the first place… Awesome theory otherwise.
That’s why Quirrel calls it a curse. It lead the entire clan down a path of inbreeding! Unintentional consequences are unintentional.
Perhaps — but in canon, Voldemort himself is not a pureblood. For that matter, his mother was not exactly raised to know how to have healthy relationships.
Riddle was born out of the near-final collapse of the bloodline. Grandparents were awful because of over 500 years of insularity and intermarriage. Mother whammies cute boy as escape tactic / because she’s just seriously fucked up. But because his mother conceived him with someone not from the family, he ends up the first scion in, well, most likely centuries to be born with good health. Physically, anyway.
That’s not how inbreeding works, though… If one of your parents’ family (in Voldie’s case, his mother) has been inbred for generations but the other parents has a completely different gene pool, then you should be fine. Inbreeding just makes it more likely that you have two of the same recessive allelle (which is bad in many situations), but Voldie only got one of each from his mother.
That is only if all deleterious alleles are recessive. Though of course, we don’t have any numbers and can imagine anything.
ETA: and a single recessive deleterious allele in the father’s genome would have disproportionate consequences. Although there would be about 50% chance of getting it, humans carry lots of such stuff, so overall probability of weak (but at least viable) progeny should still be high enough.
Inbreeding just makes it more likely you get two of the same allele (with bad consequences if said allele is deleterious), it does not make it inherently more likely that any single allele you have is deleterious.
True. And a progressively large portion of progeny would die before procreating, exactly because of that. Maybe there would even be bottlenecks along the way.
Yet it seems to me that a squib (?) whom Merope chose could have a different set of heterozygous=hidden deleterious alleles, which in Merope’s genome would not have been eliminated yet, but getting close to it.
Also, how on Earth was Slytherin’s curse even inherited? It would be something outside of genes, since he didn’t know about their existence. So the ability would be develop undiminished with blood ‘dilution’, which means a Parselmouth cannot be seen as evidence of pure-bloodedness, which would be a blow to Draco’s belief in his father’s ethics… And in Harry’s belief in genes-only inheritance...
Now, if Salazar was secretly a woman, and only daughters would get to be Parselmouths, that would be another story...
Unlike canon, Voldie’s father in HPMoR could have lacked magical phenotype, but must have had one magic allele and at least some distant wizard/like ancestors, because of inheritance of magic in HPMOR (which is different from canon). If somebody sequenced the DNA of HPMoR version of Voldie’s father, they would find the squib genetic make-up, not muggle.
That is just a side technical note, though. The father was probably sufficiently unrelated to the mother’s family, which probably really helped with the inbreeding problems.
First, generally speaking, exponentiation of ancestry breaks down rapidly (pedigree collapse), otherwise we arrive at the absurd conclusion that any living person has a trillion great-to-the-thirtieth-grandparents. In reality, go back far enough and ancestors start occupying many positions in the tree.
Second, obvious counterexample: suppose Salazar Slytherin marries and has one child, who marries and has one child, etc...and fifty generations later, there is still only one descendant of Salazar Slytherin per generation. This counterexample can be broadened; suppose the descendants of Salazar Slytherin’s second child all died in the Black Plague. In short, it’s not the case that a distant ancestor is either everyone’s ancestor or no one’s...not until you get to mitochondrial Eve and y-chromosomal Adam, anyway, but that’s another story (and much older than 1000 years ago).
Actually, the exponentiation of ancestry proves that Salazar is the ancestor of everyone in Great Britain by the pigeonhole principle, except in your case where each of his descendants only has one child. That is an extreme outlier and not likely to happen, all things considered.
A recent paper shows that everyone who lived in Europe 1000 years ago is an ancestor of everyone living in Europe today (barring immigration of course):
We can furthermore conclude that pairs of individuals across Europe are reasonably likely to share common genetic ancestors within the last 1,000 years, and are certain to share many within the last 2,500 years. From our numerical results, the average number of genetic common ancestors from the last 1,000 years shared by individuals living at least 2,000 km apart is about 1⁄32 (and at least 1⁄80); between 1,000 and 2,000ya they share about one; and between 2,000 and 3,000 ya they share above 10. Since the chance is small that any genetic material has been transmitted along a particular genealogical path from ancestor to descendent more than eight generations deep [8]—about .008 at 240 ya, and 2.5×10−7 at 480 ya—this implies, conservatively, thousands of shared genealogical ancestors in only the last 1,000 years even between pairs of individuals separated by large geographic distances. At first sight this result seems counterintuitive. However, as 1,000 years is about 33 generations, and 2^33≈10^10 is far larger than the size of the European population, so long as populations have mixed sufficiently, by 1,000 years ago everyone (who left descendants) would be an ancestor of every present-day European.
Great Britain is a lot smaller than Europe as a whole, so it probably takes even less than 1000 years for this effect to work.
It’s true that a family tree either dies out or grows exponentially, but 2 is not necessarily the relevant exponent.
If the expected number of children an average descendant of Slytherin has is N, after 33 generations we should expect to see N^33 heirs of Slytherin. (You should think that this manipulation is suspicious as well, but it can be justified mathematically in, say, the Galton-Watson model.) Taking N=1.25 gives us only around 1500 descendants after 1000 years. And this is, if anything, an overestimate that does not take any intermarriage into account.
Powers of 2 only become relevant if you’re looking backwards from a specific person; for example, if you want to know whether two people have a common ancestor. In that respect, I (tentatively) believe the paper you link to.
One of us must be wrong; it can’t both be the case that everyone 1000 years ago is an ancestor of everyone living today, and that the average person 1000 years ago only had 1500 descendants.
I think N is closer to two or higher; assuming the average person has two children, they will have four grandchildren on average, eight great-grandchildren on average, and so on. So there really should be 2^33 heirs, though not 2^33 unique heirs; many of those heirs are just different genealogical paths to the same people.
I think if N were below two, it would be below the replacement rate and the population would shrink over time.
Indeed, I doubt that everyone 1000 years ago is an ancestor of everyone living today. I expect that everyone 1000 years ago is an ancestor of everyone [Edit: at least within a geographical region], of no-one, or is atypical in some way (for example, I expect a family that is well-off to have a number of children sampled from a different distribution, which has no reason to have mean greater than 2).
You are right, though, that across the board N has to be greater than 2 or else the global population would shrink over time. Moreover, if (when we look at Slytherin’s descendants specifically) N is 1 or less, we expect the Slytherin line to eventually die out. This leaves room for a line that neither dies out nor grows as quickly as population does overall.
True, bu 1) GB as a country has lots of immigration, 2) there are those Asian wizards sporadically mentioned before. Maybe the martial arts master whom Voldemort killed was another of Salazar’s grand(...)children, and the girl living ‘where they don’t get invitations to Hogwarts’ is yet another one?
(Or maybe she’s a resurrected, Obliviated and Time-turned Hermione. After all, Quirrell didn’t say he will restore her to Harry, andsuch a resolution would, from Harry’s point of view, equal the destruction of Hermione’s self and so a sacrifice large enough… Though that would violate restrictions on Time-turners).
On the other hand, it seems redundant of them to have discussed the possibility of a dying wizard making an Unspeakable Vow, and an opportunity for it not arising before the end).
The pigeonhole principle doesn’t say what you want it to. It guarantees that some ancestors will show up multiple times on everyone’s trees; it does not guarantee or even suggest that every ancestor present on anyone’s tree is present on everyone’s trees.
That aside, it’s not clear that the descendants of Salazar Slytherin would mix sufficiently with the rest of magical Britain in 1000 years of wizard generations (possibly longer than Muggle generations, given differing lifespans) for the paper’s findings to apply. Running with general experimental assumptions is not effective for specific and extraordinary cases.
You have two parents, four grandparents, eight grandparents, etc.
A generation is 20-25 years (depending on how young people have children)
Salazar Slytherin lived one thousand years ago.
In short, today either every wizard in Britain is a descendant of Salazar Slytherin or none is. It seems awfully convenient for Quirell to suddenly have a foolproof way to make Harry believe certain claims. It seems to me that the whole “snakes can’t lie” thing would have been revealed when Quirell was trying to convince Harry he didn’t want to kill Bahry in Azkaban. In fact, that would have shortened that particular discussion considerably, in a situation where time was essential.
It has already been established that ventriloquism and silencing charms exist and that Quirell can do silent and wandless spell casting, so the “two plus two” test could easily have been faked.
Iirc, in canon, the Gaunt family (Voldemort’s family) was the last living set of descendants of Salazar Slytherin, and they were very inbred by the time of the books, so it appears that JKR at least provided some workaround for this.
As for the reliability of Parseltongue, there’s some precedent for it apparently serving as truth-enforcement. Chapter 49:
Professor Quirrell is known for his aversion to unnecessarily redundant conversation, so it seems likely here that he wants to be sure Harry is telling the truth. Later, in Chapter 66:
It would have helped Quirrell convince Harry in Azkaban, but it’s possible he thought it would be more useful for Harry not to know yet how much information his unwittingly-true answers were giving Quirrell.
And might possibly have prompted Harry to insist on hearing about Bellatrix in Parselmouth.
Quirrell didn’t reveal that he’s a Parselmouth but instead went through the road of transforming in a snake that might not be bound by the Parselmouth truth saying bind.
I think this is strong evidence for Quirrell being bound by the same rules in animagus form. Discounted because he could have very easily been lying there.
The argument from number of descendants equally applies to the question “Why isn’t every wizard in Britain, or none of them, a Parselmouth?” It does not make any particular feature of being a Parselmouth more likely.
.. I have a theory about that.
What is the number one piece of advice we give people about relationships? The one rule which is regarded as the key to success and happiness in romance?
Its honest communication.
Salazar’s decendants can have a perfect, magically enforced, version of that. And all they have to do is marry their cousin. The family wasn’t obsessed with blood purity at all, it is simply that after growing up in a household where harmony was routinely established via this glorious gift of Salazar, the very idea of intimacy with anyone that this could not be shared with was usually repugnant.
That’s why Quirrel calls it a curse. It lead the entire clan down a path of inbreeding! Unintentional consequences are unintentional.
Canon!Salazar is a bloodpurist already. He and the other founders of Hogwarts have a big row about it- who should be able to attend Hogwarts? Only the pureblooded! Apparently this is the reason why he built the chamber of secrets in the first place… Awesome theory otherwise.
Perhaps — but in canon, Voldemort himself is not a pureblood. For that matter, his mother was not exactly raised to know how to have healthy relationships.
Riddle was born out of the near-final collapse of the bloodline. Grandparents were awful because of over 500 years of insularity and intermarriage. Mother whammies cute boy as escape tactic / because she’s just seriously fucked up. But because his mother conceived him with someone not from the family, he ends up the first scion in, well, most likely centuries to be born with good health. Physically, anyway.
By all rights, Volde should be an inbred retard, not a genius dark lord.
That’s not how inbreeding works, though… If one of your parents’ family (in Voldie’s case, his mother) has been inbred for generations but the other parents has a completely different gene pool, then you should be fine. Inbreeding just makes it more likely that you have two of the same recessive allelle (which is bad in many situations), but Voldie only got one of each from his mother.
That is only if all deleterious alleles are recessive. Though of course, we don’t have any numbers and can imagine anything.
ETA: and a single recessive deleterious allele in the father’s genome would have disproportionate consequences. Although there would be about 50% chance of getting it, humans carry lots of such stuff, so overall probability of weak (but at least viable) progeny should still be high enough.
Inbreeding just makes it more likely you get two of the same allele (with bad consequences if said allele is deleterious), it does not make it inherently more likely that any single allele you have is deleterious.
True. And a progressively large portion of progeny would die before procreating, exactly because of that. Maybe there would even be bottlenecks along the way.
Yet it seems to me that a squib (?) whom Merope chose could have a different set of heterozygous=hidden deleterious alleles, which in Merope’s genome would not have been eliminated yet, but getting close to it.
Also, how on Earth was Slytherin’s curse even inherited? It would be something outside of genes, since he didn’t know about their existence. So the ability would be develop undiminished with blood ‘dilution’, which means a Parselmouth cannot be seen as evidence of pure-bloodedness, which would be a blow to Draco’s belief in his father’s ethics… And in Harry’s belief in genes-only inheritance...
Now, if Salazar was secretly a woman, and only daughters would get to be Parselmouths, that would be another story...
I actually do understand genetics, but I forgot that Voldie had a muggle father. Been a long time since I read canon HP.
Unlike canon, Voldie’s father in HPMoR could have lacked magical phenotype, but must have had one magic allele and at least some distant wizard/like ancestors, because of inheritance of magic in HPMOR (which is different from canon). If somebody sequenced the DNA of HPMoR version of Voldie’s father, they would find the squib genetic make-up, not muggle.
That is just a side technical note, though. The father was probably sufficiently unrelated to the mother’s family, which probably really helped with the inbreeding problems.
That’s not how ancestry works.
First, generally speaking, exponentiation of ancestry breaks down rapidly (pedigree collapse), otherwise we arrive at the absurd conclusion that any living person has a trillion great-to-the-thirtieth-grandparents. In reality, go back far enough and ancestors start occupying many positions in the tree.
Second, obvious counterexample: suppose Salazar Slytherin marries and has one child, who marries and has one child, etc...and fifty generations later, there is still only one descendant of Salazar Slytherin per generation. This counterexample can be broadened; suppose the descendants of Salazar Slytherin’s second child all died in the Black Plague. In short, it’s not the case that a distant ancestor is either everyone’s ancestor or no one’s...not until you get to mitochondrial Eve and y-chromosomal Adam, anyway, but that’s another story (and much older than 1000 years ago).
Actually, the exponentiation of ancestry proves that Salazar is the ancestor of everyone in Great Britain by the pigeonhole principle, except in your case where each of his descendants only has one child. That is an extreme outlier and not likely to happen, all things considered.
A recent paper shows that everyone who lived in Europe 1000 years ago is an ancestor of everyone living in Europe today (barring immigration of course):
Great Britain is a lot smaller than Europe as a whole, so it probably takes even less than 1000 years for this effect to work.
It’s true that a family tree either dies out or grows exponentially, but 2 is not necessarily the relevant exponent.
If the expected number of children an average descendant of Slytherin has is N, after 33 generations we should expect to see N^33 heirs of Slytherin. (You should think that this manipulation is suspicious as well, but it can be justified mathematically in, say, the Galton-Watson model.) Taking N=1.25 gives us only around 1500 descendants after 1000 years. And this is, if anything, an overestimate that does not take any intermarriage into account.
Powers of 2 only become relevant if you’re looking backwards from a specific person; for example, if you want to know whether two people have a common ancestor. In that respect, I (tentatively) believe the paper you link to.
One of us must be wrong; it can’t both be the case that everyone 1000 years ago is an ancestor of everyone living today, and that the average person 1000 years ago only had 1500 descendants.
I think N is closer to two or higher; assuming the average person has two children, they will have four grandchildren on average, eight great-grandchildren on average, and so on. So there really should be 2^33 heirs, though not 2^33 unique heirs; many of those heirs are just different genealogical paths to the same people.
I think if N were below two, it would be below the replacement rate and the population would shrink over time.
Indeed, I doubt that everyone 1000 years ago is an ancestor of everyone living today. I expect that everyone 1000 years ago is an ancestor of everyone [Edit: at least within a geographical region], of no-one, or is atypical in some way (for example, I expect a family that is well-off to have a number of children sampled from a different distribution, which has no reason to have mean greater than 2).
You are right, though, that across the board N has to be greater than 2 or else the global population would shrink over time. Moreover, if (when we look at Slytherin’s descendants specifically) N is 1 or less, we expect the Slytherin line to eventually die out. This leaves room for a line that neither dies out nor grows as quickly as population does overall.
True, bu 1) GB as a country has lots of immigration, 2) there are those Asian wizards sporadically mentioned before. Maybe the martial arts master whom Voldemort killed was another of Salazar’s grand(...)children, and the girl living ‘where they don’t get invitations to Hogwarts’ is yet another one?
(Or maybe she’s a resurrected, Obliviated and Time-turned Hermione. After all, Quirrell didn’t say he will restore her to Harry, andsuch a resolution would, from Harry’s point of view, equal the destruction of Hermione’s self and so a sacrifice large enough… Though that would violate restrictions on Time-turners).
On the other hand, it seems redundant of them to have discussed the possibility of a dying wizard making an Unspeakable Vow, and an opportunity for it not arising before the end).
The pigeonhole principle doesn’t say what you want it to. It guarantees that some ancestors will show up multiple times on everyone’s trees; it does not guarantee or even suggest that every ancestor present on anyone’s tree is present on everyone’s trees.
That aside, it’s not clear that the descendants of Salazar Slytherin would mix sufficiently with the rest of magical Britain in 1000 years of wizard generations (possibly longer than Muggle generations, given differing lifespans) for the paper’s findings to apply. Running with general experimental assumptions is not effective for specific and extraordinary cases.