Why aren't Muggles extinct?

Question

One of the basic premises of the Potterverse is that Muggles are much, much more common than wizards. This is what in part necessitates the need for the Wizarding world to hide itself away because, despite their superior powers, they would be overwhelmed by the far more massive Muggle population should conflict break out.

However, we also know that wizards and witches have been around a long time. In Prisoner of Azkaban, Hermione's letter mentions:

I bet he’s learning loads, I’m really jealous – the ancient Egyptian wizards were fascinating.

Given that in one of Ron's letters, the Pyramids were mentioned as magical locations, this means that while we don't have a definitive date of when wizardry entered the world, we can definitively say that wizards and witches have been around since at least 2500 B.C. Most likely they have been around much longer than that.

I could not find any evidence that suggests that magical people reproduce any faster or slower than a Muggle. Furthermore, being born to magical parents almost always means the child will also be magical (Squibs are considered very rare). While I don't have statistical evidence, it seems that merely having only one magical parent is enough to make it likely that the child will have magical abilities - based on Severus Snape, Seamus Finnigan, and of course, Tom Marvolo Riddle. Finally, there are of course Muggle-Borns, which while they are certainly very rare as a percentage of the Muggle population, they seem quite common enough at Hogwarts.

Finally, it's fairly easy to make the argument that Wizards are more powerful than Muggles in ancient times, given the lack of Muggle technology. In the modern era, there are arguments that Muggle weapons have exceeded Wizarding power, though there is not total consensus on this. It would be hard to argue, however, that Muggles had superior power (via technology) than Wizards prior to the 20th century.

In summary:

• Magical people have been around for at least 4500 years, probably longer.
• Magical people reproduce at roughly the same rate as Muggles.
• For most of history, magical people have had superior power to Muggles.

The question:

Given these reasons, why is is it that the Wizarding population does not dominate the human population via natural selection?

In-universe answer only, please. I'm not looking for a "J.K. Rowling is bad at maths" kind of answer.

Answer 1

We don't need to argue about reproductive fitness to explain this.

Here in the real world, the fertility rate falls off as the standard of living increases. Until quite recently, the magical community has had a much higher standard of living than Muggles. (Arguably, they still do!) So we would expect their fertility rate, historically, to be similar to our modern rate.

The current British fertility rate is 1.87 births per woman. It was about 2.9 births per woman at one point in the 1960s; it was probably higher still earlier on, but let's take that as a reasonable number for Muggle fertility, and the current number as a proxy for Magical fertility. (It seems reasonable, perhaps even a little too high, based on what we know from the books.)

Suppose that on average one in every two magical people marry Muggles; that seems like a slightly high estimate to me, but let's go with it for now. That would increase the number of couples in the magical community by 50%, e.g., if the birth rate was exactly 2 the effective birth rate would be 3:

That makes the effective birth rate about 2.8, nearly but not quite keeping up with the nominal Muggle rate of 2.9.

Obviously this all depends on what numbers you choose. But it is plausible.

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Addendum:

As PlasmaHH and Adam point out in the comments, fertility rate isn't really the best statistic to be using here, because it doesn't take into account the number of people dying before reaching reproductive age. However, I don't think this makes my argument implausible, just slightly more subtle: you have to take into consideration that fertility may be affected by both mortality rates and standard of living.

(In particular, I don't believe the mortality rate for children has changed enough since 1960 to explain more than a fraction of the drop in the fertility rate over the same period, so those figures are probably still good enough to establish plausibility.)

The effect of mortality rates on fertility can be expected to cancel itself out, leaving only the standard-of-living effect as relevant. It seems reasonable to suppose that the adjusted fertility rates (counting only children who survive to reproduce) might remain different enough to counteract the growth rate of the magical community due to Wizard-Muggle marriages.

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References: this Google chart based on data from the World Bank.

Answer 2

It's very possible that a lot of "muggles" just didn't know they were wizards.

The book that admits students to Hogwarts needs concrete evidence of a child using magic before it will write them down as being accepted to Hogwarts. That book was put there (and likely created by) the founders of Hogwarts.

Since Hogwarts was founded just over 1000 years ago, and is likely one of the oldest (if not the oldest) establishments, before this the only way a wizard or witch would be taught magic was by home schooling, which is still used in most countries.

Therefore unless a child is born to a wizard family that knows they are wizards, they will not be taught magic. And with a family of one muggle/ one wizard, the parents may choose not not to ever teach their child to use magic.

There may even be many more muggle born children than are shown in the books, but because they don't show any signs of magical ability before the age of 11 they are just never selected to learn how to use it.

So given that children outside of wizarding families would only ever have been told they were wizards for the last 1000 years, there will only have been children growing up in wizarding families learning magic. This severely limits the population of actual magic using wizards until around 900AD, and even that is only in Britain.

Answer 3

Disclaimer, I am not that familiar with Harry Potter nor a evolutionary biologist, but I would suspect that characters reproduce via sex like real humans, so a out-of-verse explanation would be a in-verse explanation.

Generally speaking, natural selection that leads to speciation only occurs in bottleneck population, or isolated population (numbering in the thousands). These population are small enough to have the trait/mutation to be present in the most of population, prior to migration or expansion.

Even if we talk about 4000 BCE there were millions of people. Far too many for a tiny population of magical beings to genetically alter a large portion of the human population. Generally speaking most humans don't live very far from where they were born, there may be cultural taboos about marrying/reproducing outside your culture. All these things curb genetic movement.

Finally does being magically actually confer a positive to genetic fitness? On the surface, being super strong and able to run really fast might seem like a genetic positive, but it might mean it takes more food to feed me, or I die at a young age which might negate the positives. Sometimes improving genetic fitness requires what might be seen as a regression. I.e., growing smaller brains due to the lack of food but you live to reproduce or cave shrimp losing eyes because there is little use for them and it cost energy to grow and maintain them.

A easily confused concept about evolution is that evolution doesn't have a purpose or end-goal. It is not trying to select for the best traits ever to make the best creature ever; it is simply selecting for the minimally best trait that helps that creature survive in its current environment.

Unless being magical leads one to being a prolific lover, and with 7+ billion people, a very prolific lover, I don't see why magical beings would take over the human population short of artificial selection. Though one specific case to note, though the affected population is still small overall and this might be considered a case of artificial selection via genocide/cultural-war.

Together, I would say unless the author decides to put on her biologist and or anthropologist hat and really fill out the lore there is not enough information to work out why exactly magical being haven't been selected given our current knowledge of how evolution works.

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Why magic may not help you evolutionarily in a shallow example:

Say there are three people, one with a congenital hand deformity, a 'normal' human, and a magical human. There is a field of blue berries that they can pick to eat to fulfill their daily Caloric (kJ energy) intake. The person with the hand condition cannot pick enough to feed himself, he dies before he can reproduce; the genetic fault dies with him. The 'normal' human picks enough berries and lives to reproduce. The magical human picks the berries with a magical spell and lives to reproduce.

There is little reason why the magical ability would be selected over the 'normal' ability, in both instances both humans live to reproduce. Unless being magic specifically helps you survive and not just merely a convenience, there would be little pressure to select for being magical. This would be especially true in the modern world were pressures of food gather and surviving against apex predators are not as present.

Answer 4

We can only speculate of course, but it seems that having magic opens you to a new world of diseases and predators that don't affect muggles. That could be the reason why they didn't become dominant, say after the black pest.

As an example,this is the classification the Ministry proposes for magical creatures:

X: Boring

XX: Harmless / may be domesticated

XXX: Competent wizard should cope

XXXX: Dangerous / requires specialist knowledge / skilled wizard may handle

XXXXX: Known wizard killer / impossible to train or domesticate

We muggles certainly didn't need this kind of classification for a long time.

Answer 5

A curb on the wizarding population is the tendency of Muggles to fear that which they don't understand, and to kill that which they fear. And in a primitive society "that which they don't understand" covers a pretty large amount of ground, from "everything beyond the bend in the river" to "that daft old woman whut lives in the cottage off in the woods, all by 'erself-like". And it's a short walk, thinking-wise, from "daft old woman" to "Witch!". And it's an even SHORTER walk from "in the cottage off in the woods, all by 'erself-like" to the ducking stool, to the tumbril, to "Before we set the wood alight to burn the evil out of thee, witch, wouldst thou care to repent of thy sins..?". Old Tom Riddle 'imself would pale at the thought o' ten thousand peasants carrying torches and pitchforks, a-batt'rin' down his castle door..! :-)

There's also the problem of the Zulu Equation. Although magicians have more individual firepower than muggles, a dead wizard is just as dead as a dead muggle. As the British found out in South Africa, having twice the firepower of the other guy doesn't make each of your troopers twice as powerful - it's more like sqrt(2) times as powerful because, as I said, dead is dead, and the guy who's two or three or ten or 100 times as powerful as someone else is just as dead when they're dead. And as the US Army discovered in the Phillipines, the guy armed with a spear charging down the hillside at you can sometimes soak up six rounds of incoming (see Colt M1892 revolver) and still survive long enough to plant the spear right in the middle of your chest. (Which led to the development of a sidearm (the Colt New Service revolver) with enough firepower to blow major pieces of charging spearman off).

Answer 6

Because magical powers are not an evolutionary advantage.

What matters is fitness, the ability to survive and reproduce, not "power", whatever that means. The dinosaurs were once the most powerful creatures on Earth, but their power didn't help them to survive when the meteor came. Rather, their size and strength became a liability when in the new landscape, and it was the much smaller mammals who survived and flourished.

Nothing we've seen about magical powers, and nothing you've said suggests that they would make Wizarding people any more fit to survive and reproduce than muggles. And, as you've acknowledged, they still reproduce at the same rates.

Answer 7

This is definitely hard to explain. If the Wizarding community interbred with muggles for thousands of years, population genetics would definitely lead us to expect that most humans alive today would be magical, since everyone would have at least some magical ancestors.

I get the impression from the books that interbreeding was uncommon in the past, even though it's now common. That would make it possible for most people to still not have any magical ancestors. The rise of interbreeding means that will change in the future, and we should expect a large increase in the percentage of the population with Wizarding abilities.

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The facts about heritability of Wizarding, as I understand it:

• Most children of two Wizard parents will be magical. (And no I'm not going to write Witch-or-Wizard everywhere. Please assume Wizard is a unisex term like Muggle.)
• Most children of Wizard + Muggle will be magical
• One Muggle parent doesn't make Squib offspring much (or at all?) more likely than for two wizard parents. (This is the most difficult part to explain with any kind of simple Mendelian genetic model.)
• Muggle-born witches and wizards are descended from Squibs who married Muggles; the magical ability unexpectedly resurfaces after many generations. (source).

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A google search for harry potter population genetics turned up a high-school science lesson plan on heritability of genetic traits using Harry Potter characters and creatures as example, published by the U.S. National Library of Medicine. The end of the second lesson (pdf) proposes a theory of heritability of magical ability where magical ability is not expressed in Muggles because they carry at least one copy of a silencing version of a gene (allele) which regulates the activity of the allele for strength of magical ability.

Their theory explains some of the phenomena from the books, but not the low rate of Squibs / Muggles from Wizard + Muggle parents. (According to their theory, every Muggle has at least one copy of the genetically dominant silencing allele, so even in the best case, children from ss(wizard) + sS(muggle) have a 50% chance of inheriting an S (silencing gene) and being pure Muggle, with not even weak magical ability. Some Muggles would carry an SS genome and be incapable of ever producing magical offspring, so clearly this model doesn't match this aspect.

Traits caused by multiple alleles have more complex behaviour, but I suspect there might not be any purely Mendelian explanation. I think the fact that children of Wizard + Muggle are no less likely to be Squibs is the hardest thing to explain. Perhaps this is a case of unreliable narrators, since the characters saying this are fighting a war against pure-blood supremacists! (And out-of-universe, I think JKR didn't want her story to include a genetic basis for discrimination.)

Perhaps at this point, interbreeding is still a new thing, and Wizards almost always have two copies of the magical allele(s). Perhaps after some generations of mixing, Muggle + Wizard will have a significantly lower chance to produce magical offspring than Wizard + Wizard.

Or maybe it's magic. Fortunately, invoking magic to explain magic is not exactly a problem, but it means we can't just use formulae from evolutionary biology / population genetics.

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The extreme heritability of Wizarding should make it spread much more easily / strongly than a normal genetic mutation. It will easily become fixed throughout a population as soon as a few Wizards are common ancestors of all living humans. (This happens after enough generations, even with limited interbreeding.)

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The most recent common ancestor (MRCA) of all humans alive today may have lived as recently as a few thousand years ago. The existence of long-isolated tribes may push that number back as far as the Upper Paleolithic, but a few thousand years or even shorter is probable if we don't worry about isolated pockets and just consider the bulk of Western civilization (the setting for Harry Potter).

At some point before the time of the MRCA, there's a point where everyone in the population is either an ancestor of everyone alive today or has no living descendants.

However, if Wizards limit their interbreeding with Muggles, the populations could stay separate. Wizardlyness can't spread throughout the Muggle population because of the practice of removing Wizards from their Muggle parents and bringing them into the Wizarding world. At that point they no longer count as Muggles, and are more likely to marry (or whatever) other Wizards.

The un-expressed form (that leads to Muggle-born wizards) could spread throughout the Muggle population, but IDK what the implications of that are. IDK if it's normal that Muggle-borns can identify a specific Squib ancestor, or if some just happen from random chance (i.e. inherited from an ancient magical ancestor many tens of generations ago, i.e. magic is just circulating in the gene pool.)

Answer 8

According to this link

Most wizards these days are half-blood anyway. If we hadn't married Muggles we'd've died out.

Let's accept that as true. Pure blood only would die out.

Muggle Wizard is more likely to produce a Wizard. This would indeed raise the Wizard population.

If a Wizard preferentially marries a Wizard they will not drive Muggle population to extinction. Wizards do preferentially marry within.

If the Wizards systematically married Muggles then the Wizard population would rise.

In summary Muggles are not extinct because Wizards tend to marry within.

Answer 9

I would place the blame on the wizarding community itself, which appears to have frequent power struggles between light and dark wizards. During Voldemort's reign of terror alone, a significant percentage of the British community was killed off. Such frequent infighting in a population would self-limit its growth through direct killings and also creating a negative environment that would discourage family formation and child-bearing to some degree.

Answer 10

Anthropological and genealogical reasoning aside, the numbers on this are actually pretty clear. There may be muggle-born wizards in the school, but from a population of many millions, any given year only has at most a few dozen.

Consider (for example) a sample size of 10000 muggles and 10 wizards. Let's say the chances of 2 wizard parents having a squib are 1:10. Let's also say the chances of 2 muggles having a wizard child are 1:10000. Even at a matched birth rate of 2.5 per couple (and dropping the previous generation), the result after 10 generations would be:

92966 Muggles Born, 9 Wizards born to Muggles, 46 Wizards born (including to muggles), 4 Squibs -- effectively multiplying the muggle population by 9.3 and the wizard population by only 4.6

Now let's tweak those ratios - 1:100 squibs and 1:1000 muggle-born. This results in: 91298 Muggles, 91 Muggle-Born, 924 Wizards, 8 Squibs

Suddenly, there are a whole lot more wizards, but even after 100 generations and tens of trillions of total people, there are 21.4 muggles for every wizard.

It would take 1:100 muggle-born (with muggle-born wizards in vast quantities) and 98 generations (as well as tens of trillions of people) before wizards actually outnumbered muggles, at 1:.999

With the actual numbers being even harsher than the initial example, the math holds up.

Answer 11

I consider there are quite a number of reasons for why the world is not dominated by wizarding population(and basically why I am a muggle :-( ):

1. Magic is not a skill that could be developed over time by training. You have to born as a wizard or a witch. And the chances of you being in the center of muggles is very high. In that scenario, even though you might realize you develop few powers, you will not know how to nurture it and grow it. Add a few more generations down the line, you might have muggle children succeeding you. Remember Trelawney saying that the art of prophecy might lose a few generations. What if the art of magic can be lost for an entire bloodline?
2. In the ancient times, people tend to live along with the "magicians" or "priests". So if you have the talent and if they train you, you can sustain those powers and be magical. If a no is on either of them, well, live as a muggle.
3. There could be civilizations of magical people living together in the past(Still thinking of Atlantis). That will be lot safer for the wizards and witches. But might have ended due to any of the natural calamities or diseases or any other reason that ends civilizations. In that case, the world will quickly turn into a more muggle population than wizarding.
4. There could be millions of people who born as magical but never found their powers at all and just died without using the power at all(you can call them Just Harry's). Not all people will have a Dinky Diddydums to chase them and let them experience their accidental magic.
5. In the medieval time, it was also became very common to burn witches and wizards. This might have reduced the populace even further.
6. Due to the medieval times, (I hope/guess) many wizards/witches started on the pure blood cr*p. Which just means, more magical people isolating from non magical, thus reducing the half blood children.
7. Hogwarts happened only a 1000 years back and so we can safely say that until then there is no centralized school that takes each and every magical children and train them. Instead, most wizarding families might have trained their children themselves and might not extended the same to any other muggleborns, if they ever found one.
8. Even now, magical people are still rare. Still Hogwarts kind of gets kids in only hundreds every year whereas it is a global school. Add Durmstrang and Beauxbatons to the mix as well and you will still find that the number might go up to a thousand or a little more per year. Muggles can beat that kind of population in minutes.

Answer 12

You don't just magically know all magic, you need talent and then have to learn it. An untrained Harry Potter without any guidance would not be significantly more likely to survive in a world where you can't just order pizza.

Discovering spells with no training without blowing yourself up is hard. Figuring out what a wand is, how to make it and having it happen to choose you is very unlikely to just happen. While magic without a wand is possible, it is much harder, especially for the untrained.

Having to hide magic from Muggles is not obvious and had to be learned the hard way. Writing books about magic (those moving images are not easy to make with just sticks and rocks) and figuring out effective ways to find and train young wizards took thousands of years, so in the early days there was just not much you could do with magic due to a lack of knowledge.

Also keep in mind that food was a major concern that took most of the population's productivity. After spending the day trying not to starve the amount of time and energy you had left to practice magic was near zero, so useful discoveries were rare.

TLDR: Just like science, magic had to be discovered in a slow and difficult process.

Answer 13

I offer a much simpler reason: the same reason pandas aren't. That is: people (specifically wizards, here) don't want to see them die off. It's the human nature of helping, which leads to people volunteering in third-world countries instead of letting them die off. No reason to hurt them, and they survive well enough alone.

Answer 14

For most of history, magical people have had superior power to Muggles.

This does not necessarily lead to Wizards out-breeding Muggles. On the contrary, it seems that having a better quality of life actually leads to a lower birth rate. Not by biological causes, but by choice.

So, your question is similar to asking why people in developed countries don't out-breed people in poorer countries, despite having superior technology. Actually, as it seems to be in our days, it's quite the opposite which is happening.

Answer 15

It is possible that the premises described simply do not necessarily lead to the conclusion in question.
For example, humans are considerably more powerful than most other forms of life on the planet.

This includes bacteria, molds, ants and many other types of insects, and a whole lot of other animals etc. Many of these were around long before humans, but there are newer species as well. Check out "The eight super-adaptable life-forms that rule our planet" for some examples; humans represent a small percentage of the population (and even biomass) compared to some of these. Inferior powers do not automatically lead to a wipeout, even long term.

Humans have the capacity to exterminate colonies of other species and even eradicate certain life-forms intentionally, and while we are now killing off a bunch of others, it's unintentional and many folks would strongly prefer we stop doing that. Intentional, systematic eradication in most cases simply does not provide marginal benefits greater than the marginal costs of doing so. This is true even for species we consider pests or which carry disease. Further, we don't necessarily understand all the follow-on effects that might occur following the loss of the "ecosystem services" that species currently provides. At least some things that Muggles build and do are useful to wizards, and that's an explicit disincentive to wiping them out, even before any ethical considerations come in.

Answer 16

1. Natural selection is not applicable to sentient species with society.

   Society (laws, standard of living, cost of living vs capita, religion, etc.) determines reproduction rate. Biologically 'superior' and mentally 'superior' in certain societies is not correlated and may be inversely proportional to reproduction rates. An exception to this is if you define 'survival of fittest' circularly such that those who survive are by definition more 'fit'. A circular definition would mean that for reasons perhaps not obvious, wizards are less 'fit' than humans. See 2. for such speculation.

2. The wizarding community is not self sufficent.

   Ron in Chamber of Secrets:

   Most wizards these days are half-blood anyway. If we hadn't married Muggles we'd've died out.

   Wizards can have non-magical children (squibs). That combined with other societal factors (evil wizards, standard of living, cost of living, etc) may explain why wizards appear to be an anomaly as opposed to a norm in society.

Answer 17

The problem is in the question: Evolutionary advantage and natural selection are irrelevant unless there's direct competition. We don't find lizards extinct simply because they're less fit than monkeys. Nor do we find that one (color) race of humans goes extinct. Nor do we find blue eyes or brown eyes eradicated.

Neanderthals are likely extinct not because they were less adapted - in fact, from what I've read, they were generally more fit on the individual level. Their winning competitors grouped up (which in itself was the more relevant advantage) - but what's important is that they were probably murdered. By agency, not evolution. Similarly, the wizarding world would have to team up on and take out the muggle world by intention and force in order for their "power" advantage to matter or become relevant.

The other half that matters is simply geographic distances - competitive love instead of competitive war. The Mongols, for example, spread their seed very intentionally. But there's plenty of reason to believe, from the books, that the wizarding world (at least mostly) kept to itself. This propensity is far more important, even if it's only slightly less than that of muggles, than fitness. Again, if the fitness isn't a matter of direct competition, it has to be a social endeavor to spread out, which doesn't seem to fit with the wizarding culture.

So, again, evolutionary fitness and natural selection are totally irrelevant to the spread of the magical genes. Until there's a war between the two camps that seeks total annihilation, at least. (At which point, having magic may not counterbalance muggle ingenuity, cooperation, individual genius, sheer numbers, or technology.)