How many people are needed to maintain equilibrium for a Mind Flayer?

[kingcheesepants]

I want to have a colony of Mind Flayers that doesn't go around hunting people but instead has a pacified population that they take care of and eat an elderly person from once a month. Let's just assume that they're already a generation or more in and thus have everything going smoothly. How many people would be needed per Mind Flayer to ensure that they were having enough children that their numbers wouldn't decrease but could instead maintain a sustainable growth rate? I'm thinking maybe like 30 breeding couples could have at least 15 children a year which would be more than the mind flayer eats and gives a margin of error in case of accidents. But then given how long it takes for kids to grow and new couples to be created, and I'm thinking that people are having a kid every other year give or take but maybe that isn't really feasible. So I don't know maybe my numbers are way off and we'd actually need like 50 or so couples per mind flayer. If any of you guys are good with math and know the sociology/biology aspects of this and can give me some numbers I'd appreciate it.

[Mastikator]

Assuming they live for 80 years, one elderly death per month you need at least 960 people, with one birth every month.

In you look at a real city, New York then the total deaths in 2017 was 155,191, the esimated population that year was 19,849,399
(source: https://www.health.ny.gov/statistics/vital_statistics/2017/table31a.htm https://www.health.ny.gov/statistics/vital_statistics/2017/table01.htm)

Extrapolating with extreme naivety from those numbers, 155191/12=12932.58 and 19849399/12932.58=1534.8, almost twice my original estimate, but that is still in the ballpark. You'd be safe in the area around 2,000 humans per mind flayer. You'll want a bit of slack space in case of emergency.

Funny, it also means that New York State could support 12932 mind flayers if they only ate once per month. That number drops to 436 if they want to eat a brain every day.

[Sigreid]

Well, lets see. Each mindflayer in your scenario needs 12 brains a year. Assuming the mindflayers are ok with eating baby brains it would take 9 months to generate a newborn so you would need at least 9 times that per mindflayer for 108. Some of the women will die in child birth, especially if they're forced to be constantly pregnant, and you'll need replacements for those as well as the ones that just age out of being a head on a water slide. They would probably need around 200 births per year to sustain their setup with security and no chance of starvation.

[Elbeyon]

I do not know if 5e gives those type of details, but in 3.5


A mind flayer must have a minimum of one fresh brain per month. Any less than that and it suffers physical debilitation, becoming so weak that it could die. Its ideal diet is one brain per week. A mind flayer that consumes one brain a week does not feel deprived. It can eat more than that for enjoyment and for the psychic boost, and it will if brains are plentiful.

Typically, mind flayers consume somewhere between the minimum of one brain per month and the ideal of one brain per week, averaging one brain every two weeks and supplementing their diet with other foods. This doesn’t sound like much, but consider the effect of a community of one hundred mind flayers. To maintain their health, they need fifty brains a week, or 2,600 brains a year. Maintaining that supply is the most important and diffi cult task facing an illithid community

[Amnestic]

From 3.5 content* an ideal mindflayer diet is 1 healthy brain per week which they could *stretch* to be 1/month, but Mindflayers don't seem to be the type to settle for less and barely subsist, they want the finer things.

So if you're maintaining population you need to be at least 52 new births per year, per mindflayer, except between disease and other things you're probably losing some along the way between birth and "ripe" feeding age, so likely more than that. If you then give couples "time off" from childbirth as you've said, then double the numbers.

So maintaining one mindflayer might need as many as 120+ breeding couples to maintain population balance with their food. If I were to pick a number, 250 people per mindflayer seems like a solid baseline. Then scale it up depending on how many mindflayers are in the colony. More than two and you're already in 'village' territory all on its own.

*

Lords of Madness:

A mind flayer must have a minimum of one fresh brain per month. Any less than that and it suffers physical debilitation, becoming so weak that it could die. Its ideal diet is one brain per week. A mind flayer that consumes one brain a week does not feel deprived. It can eat more than that for enjoyment and for the psychic boost, and it will if brains are plentiful.

[MinotaurWarrior]

The most efficient path is to eat baby brains. They need about 1 brain per month, so ~ [gestation period in months of slave race] / [fertility rate of slave race over the lifespan before they get killed] per illithid. So like about 60 or so for humans (didn't actually crunch the numbers on human fertility).

I figure this is what poor illithids ate during the height of the illithid empire. Illithids are really, really, really evil.

If they eat elderly people specifically, you basically need ~ [slave race lifespan in months] / Illithid.

[Elbeyon]

Throw in some good berries or something for good measure.

[Quietus]

I'd also point out, you want to eat those brains BEFORE they get so old and addled that they begin to degrade. I imagine an octegenarian suffering from dementia is going to be the meal equivalent of trying to make stew, but forgetting it in the slow cooker overnight. Still technically edible, but it's more a meat-flavored slurry than a delicious stew.

[Naanomi]

I'd also point out, you want to eat those brains BEFORE they get so old and addled that they begin to degrade. I imagine an octegenarian suffering from dementia is going to be the meal equivalent of trying to make stew, but forgetting it in the slow cooker overnight. Still technically edible, but it's more a meat-flavored slurry than a delicious stew.
On the other hand, baby brains are not spiced with experience and other psionic flavorings

[cutlery]

If one brain a month is baseline, I think you'd need to budget for two brains per month per mind flayer. The whole colony isn't going to exist on the brink of failure at a minimum-subsistence level.

Also, sooner or later some bored, power-mad doofus is going to create a Brainstealer Dragon (https://forgottenrealms.fandom.com/wiki/Brainstealer_dragon). Who knows how much they need to eat.

[Keltest]

On the other hand, baby brains are not spiced with experience and other psionic flavorings

Sure, but you dont necessarily want to spend 40 minutes cooking up a gourmet meal for breakfast every day, sometimes you just want a bowl of oatmeal.

On that note, Illithids are also physically capable of sustaining themselves off of Rothe or goblin brains, which are almost certainly not as flavorful but are likely much easier to obtain in large quantities, especially in the Underdark. An illithid who wants a tasty meal will go out and poach an adventurer or something. Maybe go buy a slave from the Drow if he's feeling lazy.

[Doug Lampert]

Another approach to getting an estimate is that IIRC Uganda and some other central African countries have had ~6% per annum population growth for quite awhile now. This implies that you could eat 6% of their population per year, and still be stable.

So by that estimate you'd need a minimum of 867 people per mind-flayer for each to have a brain a week. It's unlikely to work that well in practice, so I'd ~double that to 1,730 or so.

In theory, your mindflayers might try to do better by following the usual livestock rearing practice of eating young males to get the adult ratio to something on the order of 12 females per male. But this runs into the problem that fast reproducing human societies don't suffer from a shortage of wombs, they suffer from a shortage of caregivers, teachers, and skilled workers; so I think trying this would be a fiasco. But this might not stop the mindflayers from trying.

Also note that Uganda and the other countries with that kind of population growth have VERY young populations on average, so you'd not be eating just the old unless your definition of "old" is based on the society in "Logan's Run". (Where they killed everyone on their 30th birthday).

A lot of this is going to depend on your definition of "old" for when you kill people, the younger you're willing to dine on, the fewer people you need and the less you need to worry about attrition from other causes.

[MinotaurWarrior]

If one brain a month is baseline, I think you'd need to budget for two brains per month per mind flayer. The whole colony isn't going to exist on the brink of failure at a minimum-subsistence level.

But illithids live in an oppressive LE society, so the people in charge probably don't give two hoots what the average illithid wants.

Dealing with a single elder brain and its illithids on their own? Yeah, they're probably eating 4 free range brains a month. But if there is an illithid in a position to benefit from forcing other illithids to subsist on the utter minimum level of nutriment, I think they're going to take that option.

[Keltest]

But illithids live in an oppressive LE society, so the people in charge probably don't give two hoots what the average illithid wants.

Dealing with a single elder brain and its illithids on their own? Yeah, they're probably eating 4 free range brains a month. But if there is an illithid in a position to benefit from forcing other illithids to subsist on the utter minimum level of nutriment, I think they're going to take that option.

As a rule of thumb, Illithid hives that live with that level of internal strife tend to fracture and either split into distinct hives, or wage outright civil war until one elder brain is firmly in control again. Illithids can be selfish, to a point, but that point is where that selfishness endangers the Elder Brain's agenda. Threatening the overall well being of the hive qualifies.

[Sigreid]

A fairly random thought. If this particular hive has developed a psionic ability or technology that can effectively replicate the clone spell, each slave can be essentially an infinitely renewable food source.

[ff7hero]

I'm thinking the Illithids could produce and employ Warforged to act as doctors, caregivers, etc to take some of the burden off their "cattle."

[KorvinStarmast]

Funny, it also means that New York State could support 12932 mind flayers if they only ate once per month. That number drops to 436 if they want to eat a brain every day. Not so: if they tried to survive on brains in New York they'd starve.

*ducks* :smallcool:

I want to have a colony of Mind Flayers that doesn't go around hunting people but instead has a pacified population that they take care of and eat an elderly person from once a month. Do you prefer mutton over lamb?

A fairly random thought. If this particular hive has developed a psionic ability or technology that can effectively replicate the clone spell, each slave can be essentially an infinitely renewable food source. And of course Mind Flayer kids would start to complain to their mothers .... "What, Hans Gruber brain, again?!!!!"

[MinotaurWarrior]

As a rule of thumb, Illithid hives that live with that level of internal strife tend to fracture and either split into distinct hives, or wage outright civil war until one elder brain is firmly in control again. Illithids can be selfish, to a point, but that point is where that selfishness endangers the Elder Brain's agenda. Threatening the overall well being of the hive qualifies.

You're thinking too small - the illithids have / had an interplanetary empire. The hierarchy isn't just within one "hive", but even between worlds.

An elder brain with a bunch of high powered psionicists, all luxuriously eating the brains of one captive poet a week, isn't going to go down to three poets a month for the benefit of a neighboring group. Instead, they'll dominate them, force them to eat baby quaggoths, and send them out at the (relative) vanguard of their armies, to bring new worlds into the empire, from which this elite group will harvest more tasty free range poets.

[MaxWilson]

On the other hand, baby brains are not spiced with experience and other psionic flavorings

Oh, so THAT's why the Friendly Illithid Foundation sponsors college scholarships, Teach For Asgardia, and service missions abroad!


You're thinking too small - the illithids have / had an interplanetary empire. The hierarchy isn't just within one "hive", but even between worlds.

An elder brain with a bunch of high powered psionicists, all luxuriously eating the brains of one captive poet a week, isn't going to go down to three poets a month for the benefit of a neighboring group. Instead, they'll dominate them, force them to eat baby quaggoths, and send them out at the (relative) vanguard of their armies, to bring new worlds into the empire, from which this elite group will harvest more tasty free range poets.

I love this scenario! I think it works for neogis too, and possibly beholders.

[Keltest]

You're thinking too small - the illithids have / had an interplanetary empire. The hierarchy isn't just within one "hive", but even between worlds.

An elder brain with a bunch of high powered psionicists, all luxuriously eating the brains of one captive poet a week, isn't going to go down to three poets a month for the benefit of a neighboring group. Instead, they'll dominate them, force them to eat baby quaggoths, and send them out at the (relative) vanguard of their armies, to bring new worlds into the empire, from which this elite group will harvest more tasty free range poets.

Had is the key word there. In modern times, elder brains dont share territory such that dropping a poet a month would aid another colony. They aren't picking from the same food pool in the first place.

[Chronos]

I think that Ugandan population growth rate is mostly from migration, not reproduction. There are a lot of refugees there from Sudan/South Sudan.

[Doug Lampert]

I think that Ugandan population growth rate is mostly from migration, not reproduction. There are a lot of refugees there from Sudan/South Sudan.

It was from reproduction in the numbers I saw, and it's been that way for DECADES, which is too long for the war refugees to be the cause. My sister did a fellowship there a couple of years ago and said the median age was down to 16 and they're still having kids at a high rate.

[Sigreid]

They could set up kind of a logan's run scenerio. The humanoids live in peace and plenty with everything they could want believing themselves to be free and happy, but at the age of 30 they go to carosel to be renewed. Lunch is bred, but no one is raised by their parents. Some of lunch is selected to ensure everyone goes for renewal to ensure society is maintained. One is born, one is renewed. Simple, logical, perfect.

The beauty of this approach is Lunch essentially runs the farm and slaughterhouse, not realizing it is lunch.

[kingcheesepants]

Man we've got some wildly different numbers from the group but it seems my initial thought was far too small. I guess I'll go with 100 couples per Mind Flayer for now. Although that might be a bit on the low side if some of the numbers you guys are throwing out are more accurate.
The colony idea is one elder brain and a small group of mindflayers maybe 100 or less who provide security and governance and such for a town or if the higher numbers are more feasible city of people who are then taken and eaten once they pass middle age, maybe about 45 or 50. Right around the age that they can't really have more kids and their health both mentally and physically starts to notably decline. The people can choose their own mates and raise their own kids and they work farms, become teachers, craftsmen, artists etc and have a government and guard run by extremely intelligent beings capable of reading minds and providing security and justice (with a genius intellect, the ability to read minds and a lawful disposition Illithids are perfectly capable of determining guilt or innocence and delivering appropriate punishments). With the caveat that once they (the citizens) start to decline they offer themselves up to be eaten. This isn't a secret but the Mind Flayers would utilize the education and cultural institutions to make a lot of propaganda so that the people would be willing to do this as a part of their civic duty for the good of the colony.
The general idea is of this one colony trying to utilize a more neutral, slow and steady approach to expansion rather than the usual mass abductions and raiding and such that mind flayers often go in for. And of course seeing how the players react to such a town. Because on the one hand the people have a greater degree of both freedom and security than in most places but on the other hand they also get eaten once they're over the hill. It's the sort of situation that many of the people might feasibly choose especially if they grow up with it and are indoctrinated in it.

[MinotaurWarrior]

100 mind flayers eating 45 year Olds will require > 540 (bare sustenance) to 2160 (comfortable) people. To get the exact figure, you'll basically just add in enough to cover the mortality rate, by dividing by the survivorship rare. So if 10% of people die before reaching 45, that's going to be 540/0.9 = 600 people, minimum. Even at a more comfortable level of 2400 (mind flayers eating weekly) it's still a small town.

[dreast]

It's worth mentioning, in the context of this discussion, that mindflayer reproduction (at least, at the ceremorphosis point) is entirely a voluntary process. No mind flayer colony is going to outstrip its means of support, simply because they only make more mindflayers when they choose to. Tadpoles are regularly culled when they get too large, without any distaste at doing so (and may form part of that supplemental diet, in fact). So barring any external influence (like a gith raid), equilibrium will be naturally maintained between the host population and the mindflayer overlords (esp. given that mindflayers are "SUPER GENIUS" level intellects)(yes, that is a Wile E. Coyote reference). This doesn't answer the original question about population levels required for sustenance, but it does indicate that all else being equal, mind flayer growth doesn't have to be considered, which considerably simplifies the traditional predator/prey equations.

Also consider that too HIGH a population will result in the host population growing ever greater (exponentially), while the mind flayer colony sits in stasis, numbers-wise. This can be countered by, well, eating more, or making new mindflayers. But maintaining perfect stasis is probably untenable, and monitoring the level of population stability is probably a full-time job for a mindflayer or perhaps an underling.

[PhantomSoul]

This question really gives nice context for them spreading across the universe for illithidlets and munchies!

[fat.hampster]

100 mind flayers eating 45 year Olds will require > 540 (bare sustenance) to 2160 (comfortable) people. To get the exact figure, you'll basically just add in enough to cover the mortality rate, by dividing by the survivorship rare. So if 10% of people die before reaching 45, that's going to be 540/0.9 = 600 people, minimum. Even at a more comfortable level of 2400 (mind flayers eating weekly) it's still a small town.

Am I missing something, or have you forgotten to multiply by 100?

45 person-years / brain * 12 brains / year / mindflayer =540 persons/mindflayer.

Which would mean you'd need about a quarter of a million people for a hundred mindflayers to eat comfortably.

[MinotaurWarrior]

Am I missing something, or have you forgotten to multiply by 100?

45 person-years / brain * 12 brains / year / mindflayer =540 persons/mindflayer.

Which would mean you'd need about a quarter of a million people for a hundred mindflayers to eat comfortably.

Nope, you're 100% right. I forgot to multiply by 100.

[Eurus]

Am I missing something, or have you forgotten to multiply by 100?

45 person-years / brain * 12 brains / year / mindflayer =540 persons/mindflayer.

Which would mean you'd need about a quarter of a million people for a hundred mindflayers to eat comfortably.

Yeah, doing the math makes it pretty obvious that mind flayers don't take well to "brain agriculture" unless they've actually pulled off that empire thing and conquered the universe. It's certainly possible that there could be a city in the Underdark full of mortals who get preyed on by a ruling class of mind flayers, but it'd be hard to safely control that many people even with mind flayer psionics. So maybe you need half again that number of guards/soldiers who support the mind flayer status quo... it's going to be big, and it's going to be un-subtle, and it's probably going to be fragile.

Most of the depictions of illithids I've seen have them keeping some amount of slaves that they could use as emergency food in a pinch, but getting the majority of their food brains from raids on the surface and underdark. It's worth noting that there are plenty of non-human species that reproduce and mature faster than humans, but any way you slice it, you're going to be looking at a pretty huge operation.

[Sigreid]

Yeah, doing the math makes it pretty obvious that mind flayers don't take well to "brain agriculture" unless they've actually pulled off that empire thing and conquered the universe. It's certainly possible that there could be a city in the Underdark full of mortals who get preyed on by a ruling class of mind flayers, but it'd be hard to safely control that many people even with mind flayer psionics. So maybe you need half again that number of guards/soldiers who support the mind flayer status quo... it's going to be big, and it's going to be un-subtle, and it's probably going to be fragile.

Most of the depictions of illithids I've seen have them keeping some amount of slaves that they could use as emergency food in a pinch, but getting the majority of their food brains from raids on the surface and underdark.

Yeah, that's why I was thinking they would Logan's Run it. Be the secret overlords of a city of content humanoids completely unaware of their existance.

[Gtdead]

We will need some engineering involved to make this viable and efficient.

Let's assume that every woman will have one baby per year to avoid complications, and we won't calculate stillbirth and women dying in childbirth because I can't be arsed to do it.

Let's also assume that a woman is efficient from 12 to 35 to make numbers nice and easy. (I'm going to get flak for this, won't I? Hey, it's the mindflayers fault!)

We don't need couples, we just need women and a couple of men to impregnate them. Not too few though, cause we need hands for chores too.

The chance for the baby to be male or female is 50%.

So, we need 12 brains per year.
We basically need enough women to create enough surplus so in 12 years, there will be a new generation born that can continue the circle.

1 mindflayer needs 144 brains in 12 years, and
13 women can create 156 babies, a surplus of 12. Not enough
14 women can create 168 babies, a surplus of 24. Too many.

The answer is 13.2~ which creates a surplus of 14.4, enough babies to create a new generation of women and a man to impregnate them.
Sounds good. From there on, every woman you add is a bonus. A man will probably be able to impregnate hundreds of women, but I think one per 30 is the bare minimum. I'd go for 1 per 15 at least.

By the time the current generation will be 35 yo and make their last child, they can be eaten and the new generation is ready to start the circle anew.

So there you have it. We need a population of 14.2 per mindflayer, 13.2 women and 1 man to impregnate them.
Perfectly efficient, women won't be in a fighting condition so the only one that can be a problem is the man. He will need to be beaten regularly just to make sure he knows his place.

Be aware that probabilities suck, so if you are going to do this, you will need to start with more women just to be on the safe side. If you live in a society with many fellow mindflayers and you pool your resources it probably won't be a factor due to the law of large numbers

[Naanomi]

Using a race prone to multiple births or with faster gestation/pregnancy refraction probably helps a lot... goblinoids, gnomes maybe?

[Sigreid]

Using a race prone to multiple births or with faster gestation/pregnancy refraction probably helps a lot... goblinoids, gnomes maybe?

Kobolds by lore are supposed to mature in 10 years and be able to live to 120 or so, so their breeding age may be what, 40 years. And laying eggs probably has less death in birth.