Drow and math

[Pariah]

Alright, I'm trying to figure out if the Drow as written could survive.  Because huge math equations make me cry a little I decided that the best way to do this is brute force with perl.  So, after 6 hours writing a script I finally have something that doesn't suck, now it's onto finding actual numbers to base the estimates off of.

Where I'm at now:

Basing the Drow directly off of the Elf entry in the 3.5 SRD I have them living to age 300 (where they suffer a 100% mortality rate because I can't be bothered to make them older, they can't breed at that point anyway so it's moot.)  The SRD has Human middle age at 35 and Elven middle age at 175, a couple of fermi estimates later I get Human breeding age of 14.7 and a Elf one of 73.5.

Because Drow are Evil and kill each other like it's going out of style only half of all drow born will make it to the age of 74.  Because at this point I'm just doing raw estimates I'm going to give them a flat mortality rate of 0.932312147% a year.

Fertility wise I'm putting them at a birth rate that in humans would produce 1.9 children/family (6.33...%/yr).

What I found in this Extremely guessimate based simulation is that a mortality rate of 0.932312147% and a fertility rate of 6.3% gives them a stable population.

Now is where you all come in, I want any piece of information regarding Drow fertility and survival rates people can think of.  I've never read the Drizzt books, which I'm sure has something somewhere in them regarding how likely it is for Drow to reach adulthood, and when adulthood is for that matter.  Currently the only hard information I have comes from the Drow of the Underdark, pg 24.

The drow are notably more fertile than are their surface-dwelling cousins.  They become pregnant more easily and have a slightly shorter gestation period.

This information is less than helpful seeing as I haven't found any information regarding the rate of pregnancy in surface elves, nor their gestation period.

Perhaps spurred on by these hostile circumstances, drow children develop much faster than other elves -- almost as swiftly as humans, in fact -- often beginning schooling as early as age eight or ten.

This implies that drow reach adulthood sooner than elves, but it doesn't outright state it.

Once they have reached adolescence (at about age 20, by wich time over a thrid of them have been murdered or sacrificed.)

This is actually useful, kinda.  Adolescence implies the beginning of puberty.  In humans (F) puberty begins at 10-11 while (M) is 11-12 ending at (F) 15-17 // (M) 16-17.  For the sake of argument I'll just multiply all these numbers by 2 to get a guess for the Drow of 32 for sexual maturity.  Do they start having kids at this point is another question, though that one is extremely cultural and I doubt there's any information on it in the splatbooks.

On that note, I NEED INFORMATION!!!!!  Please

[valadaar]

This link appears well detailed,

http://drowcampaign.roleplaynexus.com/drowsociety.html

[Pariah]

And that looks like the best I'm getting.  I can find no real "official" information regarding the Drow, but most of that seems to be pulled from the DotUD book I quoted earlier, so now I have for information:

Children _at least_ once every hundred years, which sounds helpful until you realize the same could be said about humans.  On the other end you could say that Drow can have children at least once every other year and it'd be just as useless.  That's like trying to determine a human reproductive rate off of "Humans are capable of producing at least one and up to eight children every nine months.  While it is not a common practice, they've also been known to eat their young."

On their lifespan, "Drow live for several hundred years."  At this point I'm starting to hate the English language, which defines several as a number greater than two but less than many.  How much is 'many' you ask.  Why good sir, it is a large number of something...  FRACK!  Because Mrs Do'Urden lived to be 600 I'm just going to call that the new cap.

And now my own personal favorite: "Drow remain viable until the last few years."   Viable of doing what?  Left to the reader's imagination apparently, because it just goes on to say that if you're no longer viable you're gonna get kill.  I'm going to interpret this as negligible senescence, mainly because it gives the Drow the ability to keep producing more Drow until the point when they finally shuffle out of the simulation.

Stupid fantasy writers, stupid lack of scale.

[Pariah]

I decided to take a different tact.  I'm going to start with their surface dwelling kin.  AND I'm going to use numbers for a nominally first world country, the USA.

USA National Vital Statistics Report (May 8 2013)
Elves
Death Rate under 40: 0.01146% / year
Corresponding to ages 5-10 in Americans
Death Rate over 40: .11% / year
Corresponding to ages 30-35 in Americans
It also corresponds to an Elven half-life of around 629.75 years.  Because I'm lazy and don't want to go through the effort of changing code too much, I'm just going to continue saying that everyone dies at the age of 600, just like their Drowish cousins.

Because the surface elves are a peace loving peoples, and have access to modern healing magic, I feel like these numbers shouldn't be that far off, as far as that goes.

All the numbers correlate to a starting population of 1000 elves, over 1000 years.


Birth Rate: 0.5% chance / year
1751 1673
1619 1603
1666 1678
1420 1683
1969 1551

0.0662% annual growth rate

Birth Rate: 1%
24325 22248
22296 22202
21896 21284
19484 21538
22549 23780

2.1181% annual growth rate

So assuming the yearly fatality rates are accurate, Elven birth rates are most likely closer .5% chance a year, seeing as a 2.11 growth rate is about the same as Sudan and a couple other high growth rate 3rd world nations.  It also jives with the description of the Elven race as a kin to pandas, namely not willing to screw to save their species.

[Pariah]

I think I finally figured it out.  Violent crime rates, assuming every violent crime corresponds to a Drow dying.

Detroit, Michigan - 2,122.9 per 100,000 (#1 in the nation)
Buffalo, New York - 1,288.7 per 100,000 (#10 in the nation)
Minneapolis, Minnesota - 992.2 per 100,000 (#20 in the nation)
Wichita, Kansas - 742.5 per 100,000 (#30 in the nation)
Phoenix, Arizona  - 636.7 per 100,000 (#40 in the nation)

Convert all of them to a death rate we get 2.1229% / year under the age of 20, which gives us 65% surviving to the age of 20.  The next 20 years you face a 1.2887% chance of dying a year, so on and so forth.  A falling death rate as you get older and more able to play the "I'm a murderous Drow" game.  With every age grouping being twice as long as the one before it the Drow should only need to have a kid once every 33 years for as long as they're still alive.  Testing is needed, but will be done tomorrow.

[Pariah]

Actually I couldn't sleep.  Current vital statistics:

$ChildDeath =  .978771; #You chance, each year, of living to see your next birthday.
$TeenDeath =   .987113;
$AdultDeath =  .990078;
$MiddleAgeDeath = .992575;
$SenescenceDeath = .993633; #half-life of ~108.5 years.
$SexRatio =    .5; #chance of being female.
$BirthRate =   .036; #your chance, each year of having a brat.
$StartingPopulation = 1000;
$EndifUnder = 1;
$EndifOver = 32000;

and running it 10 times for either 10,000 years, or until the population reaches one of the set points gives us this:

Year: 29167
Total Population: 32039
Growth Rate: 0.106418212363287%
Year: 26391
Total Population: 32003
Growth Rate: 0.117475654579213%
Year: 31760
Total Population: 32006
Growth Rate: 0.0976259445843829%
Year: 40867
Total Population: 32039
Growth Rate: 0.0759512565150366%
Year: 30601
Total Population: 32008
Growth Rate: 0.101330021894709%
Year: 27090
Total Population: 32014
Growth Rate: 0.114485049833887%
Year: 29421
Total Population: 32001
Growth Rate: 0.105370313721491%
Year: 36650
Total Population: 32002
Growth Rate: 0.0845893587994543%
Year: 34917
Total Population: 32013
Growth Rate: 0.0888191998167082%
Year: 29355
Total Population: 32014
Growth Rate: 0.1056515074093%

So yeah, assuming your chances of dying each year as a Drow are about the same as being mugged in Detroit, Buffalo, Minneapolis, Wichita, and Phoenix and you have a kid once every 28 years on average, you can have a sustainable population.

[Gossamer]

I didn't think I could add much to this because it was a while since I read the books. But you can't cap the life-span at 600. At least not the natural one.


http://forgottenrealms.wikia.com/wiki/Yvonnel_Baenre

Matron Baenre had lost much of the beauty she possessed while young to a combination of factors, including several uses of zin-carla. At the end of her life she looked haggard, with a patchwork of wrinkles across her face. Possessing an unusual vibrancy she was capable of pregnancy till her late 1900s.

She lived to be 2043yrs old, and she only died because she was killed.

http://forgottenrealms.wikia.com/wiki/Drow

Drow have lifespans far beyond that of humans and comparable with the rest of the elves, although usually somewhat longer. This is, of course, presuming the drow doesn't meet a premature and violent end, as many often do, but those that survive the trials of their society and the horrors of the Underdark can live for centuries,[3] sometimes as long as 1000 years or more.

[Pariah]

Grrrr.....   I could add another 400 years onto the end of the end of the code, but the only thing that really matters for the sake of the survival of the Drow as a species in this case is actually when they are no longer able to breed.  Even assuming they can breed until the age of 3,000 I'm still only losing 2.3900306% of the populace by cutting it at 600.

Continuing it until the age of 1000 gives us a survival rate of 0.1856975% and IF I continued the simulation out to the age of 2000 about 0.0003125% of the Drow populace would survive to be shuffled of the script do to my laziness.

[Pariah]

And after writing all that and then clicking the link of one child of Mrs Baenre, I'm going to have to do just that.

Berg'inyon Baenre (alternately spelt Bergynion), the youngest son to Yvonnel ... He is Drizzt Do'Urden's rival in the academy

It's not kind enough to give us a death date, but Drizzt was born in 1297 DR, while Yvonnel was born in -685 DR.  Assuming her son is within 10 years of Drizzt age wise, that means she was fertile up until the end...  1400 more years of Drowdom, here I come.

[Pariah]

Having added the next 1400 years to the simulation we get the following numbers.  I'm currently running 3.5% after doing 3.6, and I really feel like there should be an equation for these kinds of things.  Most of the stuff I found for figuring out the demographics of a fantasy species was basically "Well, you take the idealized demographics I made up on the spot for Middle Ages type populations (or possibly based off of the Doomsday Book) and then just directly correlate them to your fantasy race, adjusting for stuff."  At this point I'm positive I'm putting too much effort into this, but I no longer care.  I /WILL/ figure out how often the Drow need to have babies.  Then I'll work on kobolds.  Or goblins.  Or some other race that lives less than 100 years.

Year: 59260
Total Population: 32004
Aged Out: 54
Growth Rate: 0.0523185960175498
Year: 50555
Total Population: 32020
Aged Out: 28
Growth Rate: 0.0613589160320443
Year: 40523
Total Population: 32007
Aged Out: 31
Growth Rate: 0.0765170397058461
Year: 51986
Total Population: 32021
Aged Out: 36
Growth Rate: 0.0596718347247336
Year: 38186
Total Population: 32026
Aged Out: 27
Growth Rate: 0.0812496726548997
Year: 48209
Total Population: 32017
Aged Out: 40
Growth Rate: 0.0643386089734282
Year: 49310
Total Population: 32009
Aged Out: 39
Growth Rate: 0.0628858243763942
Year: 73672
Total Population: 32000
Aged Out: 41
Growth Rate: 0.0420784015636877
Year: 40103
Total Population: 32019
Aged Out: 42
Growth Rate: 0.0773483280552577
Year: 56638
Total Population: 32009
Aged Out: 25
Growth Rate: 0.0547494614922843

Year: 16251
Total Population: 32012
Aged Out: 11
Growth Rate: 0.190831333456403
Year: 14788
Total Population: 32008
Aged Out: 6
Growth Rate: 0.209683527184203
Year: 16167
Total Population: 32005
Aged Out: 9
Growth Rate: 0.191779550937094
Year: 12379
Total Population: 32007
Aged Out: 7
Growth Rate: 0.250480652718313
Year: 13425
Total Population: 32000
Aged Out: 3
Growth Rate: 0.230912476722533
Year: 15378
Total Population: 32008
Aged Out: 10
Growth Rate: 0.201638704642996
Year: 13094
Total Population: 32070
Aged Out: 5
Growth Rate: 0.237284252329311
Year: 14898
Total Population: 32019
Aged Out: 8
Growth Rate: 0.208209155591355
Year: 13905
Total Population: 32010
Aged Out: 11
Growth Rate: 0.223013304566703
Year: 13381
Total Population: 32000
Aged Out: 5
Growth Rate: 0.231671773410059

Year: 8494
Total Population: 32025
Aged Out: 4
Growth Rate: 0.365257829055804
Year: 9242
Total Population: 32013
Aged Out: 7
Growth Rate: 0.335565894827959
Year: 8315
Total Population: 32032
Aged Out: 3
Growth Rate: 0.373205051112447
Year: 7894
Total Population: 32003
Aged Out: 2
Growth Rate: 0.392741322523436
Year: 7468
Total Population: 32040
Aged Out: 3
Growth Rate: 0.415640064274237
Year: 7918
Total Population: 32001
Aged Out: 2
Growth Rate: 0.39152563778732
Year: 7967
Total Population: 32039
Aged Out: 2
Growth Rate: 0.389594577632735
Year: 7925
Total Population: 32005
Aged Out: 6
Growth Rate: 0.391230283911672
Year: 8233
Total Population: 32036
Aged Out: 3
Growth Rate: 0.37697072755982

[Pariah]

Ran into this: http://www.gf9.com/hobby.aspx?art_id=3660 when I was looking into whether or not Drow are known for all out civil war or if they just rely on their constant state of cold war to keep their population in check and I decided that since I now have a way to actually test their statement, I might as well give it a go.  In this run through, the birth rate is 3.5% and any Drow over the age of 140 has a .11% chance a year of dying.

Year: 1259
Total Population: 32106
Aged Out: 0
Growth Rate: 2.47069102462272
Year: 1223
Total Population: 32079
Aged Out: 0
Growth Rate: 2.54121013900245
Year: 1198
Total Population: 32083
Aged Out: 0
Growth Rate: 2.59457429048414
Year: 1203
Total Population: 32045
Aged Out: 0
Growth Rate: 2.58063175394846
Year: 1223
Total Population: 32034
Aged Out: 0
Growth Rate: 2.53753066230581
Year: 1248
Total Population: 32010
Aged Out: 0
Growth Rate: 2.48477564102564
Year: 1260
Total Population: 32025
Aged Out: 0
Growth Rate: 2.46230158730159
Year: 1228
Total Population: 32092
Aged Out: 0
Growth Rate: 2.53192182410423
Year: 1215
Total Population: 32002
Aged Out: 0
Growth Rate: 2.5516049382716
Year: 1223
Total Population: 32065
Aged Out: 0
Growth Rate: 2.54006541291905

And the answer is yes.  With a 2.5% annual growth rate, the rule of 72 gives us ~29 years between population doublings.  A century of relative peace would octuple the Drow population.  Granted almost all of that growth would be under the age of 120, and it'd be such a shame losing so many so young in the bloodiest Surface-Underdark war in history...  Who am I kidding, it'd be a freaking barrel of laughs.    I feel like there's an adventure in there.  The spymaster for the Elven nation of Green-trees-and-flowers approaches the party, "Our dark cousins have been acting funny.  For the past 30 years or so there's been maybe a tenth of the wanton slaughter that we normally associate with them.  Could you, you know, go check it out?  I mean, it'd be nice to think that they've finally started abandoning their evil ways, but the fact that they still seem to be worshipping Lloth tends to imply otherwise..."  At which point the party would only need to fight an entire nation composed of level 1-3 fighters, wizards, and clerics.

And back to searching.

[Murometz]

God bless you, Pariah. You're an original.

[Pariah]

Pariah: I just felt you should know that, because I love you like a genderless sibling
Gossamer: I'm not genderless, I'm just not telling, there's a big difference. Don't you have some math problem to occupy yourself with instead? Calculating how much grain elves eat or something?
Pariah: I would assume it's roughly equivilent to the amount of grain eaten by the average sentient, at least when they're in lands where grain production is common
Pariah: presumably they subsist on twigs and leaves in their natural habitat
Pariah: also, just because I'm feeling particularly pedantic this particular morning, I shall deign to point out that in my previous comment I said "like a" instead of "as a" which tends to imply that I was merely comparing you to something without a gender rather than stating you were without a gender
Gossamer: How is that any better? Groovy tune though.
Pariah: though figuring out how many acres of mushrooms it would take to feed a single Drow would possible help put an upper limit on optimal Drow population size
Gossamer: I don't think mushrooms are a very good staple food, but then again not my area of expertize.
Chaosmark: In the end, it's a matter of calories. Nutrition can be handwaved, because they would've evolved to survive on what the mushrooms provide.
Pariah: Because in one of the options I don't really care, in the other I'd currently be fantisizing about the most efficient way to remove the spinal cord from a genderless pedant prior to inserting it forcefully through the sphincter of said cur. Of course, because I love you like a genderless sibling it's the first and not the second.
Pariah: and we definately need a crazy person grin for the small chat...
Gossamer: If you eat too much mushrooms though, don't you get indigestion? Evolution is kinda hard to apply to sentient beings since they'd be smart enough to stop eating if it didn't do them any good.
Pariah: I don't think you'd get indigestion from eating too many shrooms
Pariah: also if that was a problem cooking and or fermentation would likely deal with it
Gossamer: my spinal cord, whaa?
Pariah: Fermented Shroom Curds, a delicacy
Pariah: oh, good catch, I meant column
Pariah: I'd want to use the whole assembly and not just the nerves
Chaosmark: A quick google search says you need a truly ridiculous quantity of mushrooms for sufficient caloric intake. The highest that google lists is 81 calories for 1 cup of shtake. Most are significantly lower (10-20).
Chaosmark: Compared to, say, wheat, which is 600+ calories per cup.
Gossamer: You're a weird one P. One bad day away from going postal... O.o
Chaosmark: And meat, which is ~200 calories.
Gossamer: maybe they're fatty shrooms
valadaar: hm, they seem mostly water.
Chaosmark: Whatever handwaving you wish to do, be my guest. I'm just providing raw numbers to let you know what answers you need to come up with.
Pariah: namely really really painful ones
Gossamer: Well I wasn't really looking for an answer, it just turned out that way.
Gossamer: Insects would probably be a good source underground though?
Pariah: the only reason I like dealing with "how do the Drow survive" questions is because they're basically living in fantasy arcologies already
valadaar: Dried they are pretty good
Pariah: yeah, probably have to move over to using a diet of insects, shrooms, and some sort of blue-green algae for drow diet
valadaar: [link]
valadaar: 75% carb, 10% protein.
valadaar: though you'd need a lot of em in any case.
Pariah: Actually that's not all that far behind wheat once you dry it
Pariah: both are at about 330cal/100g
Pariah: extremely low fat through
Pariah: they'd need to get that from somewhere, otherwise the entire drow race would die off of rabbit starvation
valadaar: thats what grubs are for
valadaar: the nice big, fat, white ones.
Pariah: dead slaves too
valadaar: no, they'd be skinny as hell
Gossamer: [link]
valadaar: freshly captured halflings.
Pariah: yeah, but the human slaves will likely die with about 2-7% body fat, depending on gender, which goes up once you start cutting out the weight of the skeleton and the guts
Pariah: it wouldn't be enough to keep the general populace from dying, but it'd definately serve to supplement the diet of the aristos
valadaar: Have to take into account the dangers of eating such closely related food - being so long lived, not sure they would play around with prions.
Gossamer: There are quite a few humanoids in the underdark, a few of them barely sentient. So that, and a bit of cannibalism on the side.
valadaar: "Fat is the other major component of most insects with raw, whole insects ranging from a low of 2.2% for Nasuititermes corniger (Motschulsky) worker termites, to a high of 60% for greater wax moth, Galleria mellonella (L.) larvae. "
Pariah: very good find val, I didn't know they could go that high
valadaar: I'd say bugs would be the saner route.
Pariah: so yeah, bugs definately saner
Pariah: easier to raise in captivity, quickly reach a point where they can be eaten
valadaar: [link]
Gossamer: Termites and moths only live on the surface though? That far down, earthworms and what not seems more likely.
Pariah: less likely to start revolts
valadaar: those are just examples that bugs can be fatty
valadaar: giant subterainian bugs could easly lean towards the fatty.
Gossamer: Umberhulks, Purple Worms.
Pariah: and it's likely that with 2000 year life expectancies or whatever it ended up being in the DnD world, Drow with an interest in controlled breeding to make a species of feed moth would have plenty of time to select for the traits of "willing to eat dirt" and "doesn't mind there being no sun"
Pariah: the problem with relying on large game for food is that it's primarily a supplement rather than a reliable source
Gossamer: Who would go through that kind of trouble just to eat moths? They would just taste like dust or something.
Gossamer: Also they're hairy. Brr...
Pariah: If my options are moth grubs and a slow and painful death I'll go with the grubs :/
Pariah: sure the back of my throat is making those involentary contractions, but I'm pretty sure I could grind them and use them in a stew or something
Pariah: possibly a porridge
valadaar: probably breed out the hairs
Gossamer: I don't think the decadent drow would live a life of barely subsisting though. Sooner they'd summon in food with magic.
valadaar: Big, living sausage like bugs that stay grubs for their entire lives
valadaar: even if they once were motjhs
Pariah: sure the decadent drow might summon food, but what about the 95% of their population that is lvl 1?
valadaar: so kind of like 6-legged pigs
Pariah: ^yes!^
valadaar: any bigger and they are hard to handle.
valadaar: smaller, and too much gut to food ratio,
Gossamer: The lvl 1s would buy from the 5%?
Pariah: psh, dealing with commoners?
valadaar: and _they_ eat the slaves
Pariah: what Drow matriarch (or wanna be matriarch) would stoop to that level
Gossamer: I think it did say that they had like some kind of insects that were big as cows.
valadaar: as well as anything punted into their sty's
valadaar: I wouldn't want a cow-sized pig
Pariah: I barely like pig sized pigs
Pariah: those things can be kinda annoying when they decide to
Pariah: and downright homicidal on occasion
Gossamer: I have the Menzoberranzan : City of Intrigue book right here, 4e ed. *arhm*
valadaar: well, 4ed has no credibility
Gossamer: yes it does, shush.
valadaar: Nope Nope Nope Nope ... oo 5th looks pretty good though
valadaar:
Pariah: that and the entire backstory of faerun was cobbled together based off of "this sounds neat" while I'm trying to find if it could actually work as written or not
Gossamer: Oh right, they were called Rothé
Pariah: I actually haven't looked into 5e at all yet
valadaar: Its not bad. I kind of like some of the simplifications.
Pariah: Rothe appear to be cave cows, no where near as flavorful
valadaar: I like the sausage-catapillers better. Weren't those the Stench Kows?
Pariah: [link]
Gossamer: "Closely related to the cattle of the same name herded by surface-dwelling ranchers throughout the North, deep rothé are Underdark herd animals that stand three to four feet tall at the shoulder. Unlike their surface-grazing cousins, deep rothé have the abbility to conjure magical light that they use to communicate simple concepts within a herd."
Gossamer: Drow are fond of deep rothé meat, which many maintain to be more tender and less gamey than that of surface cattle.
Chaosmark: Because light-based morse code totally makes more sense than, say, subsonic vibrations or pheremone-based communication.
valadaar: "Hey monsters, come eat me!"
Pariah: like I said, it sounds neat
Chaosmark: ^
Gossamer: Hehehe, yeah they can't have been doing very well in the wild.
valadaar: that would last like 1 generation.
Gossamer: Donigarten's western shore yields moss eaten by noble drow as a delicacy. North of the lake stands a grove of giant edible mushrooms, carefully cultivated by drow horticulturists.
valadaar: or, they don't simply eat their 'livestock', they embrace their arachnidic tendencies and 'bleed' them, yeilding a thick blue
valadaar: 'milk'
Gossamer: Donigarten is surrounded by vast fields of tilled earth worked by orc farmers. Slaves pour water into carefully irrigated dung fields, renewing and expanding the fields with wagonloads of excrement brought in from the city proper. The soil is moist and rich in nutrients, making it excellent food for the countless varieties of moss, algae, mold, fungi and lichen that thrive in that enviroment.
valadaar: which is then used in dozens of ways - akin to dairy.
Gossamer: oooh I like that! Like bats.
Pariah: with enough breeding and/or magic you could make the grubs functionally immortal
Pariah: like that one kind of jelly fish that rather than dying returns to a polyp
valadaar: Drow milkmaids would carry grim instruments appropriate for the task.
valadaar: masks to keep from being spattered, etc.
Gossamer: That's a sub right there, Drow Milkmaids.
Pariah: but that takes away the easy source of black leather that all drow are required by some artist bylaw to wear
valadaar: Dont make em immortal.
Pariah: right, just use the meat and skin upon death
valadaar: they wear out.
valadaar: Also, dedicated slaved to hold the wiggly buggers down for the extraction.

Possibly figure out how much of a drow settlement needs to be devoted to agriculture.

[valadaar]

some numbers, from random internet resources. Good for RPG background though:

"One hundred pounds of feed produces 10 pounds of beef. The same amount of feed would produce more than four times that amount in crickets [source: National Geographic]."

So, 40% Feed to Bug ratio.

Lets feed 'em mushrooms

"Oyster mushrooms also produce heavy yields – the average is one pound of mushrooms for each pound of straw used to grow them. Most commercial growers average six “crop cycles” per year. This allows growers to produce lots of mushrooms in a small space. A 200 square foot growing area, for example, can produce 6,000 pounds of mushrooms each year!"

Mushrooms are mostly water, so lets say we get 2000 lbs of dried mushrooms for 200 square feet.  No fat though. So we feed this to the bugs, and get 800 lbs of bug for food. enough to feed 3-4 smallish beings like drow.


Ok, we need to give them some form of food to start with.   Where are they going to get the stuff to feed the mushrooms?  Some can be recycled waste products, but you need net new organics into the system.  .. Well, dead enemies could certainly make up some of the difference, but other forage is going to be necessary.  In any case, I expect the drow to be very frugal with their resources, and take great care not to waste anything.

I think we agree that restricted to real-world resources, an underground ecology would be very boring and slow, so we should assume that there are lifeforms in the underdark that we don't have.  Perhaps other mushrooms not directly edible, and slow growing, are gathered by foraging parties.  Straw/etc, is traded/stolen/tributed from surface races to supplement the foraging underground.