How Many Dragons Could Live on Earth?

[Mr. Mask]

Have you ever asked yourself, "I wonder how many theoretical dragons could sustain themselves across a planet of similar qualities to this earth we live on?" You're here... so of course you have!

The calorie intake will vary based on the size of the dragon. Let's say approximately five tons, about the size of the late tyrannosaurus rex. The dragons, of course, are presumed to fly.


Late last night I calculated something like 60,000 calories daily, but I think I was too sleep deprived when I ran the math. Still, if that's accurate, you could probably have a larger number of dragons than some might expect (presuming they become apex predators). I couldn't be bothered to work out how wide the feeding territory would need to be over land habitats or sea to get that quantity, since the number might be bogus to begin with.

[Wombatant]

Have you ever asked yourself, "I wonder how many theoretical dragons could sustain themselves across a planet of similar qualities to this earth we live on?" You're here... so of course you have!

The calorie intake will vary based on the size of the dragon. Let's say approximately five tons, about the size of the late tyrannosaurus rex. The dragons, of course, are presumed to fly.


Late last night I calculated something like 60,000 calories daily, but I think I was too sleep deprived when I ran the math. Still, if that's accurate, you could probably have a larger number of dragons than some might expect (presuming they become apex predators). I couldn't be bothered to work out how wide the feeding territory would need to be over land habitats or sea to get that quantity, since the number might be bogus to begin with.

Very interesting to think about. Dragons have also been known to sleep for long periods of time. Maybe cycles would occur, where much of the livestock would be depleted, only to have a 'period of peace' where they would regenerate while the dragons slept/hibernated?

I assume it would be a terrible place to live, unless the dragons were friendly/sentient haha

Edit: Average human of - lets say, 180lb has a 2000 calorie per day intake. thats 11 calories per pound. If a dragon weighs 5 tons, thats 5280lb per ton, so 26,400lb.

26,400lb * 11 calories per pound = 290,400 calories. :0

[Eldan]

We'd have to answer some questions on dragon biology first. Are they endothermic? Can they fly? How about fire?

That would change a lot of things massively. If we give them the metabolism of, say, a large crocodile or komodo dragon, the requiremens would be much lower than if we modelled them as, say, something like a carnivorous elephant.

[Wombatant]

We'd have to answer some questions on dragon biology first. Are they endothermic? Can they fly? How about fire?

That would change a lot of things massively. If we give them the metabolism of, say, a large crocodile or komodo dragon, the requiremens would be much lower than if we modelled them as, say, something like a carnivorous elephant.

I agree, my basis on human caloric intake is rather un-scientific, but so is this whole thread. :D

[factotum]

XKCD did a similar thought experiment based on a T-Rex:

http://what-if.xkcd.com/78/

Of course, dragons fly and breathe fire, which makes calculating their required calorie intake somewhat more problematic! (I think it's pretty much guaranteed that they can't have a reptilian metabolism given what they're portrayed as being capable of, though).

[Mr. Mask]

We'd have to answer some questions on dragon biology first. Are they endothermic? Can they fly? How about fire?

That would change a lot of things massively. If we give them the metabolism of, say, a large crocodile or komodo dragon, the requiremens would be much lower than if we modelled them as, say, something like a carnivorous elephant. A dragon that can't fly and breathe fire is no dragon! Admittedly, if they can breathe fire and are reasonably fireproof, that might settle any shortcomings of being ectothermic.

Did a quick search, and found this site: http://www.world-builders.org/lessons/less/biomes/annutrita.html

Based off those calculations, a 10,000 pound dragon would need 25,200 calories per day if it were ectothermic, or 171,900 if they were like passerine birds. I figure on some middle-ground between the two.



Assuming that's a decent range, it still leaves the question of how to calculate the extent of each dragon's hunting ground, how much land they need to provide the necessary calories. I'm pretty sure there was some formula for that. Since dragons can fly and are supreme predators, it simplifies the problems predators normally face in catching prey, and they're able to prey on other predators (thus protecting their herbivore food source from competition).

[Pokonic]

If we go with DnD Red Dragons as a physical base, no magic or intelligence involved, I would think that's the base basis for this.

[Jay R]

Another possible limitation was best explained in The Voyage of the Dawn Treader:


And there is nothing a dragon likes so well as fresh dragon. That is why you so seldom find more than one dragon in the same county.

[Mr. Mask]

That would encourage them to spread out and to not infringe on others' territories.


Looking at the gray wolf population of Canada, there are approximately 50,000 wolves. Their intake is roughly 15,000 calories daily. If we assumed a calorie intake of 100,000 a day for dragons, there could be 7,500 Dragons in Canada alone.

This of course isn't taking into account other factors. As mentioned, dragons can prey on anything they can find, and finding and catching your prey is easy when you can fly. They can turn the wolves into a food source, increasing the potential number of dragons as wolf populations lower, deer and other prey populations increase, and prey options widen (since they can eat bears, wolves, etc.).

This is just the numbers based off wolf populations, so the actual number of dragons could be said to be exceptionally greater than 10,000, within Canada alone. Deer populations in North America are in some places heavily overpopulated, which shows that predator calorie intake and population isn't enough to show the potential for dragons. Combined breeding rates of all potential prey creatures (pretty much all of them, unless you figure humans and domestic animals will have a sort of truce with dragons) with their calculated calorie value could be used for an estimate of dragons' sustainable population (of course, in reality, dragons would likely over populate and overeat, causing problems when there isn't enough prey to go around). Remember that many kinds of fish are likely on the menu, if dragons can be presumed able divers or even swimmers (dragons sometimes have strong connections with water).

[Metahuman1]

Assuming they can breath fire, you'd need to take into account if they have anything they specifically need in order to accomplish that.

There was a discovery channel special that stated that they needed to be able to munch Platinum for there fire to work, or an old Animated Movie, Flight of Dragons, that stated they needed a combo of limestone and a harder stone (preferably Gemstones.) to go in with the lime stone to grind it up so that it could be digested so that it could produce gas to help fuel both fire and flight.


Would need to know if this is a factor or not.



Another thing to consider is, is there a domesticated version (Assuming there not sentient of course.), as that changes the game up to a point as well.

[Mr. Mask]

While that's interesting in relation to legends of dragons eating gemstones, I think they were exaggerating. Bombardier beetles use fire, purely through chemical reaction. There are various natural chemicals and gasses which do work well for fire creation, though certain diets could be helpful for this.

If the dragons needed gemstones to breathe fire, particularly if they needed large quantities over their lifetime, it would be safe to say that fire-breathers would be rare among dragons. Limestone and other rocks would be easier, still necessitating dragons to make trips to suitable deposits (possibly making for communal meeting places).

If there were domestic dragons, their population would be based off human need and economics. They might cause problems for wild dragon populations.

[Metahuman1]

In the second setting, Gemstones were preferred, but I imagine any sufficiently hard stone would do. Granet or Marble for instance are both to my knowledge harder and heavier then Limestone. (Not a geologist so don't quote me here.)

[Eldan]

On fire, let's do some basic calculations.

On Wikipedia, I found data on some WWII flamethrowers.

An M2, the American flamethrower of choice, uses half a gallon of gasoline per second and, for a flamethrower, has a relatively short range of 20-40m. Seems fitting.

Gasoline contains 120 MJ/US gal.

So, if a dragon is comparable to a WWII flamethrower, a two second blast of fire uses 120MJ. Which is about 29 million calories, i.e. 29000 kilo calories.

Top beef is about 300 calories per 100 g, so our theoretical dragon would need... about ten kilos of meat for two seconds of fire.

[leafman]

Very interesting to think about. Dragons have also been known to sleep for long periods of time. Maybe cycles would occur, where much of the livestock would be depleted, only to have a 'period of peace' where they would regenerate while the dragons slept/hibernated?

I assume it would be a terrible place to live, unless the dragons were friendly/sentient haha

Edit: Average human of - lets say, 180lb has a 2000 calorie per day intake. thats 11 calories per pound. If a dragon weighs 5 tons, thats 5280lb per ton, so 26,400lb.

26,400lb * 11 calories per pound = 290,400 calories. :0

Your math is off, there are only 2000 pounds in a ton (2200 in a metric ton). So, it would be 110,000 calories.

What would be our theoretical environment for the dragons? Tropics? Desert? I can't see them doing well in colder climates due to not having fur or feathers for insulation.

[Jeff the Green]

While that's interesting in relation to legends of dragons eating gemstones, I think they were exaggerating. Bombardier beetles use fire, purely through chemical reaction. There are various natural chemicals and gasses which do work well for fire creation, though certain diets could be helpful for this.

Caribdids (a group of insects containing bombardier beetles) don't produce fire, just very hot (near boiling) liquid. If that's good enough for you, it's probably scalable, but a gout of fire it ain't.


I can't see them doing well in colder climates due to not having fur or feathers for insulation.
You'd be surprised. Because of the square-cube law dragons might have trouble shedding extra heat. Particularly if they're active hunters, smart, or fly often, which would imply endothermy.

This article (http://deepseanews.com/2013/07/kaiju/) is possibly relevant. Apparently kaiju are related to dinosaurs and they're about the right size, so the calculations are probably similar for dragons. It estimates around 150,000 kilocalories (the Calories you see on packaging) per day, or around 12 people.

[Mr. Mask]

Meta: Dragons might need to be intelligent to work out gemstones are preferable. That, or they'd need some complicated instinct, which might cause them to swallow anything hard (including glass).


Eldan: Was figuring on methane-based gas, myself. Not sure how well a biological lifeforms could synthesize something like the mixture used in flamethrowers--it might make the calorie requirements even worse.


Jeff: True. The bombardier still seems a good example of chemical reactions in creatures, I guess.



I remember someone on the forums coming up with a formula for working out the feeding potential of an area. It was in one of the Weapon and Armour thread in the past, that someone worked out how many dragons there might be. It seems unfortunately none of us are familiar with the system used for working out an estimate of this.

[Jeff the Green]

I remember someone on the forums coming up with a formula for working out the feeding potential of an area. It was in one of the Weapon and Armour thread in the past, that someone worked out how many dragons there might be. It seems unfortunately none of us are familiar with the system used for working out an estimate of this.

I'm skeptical of this. It's not the particular subfield of ecology I've studied, but there are so many variables I'm not sure you could get any more out of such an attempt than tiredly saying "no, a viable population of large primates could not survive in the areas of the Pacific Northwest that are uninhabited" while rolling your eyes. You'd have to deal with specific species of prey available, their caloric value, their r and K (http://en.m.wikipedia.org/wiki/R/K_selection_theory), migration patterns, and probably a number of other factors.

[Cikomyr]

It has been theorized that human ended up cooking their food to process it more easily, so it's more energy-efficient. Maybe dragons do the same? they derive more energy from the meat they eat through cooking it, but it's only because they end up needing so much of it?

[Wombatant]

... I just realized i used feet in a mile instead of pounds in a ton. Doh. 5280 FEET = 1 mile.... haha! It was late. :D So, 110,000 calories based on the simple 'human diet' caloric intake model.

[Mando Knight]

If we go with DnD Red Dragons as a physical base, no magic or intelligence involved, I would think that's the base basis for this.

How old? The toddler-dragons are the size of a human, the big ones (tail and all) are huge, as big as fighter jets (4e's Draconomicon puts Ancient Reds at the same length as an F-22 at ~62 feet, but then compared to the fighter's maximum takeoff weight of 83500 lbs, the Red might weigh up to 165000 lbs)... using the same stats, it's also bigger than a sperm whale, as well as basically all known predatory dinosaurs.

Not as big as a blue whale, though, those are ridiculously huge.

... I just realized i used feet in a mile instead of pounds in a ton. Doh. 5280 FEET = 1 mile.... haha! It was late. :D So, 110,000 calories based on the simple 'human diet' caloric intake model.
So... the simple "human diet" is a simple human diet: about one human a day, according to Ryan North of Dinosaur Comics. (http://www.topatoco.com/merchant.mvc?Screen=PROD&Store_Code=TO&Product_Code=QW-PERSON&Category_Code=QW)

[Jeff the Green]

It has been theorized that human ended up cooking their food to process it more easily, so it's more energy-efficient. Maybe dragons do the same? they derive more energy from the meat they eat through cooking it, but it's only because they end up needing so much of it?

The question is how much it increases net calories. It costs very little energy for a human to make a cooking fire. If we had to synthesize the fuel and enzymes to ignite it we'd all be eating sashimi and carpaccio.

[Eldan]

Eldan: Was figuring on methane-based gas, myself. Not sure how well a biological lifeforms could synthesize something like the mixture used in flamethrowers--it might make the calorie requirements even worse.

They probably could synthesize something very close to gasoline. Various medium-sized hydrocarbons, at least. But yeah, my calculation was a best-case scenario, and not a likely one.

How about hydrogen instead of methane? It can be biosynthesized and it makes a pretty damn amazing fuel.

[Mr. Mask]

Eldan: A gasoline/Greek-fire spitting dragon would be pretty terrifying, I must say.

I'd have no problem with hydrogen based fire for dragons. People often comment about using hydrogen to aid dragons with flying, come to think of it.

[Eldan]

Though now I'm wondering how difficult the gasoline would actually be to ignite. You need correct mixtures. Maybe aerosolize it first? Spit out a cloud, then ignite it with something like the bombardier beetle reaction?

[Brother Oni]

There was a discovery channel special that stated that they needed to be able to munch Platinum for there fire to work, or an old Animated Movie, Flight of Dragons, that stated they needed a combo of limestone and a harder stone (preferably Gemstones.) to go in with the lime stone to grind it up so that it could be digested so that it could produce gas to help fuel both fire and flight.

The chemistry was mixing limestone (calcium carbonate) with stomach acid (hydrochloric acid), using various handwaved metabolic pathways to effectively react elemental calcium with HCl to produce hydrogen and calcium chloride.
The grinding is to increase the surface area of the limestone to improve the reaction rate.
In reality, the liberated oxygen from the carbonate would mop up any freed hydrogen, resulting in carbon dioxide, water and calcium chloride (if you want to get picky, you have an intermediate of carbonic acid which decomposes to water and carbon dioxide).

A hydrogen bioreactor would be much more effective, but given that such naturally occuring systems require sunlight, we're looking at a semi-translucent photosynthetic dragon.


Gasoline contains 120 MJ/US gal.

So, if a dragon is comparable to a WWII flamethrower, a two second blast of fire uses 120MJ. Which is about 29 million calories, i.e. 29000 kilo calories.

Top beef is about 300 calories per 100 g, so our theoretical dragon would need... about ten kilos of meat for two seconds of fire.

Even assuming the biosynthesis of petrol was possible, this isn't really a very good way of estimating energy cost. We manufacture ~7.5g of HCl a day (~2 litres of 0.1M) in our stomach - depending on the process, inorganic synthesis of HCl can require temperatures of 2000+C, which is well above our daily metabolic requirements.


Though now I'm wondering how difficult the gasoline would actually be to ignite. You need correct mixtures. Maybe aerosolize it first? Spit out a cloud, then ignite it with something like the bombardier beetle reaction?

If we're using gasoline, the autoignition temperature is between 246-280C and achieving a fine spray would be required. In the case of hydrogen, we're looking at 536C.

The bombardier beetle's reaction simply doesn't get hot enough to achieve these temperatures. Ignition could be performed by using something similar to a mantis shrimp 'punch' which generates cavitation bubbles well above the required auto-ignition temperatures. This is where using hydrogen gas becomes tricky as cavitation bubbles only form in liquid - the alternative is the dragon having an organic 'sparker' of some sort (probably on the outside of the body to keep it dry) like a flintlock musket.

[factotum]

Again from "Flight of Dragons", the dragons in that had a pair of growths in their throat they could knock together to create sparks, couldn't they? Something like that would be a deal more believable (and practical, for that matter) than somehow chemically generating 500+ degree temperatures.

[Brother Oni]

Again from "Flight of Dragons", the dragons in that had a pair of growths in their throat they could knock together to create sparks, couldn't they? Something like that would be a deal more believable (and practical, for that matter) than somehow chemically generating 500+ degree temperatures.

The book doesn't really go into the ignition system as far as I can remember. The cartoon has the 'Thor's thimble' in the roof of the dragon's mouth which generates significant amount of electricty (enough to shock Peter's tongue significantly for several seconds when he went probing to find it) as the ignition system.

The electric eel generates shocks of about 600V but the voltage required for an arc is complex, dependent on the humidity, gap to be jumped, altitude, etc. Looking up some values, you're looking at somewhere in the region of 10kV though, so it's unlikely that a dragon could use this mechanism.

Bear in mind, you only need a spark - you only need to light up one part and the fire will spread.

[Max™]

Just had to say this thread was an interesting experience to read.

Starting with horrific Dwarf Fortress flashbacks (CARNIVOROUS ELEPHANTS AGAIN? GREAT, HOW MANY EYES DO THEY HAVE AND DO THEY SPIT ACID OR WEBS?) before migrating onward to Pratchett and see-through dragons by way of a rather fascinating dissertation on Kaiju from Pacific Rim.

Now, as for how many dragons could a given area support?

I have one question: how much coal is available and accessible to said dragons?

Why coal? If ground up into a powder, perhaps strained through some sort of baleen equivalent, and better yet formed into tiny spherules through the use of a binding agent... mucus in this case I would think, you can take a hunk of a coal and turn it into a fine airborne powder which is just itching to explode.

Coffee creamer works well, but given the natural availability of coal and the history of coal dust explosions, it seems like a natural place to look.

Now, this would make perfect sense for a subterranean species which left the cave environment behind due to the... uh, explosive nature of their choice of chewing habits.

While gasoline or even hydrogen require an explanation for how the ignition temperatures are reached, coal dust is often accompanied by something which was known as a "damp", from "dampf", for "vapor", and is what led to the invention and widespread use of safety lamps. Some of the fun stuff you can find in a coal damp includes methane, hydrogen sulfide, and of course a carbon monoxide chaser to make sure the party really sucks.

Assuming you had a dragon with a coal "gizzard" that it used to sift and possibly grind coal into a powder, with a means to extract and contain the damps until needed, you could even plausibly argue that some of the various bacteria which metabolize coal are involved in turning raw stuff which might get scraped up and chewed on into something more like the primo anthracite type fuels.

If you put all of these together, a pouch which opens into the mouth that holds or sifts or even produces spherules of finely powdered coal dust, another pouch which passes along or even through the opening of the dust pouch and supplies methane/hydrogen sulfide/something along those lines, it might be hard to NOT ignite the stuff, pretty sure dust clouds can generate static charges on their own, I mean, there is a reason this stuff is so dangerous (I didn't learn until years later that the coal hoppers I once climbed around in for a job were MUCH more dangerous when empty than when full of coal, after all coal will only burn if you encourage it to do so, coal dust is going to do what it wants, and it probably won't be what you were hoping for) and has such a high rate of fatalities even today.

Possible coal dust production methods could include the reasonable but disgusting method of chewing up coal, getting a big glob of phlegm up, dribbling it out on a rock and letting it dry, then grinding the paste into a fine powder with some sort of baleen type screen/mesh growth(s).

Going from THAT to flight is a whole other ballgame which I am unsure how to approach... but honestly the idea of approaching anything to do with a creature which chews up coal, spits clouds of coal dust with the intent to ignite it like an overzealous special effects artist, AND has some means of flapping around above me?

Yeeeaaaaahhhhh, that's a big ball of nope.

[Mando Knight]

How about hydrogen instead of methane? It can be biosynthesized and it makes a pretty damn amazing fuel.

Methane can be bio-synthesized as well. A cow's rear end releases a lot of it.

[Brother Oni]

Possible coal dust production methods could include the reasonable but disgusting method of chewing up coal, getting a big glob of phlegm up, dribbling it out on a rock and letting it dry, then grinding the paste into a fine powder with some sort of baleen type screen/mesh growth(s).

Just one question - how do you keep the coal dust dry enough to ignite? The insides of a biological organism are rather wet and humid.



Going from THAT to flight is a whole other ballgame which I am unsure how to approach... but honestly the idea of approaching anything to do with a creature which chews up coal, spits clouds of coal dust with the intent to ignite it like an overzealous special effects artist, AND has some means of flapping around above me?

Hydrogen bioreactors also tend to have fairly toxic waste products depending on the synthesis route. A floating semi-transluecent photosynthetic beast which spews out flaming gas from one end and a combined jet of methane, hydrogen sulphide and water from the other end (among the typical urine and faeces) would also be a fairly big bag of nope for most people.


Methane can be bio-synthesized as well. A cow's rear end releases a lot of it.

There's also this ridiculously complicated pathway, which I think is tied up with methane metabolism, but I'm not sure.

http://www.chem.qmul.ac.uk/iubmb/enzyme/reaction/misc/miscgif/methane.gif

That said, most animal biosynthesis of methane tends to be from fermentation of plant material since digesting cellulose takes time and effort. While there have been many large reptiles that are herbivorous, all the reptilian predators have been carnivorous, if not obligate carnivores.

[Eldan]

There's also this ridiculously complicated pathway, which I think is tied up with methane metabolism, but I'm not sure.

Hehehe. Sorry, I just had flashbacks to introductury biochemistry lectures. That on that picture? Is considerably shorter and simpler than a lot of the pathways we saw there.

[Brother Oni]

Hehehe. Sorry, I just had flashbacks to introductury biochemistry lectures. That on that picture? Is considerably shorter and simpler than a lot of the pathways we saw there.

I guess things have advanced considerably from when I went to Uni. The most complex I had to learn was the Krebs cycle and where it ties into other pathways (I know I memorised it at one point, but I must have repressed it).

I was thinking about about the mechanisms involved with the methane carbon though (try following it around the cycle).

[Mr. Mask]

Max: Yeah.... those freaking elephants! (http://lparchive.org/Dwarf-Fortress-Boatmurdered/Update%201-2/)

Awesome idea with the coal. The toxins that a dragon might produce from this reminds me of legends of dragons spitting/breathing/biting poison. It makes me wonder if dragons might be able to process materials other than coal as well with that section of their body, and so might have a variety of breaths of fire or of poison. This would be interesting, as the resources of an area a dragon lives in could effect the nature of its breath (if intelligent, could they mix a cocktail of polystyrene, benzene, and gasoline...?).

As long as these dragons aren't just powder kegs they go off like Discworld (or, especially then), they will be all kinds of nope.

[Jeff the Green]

Actually, poison might be our savior here. "Breathing fire" was originally a metaphor for their poison. If we went that route, either making it venomous or figuring a way for it to produce an inhaled toxin that somehow won't affect them, we don't have to worry about the chemistry of fire breath.

[Mr. Mask]

Venom and poison is a good fall-back. Though, I think the fact it's difficult and needs discussion is the fun of fire-breath.

[Kato]

[...] all the reptilian predators have been carnivorous, if not obligate carnivores.
Isn't a predator carnivorous by definition? :smallconfused:

So, instead of discussing the impossible problem of getting a five ton reptile to fly we discuss the possibly solvable problem of getting it to spit fire? Sure, why not :smallbiggrin:

You know, since coal dust was suggested as a possible way to circumvent the more "expensive" gasoline, what about flour dust? Flour explosions can be pretty hazardous as well. Yes, I see the obvious problem: Dragons have never been associated with agriculture. But maybe it would be possible to grind some other kind of plant stuff into fine enough dust using a set of teeth, store it in some dry sack in the mouth and then exhale and ignite it. Would probably not make a flame thrower but it would be kind of spitting flame... maybe.

[Brother Oni]

Isn't a predator carnivorous by definition? :smallconfused:

Not always - they can be insectivorous (eg. small birds) or omnivorous (eg. humans) for example.

[Jeff the Green]

I think insectivory is a subset of carbivory. But the original point is off too. Gigantosaurusraptor (which I am standing under a model of—I love my job) was pretty massive and probably omnivorous.

[hamishspence]

On a planet of highly mobile plants - would a herbivore be a predator because it has to actually hunt its prey?

[factotum]

On a planet of highly mobile plants - would a herbivore be a predator because it has to actually hunt its prey?

There's nothing in the dictionary definition of the word "predator" which requires that its subject be an animal--it's simply any organism which survives by preying on other organisms. Under this definition, a pitcher plant is a predator!

[Kato]

There's nothing in the dictionary definition of the word "predator" which requires that its subject be an animal--it's simply any organism which survives by preying on other organisms. Under this definition, a pitcher plant is a predator!

So, what does prey/hunt involve? If we go by the "predators kill other organisms" herbivores are predators as well, but I guess "hunt" suggests the prey to be moving... Or at least hiding? Fighting back to some extent? This is getting out of hand :smalltongue:

(Also, regarding my earlier remark, I tend to casually consider omnivores just being which are carnivores and herbivores, which I know is technically wrong. But therefore my misconception/misstatement)


So, back to the dragon topic... opinions on my flour/dust suggestion?

[Eldan]

I'm not sure dust is any easier than a flammable liquid. In fact, it sounds more difficult to me. First, the dragon would have to find suitable material to grind down, then grind it down, find a way to keep it dry, then create a cloud from it. As opposed to liquid fuel, which it can sythesize itself, store more or less easily, then spit out. And both need an ignition source.

[Jeff the Green]

On a planet of highly mobile plants - would a herbivore be a predator because it has to actually hunt its prey?

Probably. Wikipedia (and, I presume, the textbook it gets the definition from) just says a predator is an organism that hunts other organisms for food. Shockingly, the question didn't come up in my ecology classes, so I can't verify it, though I'm familiar with creatures that hunt protists being called 'predators' (mostly informally, since most technical literature I've read prefers (primary/secondary/tertiary/etc. consumers' or more specific terms like 'cursorial hunter' or 'insectivore'), so it's clearly not restricted to things that eat animals. Etymologically there's nothing to restrict its usage either, coming from praedari, to loot, plunder, or pillage.

[Eric Tolle]

If we're dealing with real-world (or close to it) physics and biology, there's going to be some severe constraints on the size of our dragons, assuming they're going to be expected to fly. Q. northropi for example, had a wingspan of 11 meters, and a mass of 200 kilograms, as is pretty much at the high edge of feasible flight. Which can still be pretty impressive...


http://biyorss.com/wp-content/uploads/2010/10/giraffe.jpg


The alternative, of a hydrogen balloon dragon has so many biological imponderables that I think it can pretty much be safely dismissed as a possibility. But a venom-spitting, intelligent Q,. northropi with opposable thumbs could be far more than enough of a nightmare for anyone without a gun to deal with.

[Cikomyr]

If we're dealing with real-world (or close to it) physics and biology, there's going to be some severe constraints on the size of our dragons, assuming they're going to be expected to fly. Q. northropi for example, had a wingspan of 11 meters, and a mass of 200 kilograms, as is pretty much at the high edge of feasible flight. Which can still be pretty impressive...


http://biyorss.com/wp-content/uploads/2010/10/giraffe.jpg


The alternative, of a hydrogen balloon dragon has so many biological imponderables that I think it can pretty much be safely dismissed as a possibility. But a venom-spitting, intelligent Q,. northropi with opposable thumbs could be far more than enough of a nightmare for anyone without a gun to deal with.

We need some scales on that, for defensive purposes, no?

[Stardrake]

On fire, let's do some basic calculations.

On Wikipedia, I found data on some WWII flamethrowers.

An M2, the American flamethrower of choice, uses half a gallon of gasoline per second and, for a flamethrower, has a relatively short range of 20-40m. Seems fitting.

Gasoline contains 120 MJ/US gal.

So, if a dragon is comparable to a WWII flamethrower, a two second blast of fire uses 120MJ. Which is about 29 million calories, i.e. 29000 kilo calories.

Top beef is about 300 calories per 100 g, so our theoretical dragon would need... about ten kilos of meat for two seconds of fire.That's pretty close to my thinking of how dragons might breathe fire (coupled with a bit of white phosphorous or bioelectricity to ignite it). However, if we're looking at a hydrocarbon mix, the dragon might not be fuelling the fire by eating meat, but may be able to drink hydrocarbons directly. In which case it won't factor into how much meat they need to eat to produce a flame, but something you would need to enter into the calculations is the availability of hydrocarbons so the dragons have something to flame with. That said, I never worked out what the chemistry would be needed for the dragon to synthesise WP out of something it could feasibly find in nature.

Mind you, one possibility here is that dragons may be somewhat omnivorous - they eat meat for their own sustenance, but convert plant matter into hydrocarbons.


A hydrogen bioreactor would be much more effective, but given that such naturally occuring systems require sunlight, we're looking at a semi-translucent photosynthetic dragon.
Seen that done, actually, without the hydrogen bioreactor part. The general idea was that the photosynthesising compounds are mostly in the wings (from memory, in fact, the dragons in the series in question actually couldn't fly - solar collector was the primary purpose of the 'wings'.)

An acidic spray that burns victims is also another way of getting around it that I've seen (see the Liveship Traders and following series). That said, this might be a simple way of turning one of the downsides of the volatile chemistry of firebreath into an upside - the various poisonous waste products also get stored to be used as a weapon when, for whatever reason, the dragon doesn't want to breathe fire.

Kinda explains the oldschool gold dragons that had the fire breath of reds and the chlorine gas clouds of greens...

[Metahuman1]

The book doesn't really go into the ignition system as far as I can remember. The cartoon has the 'Thor's thimble' in the roof of the dragon's mouth which generates significant amount of electricty (enough to shock Peter's tongue significantly for several seconds when he went probing to find it) as the ignition system.

The electric eel generates shocks of about 600V but the voltage required for an arc is complex, dependent on the humidity, gap to be jumped, altitude, etc. Looking up some values, you're looking at somewhere in the region of 10kV though, so it's unlikely that a dragon could use this mechanism.

Bear in mind, you only need a spark - you only need to light up one part and the fire will spread.

Yes they did have the thing in there mouths/throats that caused electrical current to light the gas. And while they showed the spark in the movie, I'd forgive that as "We needed to show not tell cause visual medium.", and say if it was for real the amount of electricity needed would be significantly less.

Edit: And about that thing were they'd need to be Translucent to produce the gas to burn. Could maybe just part of them be translucent and they need to sun that part semi-regularly? Say, just the wings? And it has valves and such to transfer the produced gas into the Torso to provide lift to help fly and fuel for fire breath?

[Brother Oni]

Yes they did have the thing in there mouths/throats that caused electrical current to light the gas. And while they showed the spark in the movie, I'd forgive that as "We needed to show not tell cause visual medium.", and say if it was for real the amount of electricity needed would be significantly less.

Looking up some alternate sparking ignition systems, with the right equipment, you only need a 1.5v battery to generate the 1.1kV that will cause a spark that will jump 1mm. I've no idea how a biological system would simulate a piezo-electric crystal and a circuit/transformer to convert DC to AC though.



Edit: And about that thing were they'd need to be Translucent to produce the gas to burn. Could maybe just part of them be translucent and they need to sun that part semi-regularly? Say, just the wings? And it has valves and such to transfer the produced gas into the Torso to provide lift to help fly and fuel for fire breath?

Possibly, although the wings would be fairly 'sloshy' with all the liquid required to run the bioreactors. I'd also wouldn't think air valves, more like dissolution of the hydrogen then pumped via the circulatory system into the float bladder, where the hydrogen can diffuse/degas out of solution, either via a selectively permeable membrane or some sort of ion channel.

[Zombimode]

I think we have to differentiate between two questions here:

a) How many dragon-shaped animals could live on earth?

and

b) How many actual dragons (from setting XY) could live on earth?


Those are two very different questions. To elaborate: a dragon-shaped animal is a creature resembling in its appearance the beasts of fantasy and mythology. But its abilities and shape are bound by what is scientifically possible. It is probably not sapient.
If it can fly, it needs a body actually capable of flight on its own accord. That rules out most contemporary renditions of dragons. Or at least those, that I personally enjoy the most: todays dragons are quite bulky, massive and strong creatures, enhancing the imagery of power and dominance.
If it has any sort of breath weapon, it is most likely quite different from the typical fire cones, lightnings or negative energy clouds.
Of course, no kind of supernatural ability like spellcasting is not possible as well as any association to the metaphysical.

Answering this question is probably a difficult but interesting endeavor, and most responses in this thread so far go in this direction.


Question b) is easier to answer, at least on the surface. We just need to research the abilities and nature of a specific type of dragon, implant creatures of that type on earth and extrapolate from there.
Dragons from RPG settings are especially suitable for this since they are probably quite well-defined (http://www.d20srd.org/srd/monsters/dragonTrue.htm).
Of course it can get tricky. How would supernatural creatures of huge size and power and quite the intelligence affect the current human societies? Not an easy question.
Also, if dragons are of a special importance in a given setting, does this importance "carry over"? I.e. if we look at the question "how many Eberron dragons could live on earth", it is then also true that the world composed of the three ur-dragons Siberys, Eberron and Khyber from which the dragons are descendants?

Many issues problematic in question a) aren't as important here because they can be answered in the same way as they are in the original work.
For the problem of food consumption, the AD&D monster manual states that dragons can eat pretty much everything and can live from almost no food at all. Bronze Dragons are stated to lift the dew in the morning with their tongues.

[Mr. Mask]

No one seems to know a method to guess at how large a species might be. So, that information would be useful to work out how many calories and what prey species, but it wouldn't get us any closer to answering the question.

[Jeff the Green]

The problem with guzzling hydrocarbons is that they tend not to be located above ground. I suppose we could give them mile-long, carbide-tipped probosces, but I'd think the mythology would have mentioned that.

I suppose you could have them prey on whales and process the blubber into oil.


No one seems to know a method to guess at how large a species might be. So, that information would be useful to work out how many calories and what prey species, but it wouldn't get us any closer to answering the question.

Sorry, I'm not sure I understand. Why would we need to estimate the size? Isn't it kind of stipulated by whatever fiction we're drawing from?

[warty goblin]

As anybody who has read the excellent proofs of all things dragonic presented in Stanislaw Lem's seminal text on over-applied mathematics and integral poetry, The Cyberiad could tell you, the real issue with dragons is one of probability. A dragon is simply very improbable. However once an individual has caused sufficient distortion to the probability of a dragon, they become too probable, and the problem shifts from one of altering probability distributions to one of pest control. Probabilistic pest control, since any given dragon may or may not exist at any particular moment. The correct answer to this question is clearly that the Earth will support an arbitrary number of dragons, but at any given instant, each dragon has non-zero probability of not existing. The dragons, naturally, have a say about existing or not as well, which makes hunting them particularly challenging.

If ya'll knew the classics, I wouldn't have to explain simple little things like this.

[Excession]

I suppose you could have them prey on whales and process the blubber into oil.
I like that idea. I wonder if pine tar would be another option. Dragons "farming" pine forests by scoring the trees and returning for the sap seems a bit off though.

[Mr. Mask]

Sorry, I'm not sure I understand. Why would we need to estimate the size? Isn't it kind of stipulated by whatever fiction we're drawing from? I'm afraid I really don't understand. The thread title is, "How Many Dragons Could Live on Earth?" so I didn't expect it to be difficult to understand that such a question was a matter of interest. Most fiction tends to say there aren't many dragons, but it doesn't often go into the subject in reasonable detail.

[Stardrake]

It is probably not sapient.
There's an interesting question, actually. Despite the term 'bird-brain', birds are actually probably one of the smarter groups alongside primates, cetaceans, and (arguably) cephalopods. There seems to be something about the combination of warm-bloodedness (except the last) and living in a three-dimensional environment (arboreal counts).

So if we imagined a warm-blooded dragon large enough to carry a human-sized brain - I could well see that developing intelligence that's at least close to sapience. The main issue is that most dragons, as with most large predators in nature, are solo predators - one of the other drivers of complex language and sapience is social behaviour.

Plus, if they're sapient, they'll probably need to eat more. Sapient brains are energy-hungry organs.

[Jeff the Green]

I'm afraid I really don't understand. The thread title is, "How Many Dragons Could Live on Earth?" so I didn't expect it to be difficult to understand that such a question was a matter of interest. Most fiction tends to say there aren't many dragons, but it doesn't often go into the subject in reasonable detail.

Okay, I think I understand. Generally 'species size' means length, weight, etc. what you're looking for is 'population size.

And as I said above, I would be very surprised if such a method exists. There are too many variables and they interact differently. Plus some variables are determined by the life history of the creature itself, which are kind of arbitrary for a fictional creature.

[Mr. Mask]

That explains the confusion. Sorry, I did mean population size.

Well, I guess I'll take from this that there could potentially be a lot of dragons, or you could reason small populations. It does go against something someone told me, that species would expand to their full potential size rapidly regardless of what they are.

[Jeff the Green]

It does go against something someone told me, that species would expand to their full potential size rapidly regardless of what they are.

Well, yes and no. On the one hand, they will increase on a sogmoidal curve to (roughly) their maximum population size. On the other hand, the maximum potential population size is highly variable across space (as I said) and time.

Also, how rapidly they increase depends on whether they're r or K specialists (http://en.wikipedia.org/wiki/R/K_selection_theory) as well as whether there's something like predation tamping down their r. For example, if all poaching of elephants stopped right now (which would bring their r up to the positives), it would take centuries for them to reach their former numbers because even with optimum conditions elephants' r is so small because of long gestation periods, long interpregnancy intervals, and the great length of time before a newborn elephant could become sexually mature.

[Mr. Mask]

That was my response, too. That elephants and rats have very different breeding rates. The subject was whether elves in a world similar to the modern one would have small populations compared to the resources at their disposal, and more specifically compared to human populations with similar levels of resources.

[Jeff the Green]

Well, when you get to beings of humanoid intelligence things change. Birth control can reduce r to 1 (i.e. no growth) and, if people decide to use birth control more as the population grows to avoid a Malthusian crisis, reduce K. So if elves use birth control to keep their population to where it doesn't harm their forests, they could definitely have a lower maximum population size. On the other hand, if they don't and the only difference is that elves' r is lower due to generation length, eventually they'd both hit the same maximum (though they'd recover much more slowly from plagues, wars, and the like).

[Mr. Mask]

I realize that eventually they'll come to fill their population potential, unless measures are preventing them. I'm not studied on the details of population/resource growth with technological and social advancement, so I wasn't sure if it was possible that a gap could rise between elves and humans due to continual increase of resources. Say, if there was continual expansion of resources and the elves' population wasn't keeping up with it, overtime you'd have a significant gap grown between them and the creatures which did keep their populations close to (or exceeding) their resources (actually, the point of exceeding resources, humans having a lower standard of living than elves, could help make for the situation where elves are outnumbered). Of course, I'm not sure that resources do grow at substantial enough rate to allow such a line of events.

[Jeff the Green]

Well, I know enough about population growth and the green revolution to give a rough estimate. It involves math and it's 2:00 am here on the West Coast, so I'll work on it tomorrow, maybe Monday.

[Mr. Mask]

I'd be very interested to read your analysis on the subject, if it's not too much trouble.

[Jeff the Green]

Alright, I've finally had some time to play with it. I used the r/K population growth model (http://en.m.wikipedia.org/wiki/R/K_selection_theory). I also assumed a human population growth sixteen times that of elves; this is probably far too small of a difference, but if I made the discrepancy any greater it wouldn't have fit on the graph. Anyway, the graphs are here (https://docs.google.com/spreadsheets/d/1gZzZ0HRQGGXWDIWEuaYusKwPpb2D5R-pAB8wdCjxFkk/pubhtml#). (I can't make the graphs bigger, but you can by just increasing the zoom in your browser.) Both versions have starting populations of 1000 for both species and an initial carrying capacity of 10,000. They both also have two periods of "green revolution" where the carrying capacity increases to 11,000 and then 12,000 with 1500 years between them. In the "saltation" version the green revolutions take place over a period of time less than 100 years; in the "steady growth" versions each takes place over 1000 years.

Two interesting things stand out. Over the period I simulated, it takes an enormous amount of time for elves to catch up with the humans. If the creation of the races or some catastrophe occurred relatively recently, it's likely that the elves have a lower population size than humans by virtue of generation time alone, and this is only made worse if you assume a 100-fold or greater difference in their population growth rates rather than a 16-fold one.

Second, I'd rather be an elf than a human. Because of their more rapid growth, humans suffer cycles of boom and bust during the green revolution: essentially, they begin reproducing at a higher rate as soon as food supply increases, but outstrip gains and the population crashes, then it rises too fast again, then crashes, for some time. It's also surprisingly worse with steady gains. Because elves' population growth is so much slower, they never outstrip the food supply.

[Stardrake]

On the second point:

For any given individual of the species, I think it's pretty much always better to be a member of a K-selected species than an r-selected one: partly because individuals in K-selected species are valued more highly, receive more investment from their parents, and are generally better off, and because of what you point out regarding how the two distinctions behave when resources available are increased. r-selected species may be more likely to survive shocks as a group, but that doesn't help the individual much.

[Jeff the Green]

For any given individual of the species, I think it's pretty much always better to be a member of a K-selected species than an r-selected one: partly because individuals in K-selected species are valued more highly, receive more investment from their parents, and are generally better off, and because of what you point out regarding how the two distinctions behave when resources available are increased.

Not necessarily true. In humans, for instance, there are very strong allee effects (http://en.wikipedia.org/wiki/Allee_effect). Part of the reason our standard of living now is better than it was 5000 years ago and why it's grown so much faster is that we have much larger population sizes and so can take advantage of economies of scale and we have more scientists working on ways to make our lives easier.

Also, elephants and baleen whales are more K-selected than humans. I'd rather not be either right now.


r-selected species may be more likely to survive shocks as a group, but that doesn't help the individual much.

Also not necessarily true. r-selected species can bounce back faster, but because they put less investment into each individual they are each much more likely to die off and a massive catastrophe is particularly dangerous. For instance, if a massive fire swept the entire Oregon High Desert (http://en.wikipedia.org/wiki/High_Desert_(Oregon)) there would be plenty of ponderosa pines standing because they tend to survive the kind of fires that are common there (low intensity, low flame height) but sagebrush would be extinct. I can also imagine events that could kill off r-selected species preferentially: radioactivity, for one, since r-selected species' germ lines undergo mitosis much more often and it's during mitosis that DNA is most vulnerable. (Members of K-selected species would certainly die off from cancer, but that's not something that's strongly selected against.)

[Mr. Mask]

Thanks for the research, eff. I've found it very educational. The gap surprised me somewhat.

Something I was wondering, though. Did you presume most of the elves to remain alive due to immortality/long life and resistance to sickness? I wondered how a lack of population death might effect things (it appears in scifi, sometimes).

[Jeff the Green]

Something I was wondering, though. Did you presume most of the elves to remain alive due to immortality/long life and resistance to sickness? I wondered how a lack of population death might effect things (it appears in scifi, sometimes).

The model isn't that detailed, but that's incorporated into r. Basically it's calculated as (births - deaths)/total population. I'm not entirely sure how the longer lifespan would affect r, but I suspect that once you've got a population with the full spectrum of ages it won't particularly matter. Sure they're living longer, but they're still dying eventually. The only way it'd matter is if elves kept reproducing their entire lives, which isn't the case in most fiction I've seen, including D&D.

Edit:

Er, rather r = 1 + (births + immigration - deaths - emigration)/total population. An r of 1 is stasis, an r of 2 is a doubling, and an r of 0 is extinction.

[Metahuman1]

So, here's a slightly different track of thought. If we assume the dragons have fire breathing and flight and are generally pretty big and strong physically, and we assume them to be of comparable intellect to humans, what does this do to the equation?

[Jeff the Green]

So, here's a slightly different track of thought. If we assume the dragons have fire breathing and flight and are generally pretty big and strong physically, and we assume them to be of comparable intellect to humans, what does this do to the equation?

Absolutely massive energy requirements. It's not my area of expertise, but I think that warm-blooded ness is required for a big brain. And the human brain requires an enormous amount of calories. Though it's been challenged, the current thinking is that the for a given intelligence you need a similar ratio of log(brain mass):log(body mass). (It's more complicated than that, but it's good enough for here.) so such dragons would have massive brains. I'm not sure you could plausibly feed such a creature.

[Stardrake]

Not necessarily true. In humans, for instance, there are very strong allee effects (http://en.wikipedia.org/wiki/Allee_effect). Part of the reason our standard of living now is better than it was 5000 years ago and why it's grown so much faster is that we have much larger population sizes and so can take advantage of economies of scale and we have more scientists working on ways to make our lives easier.

Also, elephants and baleen whales are more K-selected than humans. I'd rather not be either right now.I see where you're coming from, but my statement had a certain assumption of 'all else being equal' to it. Allee effects can only really kick in if they have mechanisms to do so, and in humans, many of the things that give our species such strong Allee effects (language, inventiveness, and so on) are adaptations that push us more towards the K-selected end of the scale. Adaptations that pushed us closer to the K-selected end of the scale might actually make humans better off than anything from the Allee effects - increased intelligence per individual, coupled with increased average lifespan allowing an exceptional individual to remain inventive for longer (imagine if the likes of Newton, Einstein, and so on had an elf's lifespan...) could lead to a similar rate of advance than a larger number of shorter-lived, less intelligent scientists and engineers, for example. Stronger immune systems and less compromises in long-term health for the sake of higher reproductive rates could mean that we need less medical research to achieve the same (or better) overall quality of life. And so on.

Elephants and baleen whales I'd see as comparing the proverbial different forms of fruit. While they may technically be more K-selected, what it really boils down to is that they're less optimised - the human combination of the intelligence to come up with complex tools, the right limb structures to construct them, and a complex enough form of communication to pass on these skills is a winning one that probably means that humans are actually doing better on the K side of things than either, even if they also manage to have a significantly higher r as well. To really compare, we'd need to compare to another species that has those three traits but which has a different focus on the r/K distribution. Some of our closest relatives might count, but really we'd be looking at fictional sapients like elves and goblins for this.

And certainly, between an elf (extreme K-selected among fantasy sapient humanoids) and, say, goblins or kobolds (extreme r-selected), I know which generally has a better life. The exception is when the r-selected competitor uses their faster reproduction rate to drown the K-selected species in numbers.

[Arcane_Secrets]

They probably could synthesize something very close to gasoline. Various medium-sized hydrocarbons, at least. But yeah, my calculation was a best-case scenario, and not a likely one.

How about hydrogen instead of methane? It can be biosynthesized and it makes a pretty damn amazing fuel.

What about some kind of exotic organic peroxide, or a low MW ether?

[Brother Oni]

What about some kind of exotic organic peroxide, or a low MW ether?

While hydrogen peroxide is used at a cellular level (it's a component of lysosomes), synthesising a large amount of it may be problematic since it wants to react with everything, including the inside of the dragon. I don't think it's possible to do the same trick with H2O2 as with HCl (coat the inside of the containing organ with a constantly generated thick mucus).

Some checking indicates that biosynthesis of ethers are heavily tied into lipids, so may not be possible to generate separately.

Edit: I failed to read the question properly and have actually looked up an organic peroxide, specifically acetone peroxide, and dear sweet merciful non-specific deity, you're proposing to synthesise that inside an organic being? Are you familiar with the swamp dragons from the Discworld series? Because I'm fairly sure what's what you're going to end up with (mostly scattered about the landscape).

[Arcane_Secrets]

While hydrogen peroxide is used at a cellular level (it's a component of lysosomes), synthesising a large amount of it may be problematic since it wants to react with everything, including the inside of the dragon. I don't think it's possible to do the same trick with H2O2 as with HCl (coat the inside of the containing organ with a constantly generated thick mucus).

Some checking indicates that biosynthesis of ethers are heavily tied into lipids, so may not be possible to generate separately.

Edit: I failed to read the question properly and have actually looked up an organic peroxide, specifically acetone peroxide, and dear sweet merciful non-specific deity, you're proposing to synthesise that inside an organic being? Are you familiar with the swamp dragons from the Discworld series? Because I'm fairly sure what's what you're going to end up with (mostly scattered about the landscape).

No, I'm not familiar with swamp dragons. However, acetone peroxide was closer to what I had in mind (I was also thinking of ether peroxide as a possibility (MeCH(OOH)OEt)). What if you used a system similar to what bombardier beetles used, in which the components are stored separately, but are then mixed and then a brief amount of a catalyst added to start the explosive reaction?

Thinking about your response as well, just how organic do dragons have to be with regards to the particular anatomical elements involved in this? What if the portions of their upper respiratory tract and mouth in which this takes place are armed with deposited minerals so that way they don't react with the kinds of reactive chemicals necessary?

[Brother Oni]

The only real thing you need to know about Discworld swamp dragons is that they tend to explode when excited or unwell (which is all the time). A more detailed description can be found at the Discworld wiki (http://wiki.lspace.org/mediawiki/index.php/Swamp_dragon).

I'm going to need to look up some synthesis routes to check the possibility (and hopefully not end up on a different government watchlist while I'm at it). Having a binary chemical synthesis system where the components are inert sounds quite reasonable, but they need to react and be expelled very quickly (but smoothly), mainly because the resultant peroxide is very shock sensitive, especially when wet. The inert components method would also probably negate the need for an non-reactive storage system.

I'm not very familiar with the burn characteristics of acetone peroxide but wouldn't a sprayed explosive liquid work more like an airburst explosive rather than flamethrower? More bang than flame?

[Metahuman1]

Absolutely massive energy requirements. It's not my area of expertise, but I think that warm-blooded ness is required for a big brain. And the human brain requires an enormous amount of calories. Though it's been challenged, the current thinking is that the for a given intelligence you need a similar ratio of log(brain mass):log(body mass). (It's more complicated than that, but it's good enough for here.) so such dragons would have massive brains. I'm not sure you could plausibly feed such a creature.

So, sentient dragons would have to be small, not breath fire, and/or not fly, to work?

That's a bummer.

[Stardrake]

To be honest, I'm not sure I buy that requirement. More body mass needs more brain mass devoted to keeping that body running, sure, but the extra amount needed to go from Intelligence 0 to Intelligence 3d6 shouldn't in itself need to scale up much because body mass has scaled up.

It's certainly true that some birds can be quite smart despite smaller brains, but that can probably be chalked up to needing their brains to be more efficient rather than being simply because they have less body mass. And any flying creature is probably going to have a similar efficiency requirement.

[Metahuman1]

Oh, cool, then big, flying, fire breathing (though probably with a shot limit, particularly if they want to keep using the flying part as already touched on.) physically fairly strong dragons that are sentient is still a thing that we can speculate on.

So, that in mind, back to my first question. How does them being Sentient change the game here?

[Stardrake]

Sapient. 'Sentient' basically just means 'can perceive itself as different to the environment around it, and can consciously react to the environment'. Sapiency is 'has humanlike intelligence, typically defined as possessing a language capable of expressing abstract concepts'. They get mixed up a lot, but in the animal kingdom, sentience isn't actually a lot to be excited about, while sapiency is something where the list of candidates outside humans is a short one.

Anyway, nitpick aside...

I think I read somewhere that the human brain actually consumes roughly a quarter to half of total calories consumed. So if it did scale up, then you'd be taking a creature that already requires a lot of food (warm-blooded, flying) and bumping up what it needs by twenty five to fifty percent. Welll... it would explain why dragons tend to hibernate a lot and to be highly ravenous when active.

[Eric Tolle]

So, sentient dragons would have to be small, not breath fire, and/or not fly, to work?

As I mentioned upthread, a flying dragon is gong to be limited in mass anyway. A 200 kilogram Quetzalcoatusderived dragon could have a bran n the siaze range of a human. And fire has a lot of problems with being created- something like venom would bbemore appropriate.

[Jeff the Green]

To be honest, I'm not sure I buy that requirement. More body mass needs more brain mass devoted to keeping that body running, sure, but the extra amount needed to go from Intelligence 0 to Intelligence 3d6 shouldn't in itself need to scale up much because body mass has scaled up.

It's certainly true that some birds can be quite smart despite smaller brains, but that can probably be chalked up to needing their brains to be more efficient rather than being simply because they have less body mass. And any flying creature is probably going to have a similar efficiency requirement.

See this post:


Absolutely massive energy requirements. It's not my area of expertise, but I think that warm-blooded ness is required for a big brain. And the human brain requires an enormous amount of calories. Though it's been challenged, the current thinking is that the for a given intelligence you need a similar ratio of log(brain mass):log(body mass). (It's more complicated than that, but it's good enough for here.) so such dragons would have massive brains. I'm not sure you could plausibly feed such a creature.

Plus, the efficiency of the brain is probably a larger selective pressure on primates than anything but the smallest birds (which are not exactly renowned for their intelligence). Our brains use something like 20% of our energy budget, far more than ravens or parrots.

[Mr. Mask]

Birds have been getting more respect for their intelligence, of late. Crows manage some pretty amazing puzzles unaided, Einstein the grey parrot was a very interesting case (though rare among his kind), and the ability some possess to express language to an extent rivalling apes.

[Max™]

Seeing (and hearing, good lord Cumberbatch is great for it) Smaug recently makes me want to see the Silmarillon done just for this big bastard stomping around:
http://img1.wikia.nocookie.net/__cb20120521124402/lotr/images/4/42/Dragon_of_the_First_Age_by_rubendevela.jpg

[Brother Oni]

Seeing (and hearing, good lord Cumberbatch is great for it) Smaug...

You should see the behind the scenes motion capture of him playing Smaug: link (http://www.youtube.com/watch?v=1SfQpGORLr8).