Why would humans be the dominant species?

Question

Humans, in most fantasy stories including in my own, are the dominant species. Why is that? Firstly, I guess I should give every race in my story strengths and weaknesses.

Humans

(same as us) have the best endurance

Orcs

Strengths: twice as strong and have a mildly improved sense of smell

Weaknesses: are slightly slower and have the worse endurance

Elves

Strengths: have better eyesight and hearing, are faster and more agile, have a slightly stronger grip, and live twice as long

Weaknesses: are the weakest, are more susceptible to injuries, and are the least fertile

Halflings

Strengths: finer motor controls, best eyesight, and are proportionately stronger than humans

Weaknesses: shortest

Goblins

Strengths: have the best sense of hearing and smell, and are proportionately stronger than humans

Weaknesses: shortest, and have slightly worse eyesight

Dwarves

Strengths: proportionately the strongest, and have slightly better eyesight.

Weaknesses: somewhat shorter, and are the slowest

Now given all of this in a world with multiple hominids (all of which are just as smart as us) why would humans be the dominant race, and why wouldn't they just kill all the other races?

NOTE: Magic does not exist in my story

Answer 1

In a world with multiple sapient humanoid species, humans probably wouldn't be outright dominant.

In nature when you have multiple similar species coexisting together, they usually do so because they occupy slightly different niches from one another. This actually happened with humans, about 3 million years ago you had Ardipithecus adapted for living in trees, Australopithecus adapted for a more ground-dwelling omnivorous lifestyle, and Paranthropus specialized in feeding on roots and tubers. These species coexisted because they all had distinct ecological niches they outperformed the other species in.

In a fantasy world with orcs, elves, dwarfs, halflings, and goblins in addition to humans, you would have some environments where humans would do better in and others that other species would do better in. You already see this a bit in fantasy where dwarfs have their cities in the mountains and elves are able to exploit the forest much better than humanity. The thing is that most settings don't give examples of where humans outperform everyone else. Humans just end up dominant mostly because a human is writing the book/directing the movie/etc.

Humans would outperform all of the other species listed in open grassland and savannah habitats. High endurance would serve us best there, and none of the other species listed seem to be as well-adapted for running on open ground as humans. Orcs are heavier and more robust, halflings, goblins, and dwarfs have short legs, and while elves may be more agile that may not be as useful on open plains if they are not as strong and more susceptible to injury (think predators in an open field).

Indeed, given the presence of other species humans are liable to become more selected for grassland habitats, with longer legs, greater endurance, etc. This is called character displacement, where in the absence of competition a species becomes more generalized but in the presence of similar competitors the most extreme variants of their anatomy become selected for. Humans coexisting with other humanoid species, even if they were numerically or ecologically dominant, may not closely resemble what we would consider the norm for Homo sapiens at all.

In this scenario many human cultures might resemble pastoral or nomadic human cultures in our world. Humans would probably make the most use of horses, and most of your steppe warlords waging military conquest on horseback would be humans because humans have access to the best horses. You also might get a lot of humans becoming traders and running trade caravans between the other species, because not only do they have all the best draft animals but they are also good at making long treks over open terrain like you get in deserts or plains. This might be one reason you see humans everywhere: humans aren't dominant but because of their migratory habits and tendency to be merchants they still get everywhere.

The whole "humans breed faster" has been brought up here and has been used in other fantasy settings (The Witcher, Dungeons and Dragons, and Warhammer 40,000 come to mind). The thing is, if you take one look at human biology the idea of us being able to outbreed anything is utterly silly. Homo sapiens is one of the most K-selected species on the entire planet, except for elephants, whales, and a few others, and there's evidence we are K-selected even compared to other hominins (Neanderthals might have had shorter juvenile periods, Homo erectus doesn't seem to have had the tortuous pregnancy that we do). We require some of the most parental care of any species, have the longest juvenile phase of any mammal, have incredibly high rates of death by childbirth without external aid, etc. The way our species works is that we put a ton of effort into protecting what babies they do have such that juvenile mortality is very low. You might be able to have a species that is even more K-selected (read: elves) since whales and elephants manage to do it, but its unlikely humans would be notable for having lots of offspring because we are some of the slowest reproducing animals that have ever existed.

Another common answer in these scenarios is "humans are such bastards we killed everyone else until we became dominant". The thing is if humans are aggressive you have to answer the question of why other humanoid species aren't the same way. One reason why it's thought that humans are so aggressive in dealing with predators is we are slow and lack natural claws, teeth, or weaponry, and if we are caught off guard without knives, spears, or bows-and-arrows we are essentially helpless, even against an armed human. Mobbing predators and getting rid of them through proactive violence is about all we have. Dwarfs, elves, halflings, goblins, and orcs all have the same handicaps as humans:

• They are erect bipeds so they are going to be slow relative to most quadrupedal animals because the muscles most animals use for fast locomotion have been reorganized into supporting the spine in erect bipeds.
• They are more or less human-like in shape, they have no fangs, claws, horns, natural armor, or anything to fight back. The only exception is if your orcs and goblins have tusks.
• They have no options for escaping predators if one comes upon them unarmed. Elves might be able to climb trees depending on your design. The rest of them are going to be just as helpless as humans, if not moreso because of their smaller size.

Given this, it raises the question of why wouldn't these other species be as aggressive as humans in dealing with threats due to their similar weaknesses.

Humans are likely to have a tendency towards total war that the others don't if their endurance is higher. Most species tend towards skirmishes because they tire out easily and fighting isn't worth it.

People here have mentioned that humans are "adaptable". The thing is that in ecology in most circumstances "adaptable" doesn't mean "numerically dominant". Usually in nature highly adaptable species don't do very well compared to specialists and under normal circumstances end up marginalized. It's the "jack-of-all-trades, master of none" thing. If you're an opportunistic omnivore, that means that herbivores digest plants better than you (and can often digest poisonous plants that for you would be a waste of time), carnivores catch prey better than you (and with their specialized implements can kill prey more dangerous than you can handle), insectivores can digest insects better than you, etc. The only time adaptable species do better is in disaster scenarios, where being able to eat anything is an advantage. Specialists thrive under normal conditions, but they don't survive when disaster comes, which means the generalists have the long-term advantage. But in these scenarios you do not have the generalists being numerically dominant unless most of the competition is dead.

Alternatively, humans are a hybrid species between all of the above

If all of the aforementioned species can breed, it may be that humans are the hybrid result of gene flow between these populations after prior isolation. This is sort of where modern humans came from, and if Neanderthals and Denisovans had larger population sizes it is likely that modern humans would show more signs of being a mix. In this scenario, the human form would probably first arise among trader families carrying goods between populations (the lifestyle might also favor adaptations for travel and might explain human high endurance) and then spread out from there due to continued intermarriage, population mixing, and the fact that these hybrids lack many of the pronounced weaknesses of their parent species.

Realistically humans might be better described based on their degree of ancestry from each species and often don't look that similar to one another, but in practice humans are so mixed it is an exercize in futility. Immigration from strongholds of other species into human territory ends up getting absorbed into the human gene pool and not having noticeable effects because humans are just so diverse to begin with. You would end up with a situation like the red wolf: coyotes do really well on open prairie, wolves do better in dense forest with lots of prey, but everywhere else the hybrid form (red wolf) outperforms them ends up being dominant.

Answer 2

We outnumber others, either by out-breeding them at some point in time or by out-killing them. Use one or combine at your leisure.

The source can be technological or biological.

Technological edge:

Hard edge, by outkilling the others:

Humans were the first who discovered how to smelt iron. While the others were still using bronze armor and swords, here came humans with iron swords and shields and armor. It was absolute slaughter. Humans got advantage by either killing or enslaving other races.

Humans were the first race who discovered guns.

Humans are absolute psychopaths when it comes to battle for survival: other races give up after some damage, we fight to the bitter end. And not only that: kill one of us in our village, we band together and kill your whole village.

Ye may kill for yourselves, and your mates, and your cubs as they need, and ye can; But kill not for pleasure of killing, and seven times never kill Man!

Rudyard Kipling, The Jungle Book

Humans are extremely territorial as well. We don't run from dangerous animals, we band together, get our spears then go out and kill them. And keep killing them, to keep our territory free from other predators and what we perceive as harm.

Basically, for every single dangerous animal you can think off, there was at least one person somewhere thinking long and hard "I wonder how I can kill it. A spear? An arrow through the eye? A knife? A trap? Everything to remove that gator/lion/dragon from the water source."

or "It is venomous, I wonder what can I do if it bites me? Cut off my hand? Make antivenom? Say my prayers and tell others that it is venomous and don't touch it and to kill it on sight with a large spear/ huge stick?" etc.

Soft edge, outbreeding and outsurviving :

Humans were first who started industrial revolution / found out how to have their children reliably survive to adulthood. We found out how to purify water (by boiling it in order to make beer and giving resultant beer to children, instead of dirty water), we found out how to have our women and children survive childbirth, we found out how to keep our kids alive (Hint: children are more fragile and susceptible to cold than adults, thanks to losing heat faster because of their smaller stature. Who knew?! We did!) until they reach adulthood. We found vaccination against common diseases. The vaccines don't work for other races. We found out how actual medicine works for our species. The others go to witch doctors. We invented dentists. The others go to blacksmiths to pull their infected teeth out with tweezers.

Humans were the first to find out how to agriculture. Optional: The plants we decided to cultivate are mildly to horribly poisonous to other races but are fine to us. Or just taste bad for them. You don't want those dirty goblins and elves stealing from you, right?! So don't grow things they can eat on your field!

Which leads to displacement: If you burn a forest that has food which elves and dwarfs can eat and replace it with fields with food they can't eat, what are they going to do?

That's basic habitat destruction, that is.

Biological edge:

Due to glitch in biology, other races find us extremely sexy /authoritative/scary on instinctual level. It's a supernormal stimulus.. Our females are like super models for other races. Our males look scary like bears or sound like gods to them. Or something like that.

They find our children absolutely adorable and cute. In fact, our babies are like cuckoos for them: so adorable they forget to take care of their own children all so they can care for ours. Again, see supernormal stimulus. Our babies crying sounds a lot like their babies crying (similar like cat meowing sometimes sounds like baby crying), but the opposite is not true.

Or maybe they find our adults absolutely adorable and cute? For example, because goblin child has smooth face and large eyes and sometimes furry cheeks which adult goblins lack. But human adults have in abundance!

Other races can breed with human females but the resulting offspring is always fertile genetically human female. Other races can't interbreed with anyone but humans.

Human males breeding with females of other races leads to for (original race) sterile half-orcs, half-elves etc. Unless the resultant half-human offspring breeds with human females, which has 50% chance of getting fully human offspring and 50% chance of miscarriage. If half-human tries to breed with non-human, the result is always 100% miscarriage. Basically, difference between mule and hinny.

Humans are true omnivores and can eat all sorts of food that is poisonous for other races. In fact, they can eat halfling food, orc food, elf food, goblin food etc. Goblins can eat orc food and halfling food but elf food is extremely poisonous to them. And so on. Which lead to us having edge and living in environments that others find extremely inhospitable. Basically, elves live somewhere, orcs live in some parts, halflings live in some parts but only humans live everywhere.

We are talking poisonous like theobromine is poisonous to dogs. It is found in cocoa and dark chocolate. Humans love chocolate! Dwarfs and goblins and halflings die from a single lick of it. Now imagine that weakness for something not as rare, like for example grain and flour and corn. Or maybe we are the only race that can drink and process animal milk into adulthood. The others get violently ill and/or die if they try.And milk and flour are used in basically all human recipes.

Also, relevant video (Vorta are immune to most forms of poisons from DS9)

Similarly, we can survive much greater range of temperatures than other races. Orcs, dwarves and elves overheat quicker, halflings and goblins freeze quicker than us. Making it worse, we developed materials which allows us to build housing in places other races find extremely inhospitable.

Basically, win hard enough against others and that gives you all the breeding edge you will ever need.

The reason humans didn't kill the others?

We still need somebody to clean the toilets, carry heavy stuff, work in the mines, clean the chimneys and make toys for our children.

Answer 3

Humans straddle the divide between r and k selected species.

Let us consider evolutionary theory.

http://www.bio.miami.edu/tom/courses/bil160/bil160goods/16_rKselection.html

The two evolutionary "strategies" are termed r-selection, for those species that produce many "cheap" offspring and live in unstable environments and K-selection for those species that produce few "expensive" offspring and live in stable environments.

Your long lived demihumans are well adapted to their stable environments. The goblinoids are short lived; perhaps the orcs are type 3 r-selected.

Humans straddle r and k: long lived with a relatively rapid reproductive rate, and environmental/dietary/ socio-cultural flexibility. Humans can take advantage of a broad range of environments stable and unstable which represent the broad middle of the bell curve. Demihumans are superior competitors only in the extreme environments at the far left and right of the bell curve.

Answer 4

Humans are more social, we collect in larger groups.

This may very well be the reason humans won out over neanderthal, who were larger, stronger, and tougher. Human had no physical advantages over neanderthal. But the average neanderthal tribe was around 10-30 individuals. while human bands range from 30-150. These are both controlled by how big a certain part of the brain is(likely the neocortex), basically how many other people we can keep track of. This is not a function of reproductive rate but just how social your species is. Orcs may breed faster but if they attack in groups of 10-20 they will basically always lose to a human hunter gatherer band of a hundred or more. They can pick off lone humans easily enough but as soon as it becomes large scale conflict they always lose.

Strength is all well and good be it can't make up for nearly an order of magnitude more enemies. Once humans start forming villages and cities the difference just becomes more exaggerated. Dwarves need highly structured laws to collect in groups of a hundred while humans can do it instinctively, and they still have a strong clannish streak. Elves just fail to collect in large groups, instead existing in small separate tribes. Every time they breed enough to exceed this number the tribe splits and one side moves. Halflings and goblins max out instinctively to groups of 30-60, so closest to humans, which is why they are still around, but they don't have the numbers to compete with humans directly. Expect most of these races to exist in marginal environments that cannot support tribes of hundreds of humans. Which is where we typically see them portrayed, dwarves in mountains, elves in jungle, orcs ins steppe, ect.

This difference does not have to be that extreme if human groups are about twice the size they will be hard to beat but not so hard humans can just steam roll over the rest of them, and wipe them out entirely.

Answer 5

Balance, versatility, and adaptability.

While humans have a large range of strengths and weaknesses, the other races are often humanoid, with one or multiple traits amplified. This comes with its own set of strengths and weaknesses on top of human ones. With humans being the in-between, we are the most balanced in any field, because we can adapt ourself in any situation. With some effort, we could adapt to the aggressiveness of Orcs, or the smartest of us could argue on par with intelligent elves. We could improve on Dwarven tech with technology they won't discover because they are holed up in the mountains too much.

As opposed to that, we can also adapt to any weakness of our enemy. We can outsmart Orcs, defeat Dwarves with our superior reach, and rally larger, more armored armies than the elves. This versatility means we can wriggle our way in anywhere, and eventually assert our dominance as a species.

Edit: I notice you didn't put intelligence differences in your question as traits of any race, and I went more for the tolkien like races. But theoretical this approach could work for any set of strengths and weaknesses.

Answer 6

Versatility is the first that comes to mind. It might be a different genre but in Star Trek Enterprise Admiral Forrest has this conversation with the Vulcan ambassador to Earth.

Where the Ambassador admits that they fear humans because of one simple thing, their versatility. And i think this applies to humans in most Sci-Fi and fantasy.

We are not the strongest but also not the weakest, not the fastest but also not the slowest. We aren't the most intelligent neither as we the dumbest. This makes our weaknesses harder to exploit compared to other races. Also we are better at adapting to situations, the orcs in your description would rely on their strength to solve their problems..once that's not a feasible option they would get stuck. While humans would just use one of their other attributes to overcome the obstacle.

And a other option that is sometimes used is breeding. If your humans reach adulthood faster or are able to produce more children in the same time span as the other races they would eventually just overrun the others.

Answer 7

Wanderlust

Why are humans found pretty much everywhere in the world? As we were developing as a species, humans were prone to walking pretty much everywhere. People would set out for the horizon and settle new lands, just because they were there. In this way humans had pretty much settled the whole globe before civilization was even a thing.

In your world, just as in ours, humans have great endurance, even compared to the other hominid races. Despite being outclassed in strength, dexterity, and senses, this means that the humans, more than any other race, will tend to get everywhere, while the other races tend to stick to their home countries.

This means that humans will likely be the vast majority in terms of numbers. A particular amount of land can only support a certain population, and the other races will have to have other means of coping with overpopulation. Perhaps orcs and goblins keep their numbers down with regular skirmishes, elves stop reproducing reproducing when their numbers are too high, dwarves do a little of both, and halflings...I don't know, start eating their own children or something when there isn't enough food (plenty of rodents do this). While humans just keep multiplying and when their population gets too high, they move elsewhere.

However, even though they are the majority across the world, humans will not (necessarily) kill off the other races, because each race is still basically a country, and humans would need to band together with other human countries in order to defeat them. As long as they aren't enough of a threat to make humans band together against them, they'll remain in relative equilibrium. This works better if those races also provide something valuable in trade, so humans like having them around.

Answer 8

Since you're creating the other races and give them the traits you want, you might want to consider, aside from the Jack of All Trades trope, another one which I've seen used from time to time: humans, from the point of view of other races, are unpredictable.

You might posit that, with individual exceptions, your other races might have defining behaviours, whether cultural or actually based on inherent psychology or biology, that tend to define their actions. To engage in blatant stereotypes, Orcs, for instance, might rely on leadership based purely on who is the physically strongest. Elves might have leadership defined by simple seniority. It could be confusing to them to come up against a race where that's not necessarily true, and whereas humans can get the idea of leadership going purely to the strong or the oldest because some humans also believe that, the orcs and the elves conceptually have difficulty dealing with a race where that isn't necessarily true.

So on a battlefield, the leader of the orcs might look for the strongest-looking human and go after them directly, utterly overlooking the physically average looking general who's actually directing the battle. In a diplomatic negotiation, the elves might constantly have to deal with the distraction that the person you're negotiating with isn't the oldest person at the table but might be the youngest.

They might adapt if the humans were consistent like every other self-respecting race, but they aren't. Sometimes the general on the battlefield is the best warrior, and sometimes the oldest person at the table is the one in charge. So the orcs and elves interact with humans not really getting, on a gut level, who is actually running things. The humans, on the other hand, because the other races they're dealing with are predictable in that sort of thing, are always prepared knowing what they're dealing with.

Answer 9

Because we are terrible at everything

I'm going to have a different take, and say that humans are so good because they are actually very terrible.

Why is that you say? Because by being terrible at everything, we need, by necessity, to find ways to overcome our shortcomings.

The dinosaurs were on this planet for 250 million years, yet in that time why did they not build cities? Why did they not build machines, cars, make guns, learn metallurgy? Humans did these things and they have effectively been around for only 400,000 years ago!

One theory is that the dinosaurs were too good at what they did, so they never had to learn to do what they couldn't. Humans in contrast:

• can't run that fast
• are very fussy at eating, and would die if we eat even the slightest wrong thing
• have babies that are completely defenceless and in fact would die if left alone for more than a few minutes
• have no hard shells for protection and in fact would die of infection if we even get the slightest scratch
• can't tolerate even the smallest temperature range

It is for this reason that humans need to overcome all these deficiencies and develop knowledge and technology to allow us to exist.

In comparison, all the other animals/types in your list do not have this, so they don't need better themselves, and remain the same as they have been.

And why don't we eliminate the others? Because we are also terrible at finishing a job, we are fickle-minded and lose interest. We don't want to spend the 80% to do the last 20%.

Answer 10

Unique human psychology.

Just pick any human vice or virture (perhaps one you want to make a point about), declare it an unique human behavior and you can construct a reason out of it why it helps humans to dominate the world.

Just a couple examples:

Humans are naturally dominant.

Humans are driven by lust for power. Other species simply don't have the ambition to rule the world. The Orcs might love a good battle, but they only fight for the sake of fighting. Governing an empire seems dull and boring to them. Halflings and elves are too nice to oppose their will on other species. Goblins and Dwarves don't think beyond their own interest or that of their community.

So humans rule the world because they are the only ones who really try.

Humans are naturally submissive.

Humans are the only species which is able to reliably follow orders, even if it's detrimental to the individual. That makes them the species most capable of large-scale warfare. No other species can get a couple thousand people to dress in uniforms, march in rank and file and die for their motherland. Orc armies self-destruct due to infighting, Elves have too much of a self-preservation instinct to rush into battle, Dwarves are too selfish to die for someone else, etc., etc..

Humans are benevolent.

Everyone likes humans because they are just so nice. Their laws are just and their deals are fair. When there is a conflict, humans seek to arbitrate with minimum bloodshed. That makes them the natural alliance builders of the world. Other species submit to human laws and order voluntarily, because it promises peace and prosperity.

Humans are malevolent.

Everyone fears humans because they are so evil. They are willing to do things other species' find repundant. Torture, slavery, genocide... nothing is too immoral for humans. Humans are capable of cruelties no other species would even think of, so nobody dares to oppose them.

Humans are flexible.

Humans are able to adapt quickly to situations. They are not bogged down by traditions or stereotypical behavior. This gives them an unique advantage at always finding the best solution to any problem they face.

Humans are stubborn.

Humans are very stuck up in their traditions and their way of doing things. But this leads to a lot of society cohesion. While other species debate endlessly how a problem should be tackled, humans have the tennacity to just do things the way they always do. And thanks to never faltering when attempting things, they often succeed eventually through sheer force of will.

...I could go on and on. Pretty much any personality trait can be exaggerated in humans by declaring it extraordinarly rare in all other species' and then cosntructing a reason why that particular trait is an advantage for humanity.

Answer 11

Humans focus on grasslands and planes, due to our endurance and height advantage. These types biomes tend toward large, contiguous areas. This leads to large, contiguous empires. Your elves probably rule the forests (one elf-king per forest), your dwarfs probably rule the mountains (one dwarf-king per mountain). One human nation or alliance might rule all of the interstitial areas, giving them superior ability to focus power, as well as an advantage in trade.

Another advantage of ruling the grasslands is this gives superior farming ability. Humans may or may not breed faster than the fantasy types (as others have pointed out, the idea of a universe full of species that mostly breed slower than humans stretches suspension of disbelief, considering we're among the slowest breeding species on the planet). However, we should be able to sustain the highest population reliably -- try farming on a mountain. Forests, maybe, depends on how much the elves want to impose on nature.

In terms of technology, there's always the interesting trivia tidbit that I've seen around here, that bronze is generally competitive with iron in most cases. However, as an alloy of tin and copper, which may not pop up in the right place, it requires a larger nation. This maps perfectly to the fantasy tropes -- humans can mass produce lower quality cast bronze swords, while the dwarf craftsmen forge iron more slowly, but in their secluded mountain holds, and on occasion accidentally inventing steel.

Militarily, humans will get by with their large population and superior marching endurance. A unit of men may not be particularly ferocious compared to any one unit of Orks, but the humans have the advantage of deploying two units in the front, and hey, here comes the unit in the rear that spent all night marching from the next city over.

Answer 12

You don't specify lifespans - but I'm going to assume that lifespans are like those commonly portrayed for fantasy creatures. Thus, Orcs and Goblins are (likely) shorter-lived than Humans, Halflings are more or less the same, and Elves and Dwarves are longer-lived.

Why are Humans more successful than Goblins and Orcs?

Goblins and Orcs do not individually live very long. Like less-advanced animals, they likely mature more quickly than Humans. Over the briefer time that they are maturing, they don't have a lot of leisure to pursue education and intellectual advancement. Their technology and military tactics alike remain fairly primitive, because of this relative immaturity. This may be made worse by the current warlike state of Orcs and Goblins, because already limited life-expectancy is cut down further by the high chance in falling in battle, either with other races or due to internal strife. But that very incidence of early death only effectively shortens the window of progress even more, leading to a continuation of primitive, warlike inclination.

In fine, the critical mass of civilization that Goblins and Orcs are capable of achieving with such short lifespans is very low. Remember, each generation must train the following generations in their wisdom, but if the wisdom of someone decade-long (or more) veteran in their mid twenties is the best wisdom which can be passed on, that doesn't augur well for the future progress of their kind.

But although Orcs and Goblins are fairly primitive, Humans are not going to easily wipe them out. At least, not quickly. Those other kinds breed quickly, grow up fast, and fight viciously. The Orcs and Goblins gradually lose territory to the advancing Humans - though they sometimes push back and reclaim some of the ground they've lost. It is an equilibrium which is not permanent, but which largely holds right now.

Why are Humans more successful than Dwarves and Elves?

Okay, so if Humans are better than Goblins and Orcs because they live longer, then Dwarves and Elves should be even better and more successful, right? Yes and no.

The longer-lived races have all the time in the world to pursue advancement. Dwarves can easily live a few hundred years, and Elves live even longer spans. Craftsmanship can be perfected. Complex disciplines can be plumbed to their deepest depths. Elves and Dwarves tend to reach great heights individually, and to pass their achievements along to their children - what few children they have. As Willk discusses, long-lived creatures rarely produce many children, even over their longer lifespans. Aside from this, there is little urgency to progress. Yes, an 800-year-old Elf will have achieved much in her life - but possibly much less than 8 times what an 80-year-old human woman has. What's the rush? There's all the time in the world!

There are several implications. Elves and Dwarves may be less inclined to engage in division of labor than Humans (hence giving up the efficiency of breaking up work into smaller tasks and specializing). If their population growth is slower, there will be fewer dense population centers, and dense population centers are actually required (at least in Human experience) for real advancement; lots of people having lots of ideas, which compete and have the best rise to the top, over and over...

There's a sweet spot for not individuals but races to advance - and our Elves and Dwarves have overshot that point to differing degrees. Now, if there is relative peace between Elves, Dwarves, and Humans, then things are going to be a bit more complicated than just having Humans spring forward and leave Elves and Dwarves behind - because some of the longer-lived races can effectively become the experts of Human advancement which individual Humans could never live long enough to manage. And Humans would thus highly value long-lived Dwarven craftsmen and longer-lived Elf sages integrated into Human institutions. (Which partly explains why Humans don't just wipe these races out.)

Then what about Halflings?

Everything we've discussed about lifespans in regards to Humans versus the other races applies equally well to Halflings. So why aren't they exactly as successful, the perfect foil to the spreading Human communities?

Halflings are just smaller. Even if they are stronger than Humans (relative to their size), Humans still have size and leverage. Maybe, alone in the forest or in a tall-grass meadow, a sharp-eyed Halfling can spot a lumbering Human and easily hide, easily fling a well-aimed stone. But with those short arms, that stone may not be going fast enough to take down that tall Man. And in open battle, Humans have built-in high ground.

Perhaps serious battles between Halflings and Men have never happened - because Halflings are smart enough to have worked out in advance how they would play out. So Halflings make nice with Humans. What other choice have they got? And Humans are likely to tolerate Halflings, up to a point, because they look so much like Human children. At least until the Humans' actual children need a little more room to live...