Creature Culture (part 1)

One of the standard elements of Fantasy (and SciFi) writing is the presence of fantastic creatures.  The presence of these beings in the story can serve many purposes.  Often they are used as foils, to show the positives and negatives of the human societies we build.  Some times they are simple adversaries, acting as obstacles for our heroes to overcome (and/or slaughter without too much guilt).  The uses of these creatures are legion, but not all creatures are "created" equally.  When populating our worlds with fantastical creatures, it behooves writers to put just as much thought into the "others" as they do into their humans.  Readers care if your creations make sense.

Humans are generally the "youngest" culture in a fantasy world.  This is often used by the author to instantaneously create a "lived in" feel.  These older, and possibly wiser, beings have histories that go back untold generations.  Potentially then there are many things that humans can learn from these folk.  One question the author needs to answer though, is "Why have these ancient cultures not progressed beyond their current level of technology?"  or to put it more plainly, "Why haven't your creative and industrious dwarfs moved beyond smacking people with axes and hammers?"  Maybe more importantly, if these intelligent creatures have been watching humanity develop, have they been keeping us in check or exploiting us in some way?  Larry Niven's Ringworld explores this a bit. 
    In many of the books I read while growing up, as well as the RPGs, there were characters that were half-this and half-that.  I suspect it's one of the reasons these different creatures are commonly referred to as "races" and not "species."  It is a good way to investigate the real world human issue of mixed parentage without being too blatant.  One interesting repercussion is that, (by definition) in order to produce viable offspring (which means that the child can subsequently reproduce), two beings must be of the same species.  Consequently, in a setting that uses half-whatevers (produced through natural means), the creatures involved can not have significant genetic difference and their cultures have gone through development of similar duration.
    When creating a species different from humans, basic physical differences can (and probably should) lead to significant societal impacts.  Nature has shown us many different examples of reproduction with varying benefits and hindrances inherent.  For example, animals that lay eggs are not slowed by carrying developing young, but the eggs are more susceptible to predation.  Diet (carnivore, herbivore, omnivore, other?) is a determining factor in where/how we live as well as the success of various body designs.  Pure carnivores would have difficulty forming close knit societies since their food source requires a much larger area (can you imagine them developing farming to keep their food animals close together?). 
    Above all, the place held by the fantastic creatures of your world needs to be just as reasonable as their human counterparts.  If you want your dwarfs to live entirely underground, you probably should know what they eat.  Do they have farms topside?  Are there hidden pastures up in the high places?  Maybe there are subterranean creatures that they raise in underground caverns (plants won't grow there silly, but other things may).  What do things that live underground look like?  Anyway, where did all those underground caverns come from and why the hell would the dwarfs choose to live there?  Similarly, if your elves don't have mines or forges, where did they get their steel?
    It is important to remember that we are creating essentially alien cultures.  The basic motive force behind most organisms is simply to perpetuate the species.  Strategies alternate to our own for doing such, like ant colonies, may seem utterly incomprehensible.  You can find a good example of a culture that feels truly alien in Tad Williams' series (Memory, Sorrow and Thorn).  Having lived in other countries, I can say that even other human cultures can be downright mystifying.  There is no such thing as a universal language or experience.  What is important to one culture may be considered stupid or even anathema in another. 
    Knowing all of these things about your creations is important because it shows you where you can create conflict.  If your pixies lay eggs, they may need to defend those eggs.  When those stupid humans knock down your tiger-men's barbed wire fence, they're going to hear about it.  Maybe your dwarfs are willing to kill for beer, since they've never grown wheat, barley or hops.  Knowing how and where these cultures intersect is key to figuring out how to make things go wrong.  After all, in a fantasy world, it's all the writer's fault.