This may just be arguing semantics to you but to me there is a very significant difference between the words species and race and the two aren't interchangeable. Species: Two lifeforms (animals, plants, etc.) that are genetically different to the point where they cannot interbreed viable offspring. Though plants have been known to make viable hybrids, animals by definition cannot. Animals that are closely related may be able to produce an offspring (mule, hinny, liger) but they cannot reproduce to create another of their kind. A mule cannot mate with another mule and produce a mule. Race: The human equivalent of animal's breed or plant's cultivar. Meaning they are of the same species and can produce viable offspring. A European may look different from an African, but they are both still human. My fantasy novel has a few sentient species and races that divide those species. I am not going to go out of my way to define the two in the narrative and explain the differences as it would be terrible writing, but I want to know if it would stump my readers at all at a casual reference, should it arise? Would it be at all a problem?
As a general tendency, yes, but as an absolute rule, no. Felids (the cat family) are known for their capacity to produce viable fertile offspring from inter-species matings. And some completely genetically crossable species are considered separate species because the differences in their behavior preclude mating, not because the recipe doesn't work. The dolphin clan in particular is known for this. But that's not your question. I doubt this would confuse your reader at all. It may also be a valuable tool to show, from the perspective of your characters, how it is that they define differences and where they draw the lines. If you've not read Larry Niven's Ringworld (and the subsequent novels in that series) I would suggest them to you as field research on the concept. Mr. Niven deals extensively with the idea in these novels.
Historically, there was not much distinction. Races among humans in the past were treated as different species. A disturbingly large segment of the Western world's people actually believed during WWII that Japanese possessed tails. The fact that most of the world's people accept that all races among humans are the same species is a sign of progress, and is a newer idea than most people suspect.
our species is commonly referred to as 'the human race'... while that's not semantically or zoologically accurate, it is a term that's in general use, so we can get away with using it... as far as what you call the various types of critters in your novel, as long as it will make sense to the reader, i'd say write what you will...
If you have a character who has lived among the alien species, then they can be an excellent way to show the reader how these differences are treated semantically. You might even make up words to use to illustrate different points. A top-of-my head example: You might have five different words or suffixes used to designate race / species relationships. Dossal for a subgroup -- a group with roots in a parent group, but which has been separated by geography or custom. Drest for incompatible dossal, ones who can no longer produce viable offspring. Thedo for dossal who have gone beyond incompatibility to the point where their thought processes are no longer mutually understandable. Add the terms edso, same-thought-people, and odret, same-legend-people, and you have a bunch of terms that can come in ridiculously handy. Christians are odret, as are all Muslims, as are all Vikings. Solders with strong esprit de corps are odret and possibly edso. Dogs and wolves are borderline thedo, as are gorillas and chimpanzees, but thedo can also describe a religious extremist and an ardent atheist -- worldviews so different they can literally not understand one another even if they speak the same langauge. Human races might be considered dossal, and humans and Neanderthals might be drest. Teachers unions are edso, as are many political parties. Use these terms often enough, and your audience will undertand. Especially since not all of them involve genetics. An alien and a human who were invested in the same cause might well become edso over time, and two humans could be thedo even if they grew up in the same town. Then add a measure of worldbuilding and stir. You could have conflict based on the race / species / subspecies paradigm when it meets the edso / thedo / dossal / etc. paradigm. You could have a character trying to convince another that a third is a friend or ally -- that they are edso, even if they are different species. You could have stable alien societies where there are many, many different races and species but they all subscribe to the same creed -- even if it's one as basic as "I agree not to kill anyone else who is a Member of the Creed." Just throwing out ideas. I guess what I'm saying is, don't leave your readers in the dark because you're worried that a paragraph of exposition is too much. It shouldn't be, if you've developed your world sufficiently.
Species: Two life forms (animals, plants, etc.) that are genetically different to the point where they cannot interbreed viable offspring. Not exactly. It’s not that members of different species cant breed due only to the inability of their DNA to combine: the point is, they have a gene flow barrier between them. Usually the barrier is purely genetic, but may be for other reasons. Genitalia maybe mismatched, preventing mating. Behaviour can come into it– coming into season/heat at different times of year, or a different sounding mating call - these things can seperate species, even though they maybe genetically compatible. (Of course you may argue having different genitals is due to DNA (true), so the above example shows genetically incompatible, but here we are interested weather the egg and sperm can or cannot combine, to produce viable offspring, once brought together.) Biology is messy and absolutes classifications don’t work so well, no matter the human urge to attach neat labels. Linnaeus did a great job organizing nature into boxes, and laid the groundwork for Darwin and others, however his classification of species cannot be considered the final say in the matter – after all species are not fixed, but instead in a constant state of change. How ‘human’ are you? Your cells are powered by mitochondrial DNA, which started out as a bacterial parasite within a cell (most people are not aware of this second package of DNA that is exists separate to our nuclear DNA, but which we could not live without) – and your nuclear DNA has a great deal of viral sequences in it – retroviruses (such as HIV) have the ability to cut and past themselves into our DNA (evolution doesn’t only work by Darwin’s original notions of natural selection!) There is genetic variation in human populations across geographic regions, however it is no more logical to say all black people are the one race as it is to say all people over six feet are the one race. Race definition is mostly the imposing of social markers into DNA differences. Race is tricky (impossible!) to define scientifically - though human gentic difference should not be denied. Of course there are may species of cats but only one species of human, and yet different human races have diffrent abilites ( not popular to say, but true if using the term 'race' as meaning genetic differces distinguishing human geographical populations). Would it be at all a problem? I think it would be a problem if you tired to invent biological categories without explaining those categories. It wouldn't take much explanation, but some would be needed to make the idea believable.
The species/race distinction always bugged me a bit in fantasy fiction. Elves, dwarves, mermaids... they are different species, not races, but they are called races.
Because, as has been mentioned, terms like species and race are constructs. Artifacts of language and human perception, and more often than not, the definitions which are intended to create absolutes are anything but absolute.* So, what happens? We create these terms to categorize and then imbue these terms with emotional cargo. Emotions do not answer to reason. Not at all. So in Fantasy stories we see the term race instead of species. Why? Because the different fantasy peoples all have one thing in common. They can communicate with each other. They can reason with each other at some level. They are all human in that word's definition of a reasoning rational, self aware being, not it's other meaning as a replacement term for the coldly taxonomic homo sapiens sapiens. If they get called species in Fantasy stories, now we have a bunch of negative emotional baggage that the author does not wish to include. *To give you an example of how human perception can come into play when it comes to how we categorize things, let me give you an example from my native Spanish: In Spanish, a butterfly that is active during the day is called mariposa. If a moth is also active during the day, it is also called mariposa. Moths that are active at night are called mariposa nocturna. See how the moth clan has been divided now into two categories, lumping one part along with butterflies (which they are not)? To further confuse the issue, if the moth (day or night) creates a grub that is destructive to human valuables, then it is not called mariposa or mariposa nocturna, but instead it is called polilla. Many other critters that are destructive to human valuables are also called polilla which are not related to moths or butterflies at all. Still with me? I would not blame you if you were not. The methodology of Spanish says that the physical/biological differences between daytime butterflies and moths are not important enough to warrant different names. The methodology also includes the idea that if something is active during the day or the night, that is a feature important enough to warrant a different name, and that if the critter is somehow destructive, then they all go into one bucket regardless of how many legs, wings or antennae they might have. Spanish (and the other Romance languages) also have different names for body parts depending in whether the body part belongs to a human or a non human. In Spanish a human leg is a pierna, but a dog's leg is a pata. Were you to refer to a person's leg as a pata, this would be offensive in the extreme. In English we make no such distinction. A leg is a leg is a leg. It seems silly to the English speaker to have different terms, but for someone coming from a Romance culture it seems insensitive not to have a separate set of words for humans vs other animals. All perception. Nothing but. See?
