The question [Centaurs, do they have control of their bodily functions?][1] asks what I consider to be a legitimate question (albeit containing misconceptions about real-world zoology) about a fictional species that appears in RPGs. It was put on-hold as being primarily opinion-based, however I'm arguing that - barring the necessity for any magical hand-waving or simply because the species in question is simply *too* alien - it is possible to provide answers to such questions that are based on scientific fact. I based my answer to this question on the point that - unless the specific RPG in question specifically states something to the contrary - players should be expected to extrapolate assumptions about fictional species from similar real-world species. Looking at http://www.dandwiki.com/wiki/SRD:Centaur and http://www.dandwiki.com/wiki/SRD:Centaurs_(Race), I can see all sorts of mechanical rules, but the description of the species is literally one line: > A centaur is as big as a heavy horse, but much taller and slightly heavier. A centaur is about 7 feet tall and weighs about 2,100 pounds. From this, I can only assume that the D&D 3.5 rules assume that everyone just *knows* what a centaur *is* - or can look at the picture in the hardcopy book. Knowing the mythology of centaurs, and reading the rules of the game in question, I can make the assumption that: *A Centaur is a fusion of the body of a horse below the neck, and the torso of a humanoid from the waist up.* I don't think anyone would really argue with that all that much - except for the exact definition of "waist" and "neck". From that we can extrapolate certain assumptions: since a centaur body-plan is a chimera of human and horse parts, *unless the game's rules state otherwise*, we can assume that (since both species involved in the chimera are mammalian) a centaur is mammalian, that due to the dentition that can physically fit into a humanoid mouth it must by necessity eat something more nourishing than grass, and so on. In the case of other mythological creatures such as the Pegasus, simple physics dictate that barring a much higher atmospheric density and a much lower gravity, such a creature could not fly. However, the rules of the game state specifically that they *can* fly, and *do not* state that different atmospheric and gravitic conditions exist - in fact rather to the contrary if you read between the lines - so from that we can conclude that since pure physics and physiology are insufficient to explain the phenomenon of flying pegasi, magic *must* be at work. In the examples above, a centaur can be made to work by simple physiology, and a Pegasus can be made to work by stating that "Magic is required to make it fly". The second point that I must address is the relevancy of such questions to RPG SE. Would they fit on Mythology SE or Worldbuilding SE if they ever go beyond the commitment phase? Perhaps, but at the time I write this question, *they have not*. Would they fit on SciFi SE? Perhaps. I would suggest that RPG SE is the *best* place for such questions as it is really only role players and world builders who might ask such questions and find the answers relevant, and at present RPG SE is the only active SE site that deals with world building. **Question:** Are questions about species appearing in roleplaying games that require research outside the rules in the specified RPG system on-topic? EDIT: To address Brian Ballsum-Stanton's comment regarding the meta question [Are campaign research questions on topic?][2], I believe that this sort of question *is* campaign research, as long as the system is specified, or other constraints specified. In the example question "Centaurs, do they have control of their bodily functions?", the system *is* specified (D&D 3.5), and the aforementioned rules *do* provide some (albeit very scanty) information. Certainly, the subject of the question may seem trivial and silly from the point of view of an outsider, but to the players, it may be an issue of great importance that could change the course of a whole campaign. Who are we to judge? A question about real-world campaign research indeed may *not* be relevant here, though the consensus appears to suggest that it *is*. And as this type of question is about fantasy species appearing in a specific RPGs, even if those rules don't say everything the players want to know, the rules provide a starting point that a person with other expertise can expand upon. Where but RPG SE is a role-player likely to find a person familiar enough with both the RPG in question *and* the other area of expertise? [1]: http://rpg.stackexchange.com/q/39545/8962 [2]: http://meta.rpg.stackexchange.com/questions/570/are-campaign-research-questions-on-topic