I was inspired by my other work with explaining realistic weapon choices for fantasy characters and I decided that I should apply my pursuit of realism in fantasy in a way that I actually know about and would be able to extrapolate, rather than summarize and parrot. So without further ado, here is what we can know about the anatomy and sociology of fantasy races, just by looking at them. Important Term: An important term that will be coming up often in this is sexual dimorphism, this term will be coming up often. Sexual dimorphism is how males and females differ from each other physically. This tells a surprising amount about a species. Orcs: Most versions of the stereotypical orc seem to live in a social hierarchy like the gorilla, where might rules breeding. Men are big and strong and women are much smaller than them even if the women are stronger than human men. This is very similar to the gorilla, and this can be seen to be caused by their harem society, where the biggest and strongest men are able to breed with the women in the group, and limit other men from doing the same. The bad news is this means that also like the gorilla, orc genitals would probably be small compared to their body size. Other bad news is this would also induce a social structure where the females aren't equal to the males, so the women would in fact stay home during war. So no independant orc women unless they are at least almost as big and ugly as the men. Elves: Funnily enough, Tolkien had it right when he said that elves mated for life, I don't know if this was due to him having some knowledge of evolutionary biology (doubtful) or if he just wanted to make elves more pure (More likely). Either way, we know they would mate for life because it is hard to tell the males from the females due to the males seeming like effeminate humans as well as the females. Ironically, such perfect lack of dimorphism, and longevity would also cause small genitals (at least compared to humans), the size of human genitalia is attributed to highly competitive mating caused by our social monogamy (while our sexual dimorphism is caused by infidelity). Elves not only would not need to be highly competitive due to the lack of dimorphism, but would also not need to be highly competitive because they could simply wait (as creepy as that sounds) for a suitable mate as their mating time is not limited. Dwarves: It would be hard to say anything about Dwarves that wouldn't also be true of elves as listed above, as there is typically little sexual dimorphism. Their lack of dimorphism trends to attributes typically seen as masculine, but that still means monogamy for life. However, their lack of longevity would mean more competitiveness, and their more masculine appearance would imply a society built on more masculine ideals like strength and combat ability. It just would apply to both women and men instead of just men. Dwarf women warriors would be almost as common as men, but would be less common not because they are less capable but because they occassionally are carrying a small dwarf inside of them and have to raise them, however since in fiction they typically live longer than humans, this wouldn't be a permanent thing, and so after the children are raised, they can return to battle. Centaur: First, a notion to dispel. A joke was made that since human babies can barely hold themselves up and since foals could run since birth, a baby centaur would have an infant upper body, which would flop about while the horse lower body would be able to run around. Since it is undebatable that the horse's reproductive organs would be used, it is time to enlighten some people. Babies are like what they are because our birth canals didn't grow significantly with our head size, meaning that babies have to start smaller and give more room for growth. Since a horse body has a birth canal large enough to give birth to a foal that can run from birth, we can use logic to dictate how big the human baby part would be upon birth much in the same way that I have noted that a human body makes sense in place of a horse head (horse heads are actually about the same mass as the upper body of a human). Ergo, we can look at a foal and see what point in human development a human upper body is comparable to a horse head. Thus we would reasonably conclude that a just born centaur would have a large toddler or young child human body stapled onto their horse half, and thus would be able to hold itself up just about as well as a foal could. Their beginning large size would cause a shorter developmental cycle, and thus a shorter lifespan than humans. They would however have a longer lifespan than horses. They would spook less easily than a horse, but not a lot could be said of their resulting social structure. It would be likely that they would have a similar social structure of horses with some aspects of human social structure added in, but since it is essentially two animals that are very different in manner stapled together, not much could be said for how they would act other than "Both like humans and horses." So go wild with your interpretation of what that would mean for them.