@jd In this vein, there is an excellent short story by Octavia E. Butler called "A Necessary Being" that is, I think, an attempt to imagine a sapient species that is inherently, genetically hierarchical. The more blue color a person has in their skin the higher their rank is because the level of blue corresponds directly to how strong, fast, and intelligent you are.

It's a fascinating story and Butler is a stunningly good author. I highly recommend everything she's written. Brace yourself though shit tends to get real real quick.