Democracy may be a biologically advantageous political system. When I'm referring to democracy I am referring specifically to the American model which is a limited government, multistate, Republic.
The biological fact of human beings, Homo sapiens, is that we are like apples. Every child born is a reversion to the standard human being. Plant a fancy Fuji apple seed and you get the standard crab apple. We constantly return to the norm of the population. With excessive inbreeding, our lineage dies.
If that is the biological fact, then any idea of a biologically bred upper-class, or lower-class, is bound to fail because there is no biological way to maintain the inbreeding superiority or inferiority in humans. Certainly, in the past, such inherited class categories have been created by culture. When families tried to inbreed they died out.
In the most extreme cultural case, Japan, the hierarchical social structure is maintained by selection of outstanding genetic individuals and marrying them higher in the hierarchy for their talent. This is still a cultural mechanism since the genetic material (their children) always revert to the population norm.
I would suggest that American-style democracy creates the most favorable environment for the favorable-sporadic-random gene to become highly productive for the society. That productivity may be in any domain: culture, science, politics or most importantly commerce. Such wonderful outliers have the greatest chance of making a social contribution in an American world.
Doesn't this strike you as an interesting thesis? That American-style democracy has a biologically favorable role.
A friend commented that American style uses a high level of chaos to produce innovation. Yes, and that is also how biology works in the genetic world. Random variation with selection for favorable attributes.