Continuing on the theme that the novels of Jane Austen can be used to explain just about anything, I give you this passage from Dorothy L. Cheney and Robert M. Seyfarth’s Baboon Metaphysics:

In sum, monkey society is governed by the same two general rules that governed the behavior of women in so many 19th-century novels: stay loyal to your relatives (though perhaps at a distance, if they are a social impediment) but also try to ingratiate yourself with the members of high-ranking families. The two rules interact in interesting ways. For members of high-ranking matrilines, the rules of kin-based and rank-based attraction reinforce one another, whereas for the members of low-ranking families they counteract. A member of a high-ranking matriline is attracted to her kin not only because they are members of the same family but also because they are high-ranking. A member of a low-ranking family may be attracted to her kin, but she is also drawn away from them by her attraction to unrelated, higher-status individuals. As a result, high-ranking families are often more cohesive than lower-ranking ones. Or, to paraphrase Tolstoy’s Anna Karenina, all high-ranking families are alike in their cohesiveness, each low-ranking family is cohesive or not, in its own way.