Interesting thoughts, Ironside. I would just point out that women and slaves were eventually awarded full rights, and even children have some protection in most societies. The trend seems to be one-way. Here in the U.S.A., there's a large and mostly unexamined trend where childless couples treat their pets as surrogate family. It's a seismic shift in the human/pet relationship. (And of course some people have done this in the past; what's amazing is the scale of the phenom these days. It seems as though most pet owners now consider Fluffy and Scraps to be full family members.)

Anyway, what I take away from this is that we, as humans, are built to be sentimental whether it makes any sense or not. We'll bond with anything. We're emotional sluts. It's an aspect of our character that I've never seen explored in SF, which is the place you'd expect to see such themes played out.