Thanks. That seems a fascinating topic, the emergence and evolution of these "protected classes" over time. I'll try to descend into your links once I have mor

Thanks. That seems a fascinating topic, the emergence and evolution of these "protected classes" over time. I'll try to descend into your links once I have more time, but a TL;DR discussion on "why we drew the line here, not there" would be great too. Is it mainly a function of how vocal or powerful a subpopulation is? Something else? What other subdivisions will become privileged next? Where is this trend headed?