Where do human rights come from?

The phrase "human rights" is so ubiquitous as to have become something many of us take for granted. We often forget that, for a very long time, there was no such concept, at least not in the way we formulate these rights today. So the question is, where does the concept come from. Three human rights practitioners tell us where the idea of a "human right" came from, and what makes a right universal.