I don't really like the use of the word "evolved" in this context. It implies that being poly is a superior way to be. That it's for people who are "more developed".
It's not superior and being monogamous isn't inferior. They're just different relationship styles that work better or worse for different people. It takes a hell of a lot of personal skills to have a successful poly relationship and it takes a hell of a lot of personal skills to have a successful monogamous relationship.