Self-sustenance requires that humankind not only use social tools such as language and thought to gain social power over others, but also to achieve cognitive consistency with the actual impacts of actions and the patterns sensed in the real world. In other words, stage 4 is when science and rationality begin to take precedence. Stage 5 is the realization that humanity as an entity has global behaviors and impacts. Eric Schwarz is author of this position in the paper cited below.