Human beings are social animals which have for most of our history (up until about 12000 years) evolved in tribes in no more than 150 people. The rapid proliferation of our species was among other things enabled by language through which we were able to create stories. Religion, nation-state, and money are all examples of stories that enabled us to create larger societies which eventually conquered smaller, tribe-like communities of people that didn't evolve sufficiently over time. Besides that, female humans are choosy mates (as opposed to most other primates) by which given an unrestricted choice, a small percentage of males receive attraction of the majority of women (Pareto distribution). The inverse is not the case, the distribution of female sexual market value is normally distributed. This phenomenon is studied in research on ancestor's genes and is also manifested in the online dating market. So essentially, this is the nature's way to filter out quality which enabled us to accelerate the mastery of our environment.
While living in tribes, self-governance was possible as a way to establish strong reputational networks among people that knew each other. This way people policed themselves, without any need for a central entity. As humans gathered in larger and larger groups through story-telling, we were able to collaborate with people that we didn't necessarily know. Christians fighting side by side on the Crusades didn't need to know each other, they just needed to believe in the same story, the story of the Bible.