Great concise article. It's interesting how small humanity's core and even extended groups are. Modern civilization and population density is very recent in ev

Great concise article. It's interesting how small humanity's core and even extended groups are. Modern civilization and population density is very recent in evolutionary terms, and our brain's just can't make good use of that much humanity. But even the casual circle is interesting, I think of everybody on LinkedIn as a kind of casual circle. Business casual, where we're all advertising our business acumen to each other. Both as desirable employees, and as desirable people to work for. Do large twitter circles advertise casual habits? To what end?