A passage from Keeping Together in Time: Dance and Drill in Human History by Harvard historian William H. McNeill:

McNeill is a big reason why your mandatory undergraduate history classes all stress the contact of cultures — both good and bad — as the energy source that drives history. In this book, he posits that communal dance and song conferred ancient evolutionary advantages on humans. We are social creatures, so we like moving in social harmony. We gain the strength of confidence in our place within the social unit that moves together. You can see this phenomenon in the tight-knit communities that form around dance, but also in the US Army basic training company.

By his own admission in the opening chapter, McNeill wrote Keeping Together in Time without any scientific journal entries or psychology papers to underlie his argument. He was responsive to his memories of basic training. Perhaps the truth of his thesis is so obvious that no one had, or has, examined it. Moving together in time is as universally human as war. “Mass movement” is a literal term as well as a political term. If history is made of human beings, as the French say, then it is made up of human beings in motion.