On a related note, I have recently been wondering if the large scale swings in society from being outgoing to being insular and back, might be evolutionarily beneficial due to the speed of genetic drift varying for different sizes of breeding populations.

Small populations get the fast drift for adaptation, but mixing those with other adaptations from other small populations gets strength in depth, so you have two opposing evolutionary strategies, one which prefers isolation of groups and one that prefers mixing.

Over evolutionary timescales, oscillating between these two behaviours could presumably get baked into the genes, so leading our politics to swing between isolation and gregariousness as part of a natural evolutionary cycle.