Things you learn while grading exams

From a delightfully digression-packed essay on John Mackie's argument from relativity:

Anyway, back to monogamy, at some point humans become monogamous. It may have been brought about by natural selection processes that favour our species (a human is likelier to shoot you for sleeping with someone else, perhaps? than an animal would kill its mate → not just because animals have no firearms & excluding the likes of black widows that devour their male companion for nutrition after creation. More sensibly, the formulation of settlements and organized living would decrease the pool of mates met.)